LTC3883/LTC3883-1 Single Phase Step-Down DC/DC Controller with Digital Power System Management Description Features PMBus/I2C Compliant Serial Interface – Telemetry Read-Back Includes VIN, IIN, VOUT, IOUT, Temperature and Faults – Programmable Voltage, Current Limit, Digital Soft-Start/Stop, Sequencing, Margining, OV/UV/OC and Frequency Synchronization (250kHz to 1MHz) n ±0.
LTC3883/LTC3883-1 Table of Contents Features...................................................... 1 Applications................................................. 1 Typical Application......................................... 1 Description.................................................. 1 Table of Contents........................................... 2 Absolute Maximum Ratings............................... 4 Pin Configuration........................................... 4 Order Information...................
LTC3883/LTC3883-1 Table of Contents Topside MOSFET Driver Supply (CB, DB).................45 Undervoltage Lockout..............................................45 CIN and COUT Selection............................................45 Fault Conditions.......................................................46 Open-Drain Pins...................................................... 47 Phase-Locked Loop and Frequency Synchronization.......................................................
LTC3883/LTC3883-1 Absolute Maximum Ratings (Note 1) VIN, SW....................................................... –0.3V to 28V Topside Driver Voltage (BOOST)................. –0.3V to 34V Switch Transient Voltage (SW)...................... –5V to 28V EXTVCC, INTVCC, BG, (BOOST – SW) .......... –0.3V to 6V VSENSE+, ISENSE+........................................... –0.3V to 6V RUN, SDA, SCL, ALERT.............................. –0.3V to 5.5V FREQ_CFG, VOUT_CFG, V TRIM_CFG, ASEL, VDD25........................
LTC3883/LTC3883-1 Electrical Characteristics The l denotes the specifications which apply over the specified operating junction temperature range, otherwise specifications are at TA = 25°C (Note 2). VIN = 12V, VRUN = 3.3V, fSYNC = 500kHz (externally driven) unless otherwise specified. SYMBOL PARAMETER Input Voltage VIN Input Voltage Range IQ Input Voltage Supply Current Normal Operation VUVLO CONDITIONS Undervoltage Lockout Threshold when VIN > 4.
LTC3883/LTC3883-1 Electrical Characteristics The l denotes the specifications which apply over the specified operating junction temperature range, otherwise specifications are at TA = 25°C (Note 2). VIN = 12V, VRUN = 3.3V, fSYNC = 500kHz (externally driven) unless otherwise specified. SYMBOL VINRANGE VINSTP VINTHACC tPROPVIN PARAMETER Full-Scale Voltage Step Size Threshold Accuracy 8.
LTC3883/LTC3883-1 Electrical Characteristics The l denotes the specifications which apply over the specified operating junction temperature range, otherwise specifications are at TA = 25°C (Note 2). VIN = 12V, VRUN = 3.3V, fSYNC = 500kHz (externally driven) unless otherwise specified.
LTC3883/LTC3883-1 Electrical Characteristics The l denotes the specifications which apply over the specified operating junction temperature range, otherwise specifications are at TA = 25°C (Note 2). VIN = 12V, VRUN = 3.3V, fSYNC = 500kHz (externally driven) unless otherwise specified.
LTC3883/LTC3883-1 Electrical Characteristics less than the minimum endurance specification. The RESTORE_USER_ALL command (NVM read) is valid over the entire operating temperature range. Note 14: The LTC3883-1 quiescent current (IQ) equals the IQ of VIN plus the IQ of EXTVCC. Note 15: The LTC3883 includes overtemperature protection that is intended to protect the device during momentary overload conditions. Junction temperature will exceed 125°C when overtemperature protection is active.
LTC3883/LTC3883-1 Typical Performance Characteristics VOUT 1V/DIV tFALL = 5ms tDELAY = 10ms 5ms/DIV 3883 G10 CURRENT LIMIT (A) WITH 1mΩ SENSE RESISTOR RUN 2V/DIV 60 50 40 30 20 10 0 –10 –20 VSENSE 50mV VSENSE 25mV 0 0.5 1 1.5 VITH (V) 2 MAXIMUM CURRENT SENSE THRESHOLD (mV) Current Sense Threshold vs ITH Voltage (Low Range) Soft-Off Ramp 2.
LTC3883/LTC3883-1 Typical Performance Characteristics VOUT Command DNL INTVCC Line Regulation 0.3 5.25 1.5 0.2 5.00 1.0 0.1 0.5 0 0 –0.1 –0.5 –0.2 –1.0 0.5 1 1.5 2 2.5 3 3.5 VOUT (V) 4 4.5 5 –0.3 5.5 4.75 INTVCC (V) DNL (LSBs) INL (LSBs) VOUT Command INL 2.0 3.75 0.5 1 1.5 2 2.5 3 3.5 VOUT (V) 4 4.5 5 3.50 5.5 4.04 4.03 4V OV THRESHOLD (V) 2V OV THRESHOLD (V) 1V OV THRESHOLD (V) 2.01 2.00 1.99 1.98 0 3.98 MEASUREMENT ERROR (mA) 0.4 0.2 0 –0.2 –0.4 –0.
LTC3883/LTC3883-1 Typical Performance Characteristics DC Output Current Matching in a 2-Phase System (LTC3883) Dynamic Current Sharing During a Load Transient in a 2-Phase System Dynamic Current Sharing During a Load Transient in a 2-Phase System 25 CHANNEL CURRENT (A) 20 CURRENT 5A/DIV 15 10 VIN = 12V VOUT = 1.8V fSW = 500kHz L = 0.4µH 15A TO 5A LOAD STEP 5µs/DIV 3883 G29 CURRENT 5A/DIV VIN = 12V VOUT = 1.8V fSW = 500kHz L = 0.
LTC3883/LTC3883-1 Pin Functions FREQ_CFG (Pin 14): Frequency or Phase Set/Select Pin. Connect a ±1% resistor divider between the chip VDD25 FREQ_CFG and GND in order to select switching frequency or phase. If the pin is left open, the IC will use the value programmed in the NVM. Minimize capacitance when the pin is open to assure accurate detection of the pin state. VOUT_CFG (Pin 15): Output Voltage Select Pin.
LTC3883/LTC3883-1 Block Diagram RIINSNS VIN + RVIN VIN CIN 1Ω 28 CVIN IIN_SNS VIN_SNS 1 2 5V REG LTC3883 ONLY INTVCC/EXTVCC (LTC3883-1) INTVCC /EXTVCC 27 + – VDD33 3.3V SUBREG IIN 19.5R R S R Q PWM_CLOCK ICMP 38R R – + 3k + – VDD33 21 BOOST DB 24 IREV TG 23 FCNT SWITCH LOGIC AND ANTISHOOTTHROUGH UV UVLO SS ILIM RANGE SELECT HI: 1:1 LO: 1:1.5 M1 SW 22 ON REV CB ISENSE+ 3 ISENSE– + 4 RUN BG OV VOUT COUT M2 26 CINTVCC 25 SLOPE COMPENSATION VSTBY 1.
LTC3883/LTC3883-1 Operation Overview The LTC3883 is a constant frequency, analog current mode controller for DC/DC step-down applications with a digital interface. The LTC3883 digital interface is compatible with PMBus which supports bus speeds of up to 400kHz. A typical application circuit is shown on the first page of this data sheet.
LTC3883/LTC3883-1 Operation with the resistor configuration pins detailed in Tables 12 and 13 or by the VOUT command (either from NVM or by PMBus command). Refer to the PMBus command section of the data sheet or the PMBus specification for more details. The output voltage can be modified by the user at any time with a PMBus VOUT_COMMAND. This command will typically have a latency less than 10ms.
LTC3883/LTC3883-1 Operation internal 5V linear regulator. The EXTVCC pin is driven by an external regulator to improve efficiency of the circuit and minimize power on the LTC3883. The EXTVCC pin must exceed approximately 4V before the internal UVLO is exceeded. To minimize application power, the EXTVCC pin can be supplied by a switching regulator. During initialization, the external configuration resistors are identified and/or contents of the NVM are read into the controller’s commands.
LTC3883/LTC3883-1 Operation PMBus command to turn on, or the VIN pin voltage rising above a preprogrammed voltage. Off sequencing is handled in a similar way. To assure proper sequencing, make sure all ICs connect the SHARE_CLK pins together and RUN pins together. If the RUN pins can not be connected together for some reason, set bit 2 of MFR_CHAN_CONFIG_LTC3883 to a 1. This bit requires the SHARE_CLK pin to be clocking before the power supply output can start.
LTC3883/LTC3883-1 Operation delay. If the natural decay time of the output is too long, it is possible to remove the voltage requirement of the MFR_RETRY_DELAY command by asserting bit 0 of MFR_CHAN_CONFIG_LTC3883. Alternatively, the controller can be configured so that it remains latched-off following a fault and clearing requires user intervention such as toggling RUN or commanding the part OFF then ON.
LTC3883/LTC3883-1 Operation the SYNC pin will pull low at the desired clock rate with 500ns low pulse. Care must be taken in the application to assure the capacitance on SYNC is minimized to assure the pull-up resistor versus the capacitor load has a low enough time constant for the application. In addition, a phase-locked loop (PLL) is available to synchronize the internal oscillator to an external clock source that is connected to the SYNC pin.
LTC3883/LTC3883-1 Operation command. The resulting measured powerstage current is returned by the READ_IIN command. The MFR_READ_IIN_CHAN command returns the calculated powerstage current based on the READ_IOUT value multiplied by the READ_DUTY_CYCLE value. The LTC3883 uses an internal 1Ω sense resistor to measure the VIN pin supply current being consumed by the LTC3883. This value is returned by the MFR_READ_ICHIP command.
LTC3883/LTC3883-1 Operation RCONFIG (Resistor Configuration) Pins TSNS LTC3883 GND GND 10nF MMBT3906 3883 F04 Figure 4. Temperature Sense Circuit temperature is calculated from the ∆VBE measurement. The external transistor temperature is digitized by the telemetry ADC, and the value is returned by the PMBus READ_ TEMPERATURE_1 command. The READ_TEMPERATURE_2 command returns the junction temperature of the LTC3883 using an on-chip diode.
LTC3883/LTC3883-1 Operation mode (FREQ_CFG pin shorted to ground). If no external clock is supplied, the part will clock at the lowest freerunning frequency of the internal PWM oscillator. This low clock rate will increase the ripple current of the inductor possibly producing undesirable operation. If the external SYNC signal is missing or misbehaving, a “PLL Lock Status” fault will be indicated in the STATUS_MFR_SPECIFIC command.
LTC3883/LTC3883-1 Operation to the regulator components by repetitive power cycling, assuming the fault condition itself is not immediately destructive. The MFR_RETRY_DELAY must be greater than 120ms. It can not exceed 83.88 seconds. The GPIO pin of the LTC3883 can share faults with all LTC PMBus products including the LTC3880, LTC2974, LTC2978, LTC4676 µModule, etc. In the event of an internal fault, one or more of the LTC3883s is configured to pull the bussed GPIO pins low.
LTC3883/LTC3883-1 OPERATION by a combination of the ASEL configuration pin and the MFR_ADDRESS command. Device addressing can be disabled by writing a value of 0x80 to the MFR_ADDRESS. Rail addressing provides a means of the PMBus master addressing a set of LTC3883s connected to the same output rail, simultaneously. This is similar to global addressing, however, the PMBus address can be dynamically assigned by using the MFR_RAIL_ADDRESS command.
LTC3883/LTC3883-1 OPERATION The overcurrent fault processing circuitry can execute the following behaviors: n n n Current Limit Indefinitely Shut Down Immediately—Latch Off Shut Down Immediately—Retry Indefinitely at the Time Interval Specified in MFR_RETRY_DELAY The overcurrent responses can be deglitched in increments of (0-7) • 16ms. See Table 7 Responses to Timing Faults TON_MAX_FAULT_LIMIT is the time allowed for VOUT to rise and settle at start-up.
LTC3883/LTC3883-1 OPERATION Responses To Input Overcurrent And Output Undercurrent Faults Input overcurrent and output undercurrent are measured with the MUX’d ADC. Both of these measurements are naturally deglitched by the 120ms typical response time of the ADC. The fault responses are: n n n Ignore Shut Down Immediately—Latch Off Shut Down Immediately—Retry Indefinitely at the Time Interval Specified in MFR_RETRY_DELAY See Table 9.
LTC3883/LTC3883-1 OPERATION SMBus/PMBus reads. If a general purpose I2C controller is used, check that repeat start is supported. The following PMBus protocols are supported: The LTC3883 supports the maximum SMBus clock speed of 100kHz and is compatible with the higher speed PMBus specification (between 100kHz and 400kHz) if clock stretching is enabled. For robust communication and operation refer to the Note section in the PMBus command summary.
LTC3883/LTC3883-1 OPERATION The data formats implemented by PMBus are: n n n Master transmitter transmits to slave receiver. The transfer direction in this case is not changed. Master reads slave immediately after the first byte. At the moment of the first acknowledgment (provided by the slave receiver) the master transmitter becomes a master receiver and the slave receiver becomes a slave transmitter. Combined format.
LTC3883/LTC3883-1 OPERATION 1 S 1 1 SLAVE ADDRESS Wr A COMMAND CODE A 7 1 1 8 P 3883 F11 Figure 11. Send Byte Protocol 1 S 7 1 1 8 1 SLAVE ADDRESS Wr A COMMAND CODE A 8 1 1 PEC A P 3883 F12 Figure 12. Send Byte Protocol with PEC 1 S 1 1 SLAVE ADDRESS Wr A COMMAND CODE A 7 1 1 8 S 7 1 1 SLAVE ADDRESS Rd A 8 1 DATA BYTE LOW A 1 1 DATA BYTE HIGH A 8 P 1 3883 F13 Figure 13.
LTC3883/LTC3883-1 PMBus Command Summary PMBus Commands The following tables list supported PMBus commands and manufacturer specific commands. A complete description of these commands can be found in the “PMBus Power System Mgt Protocol Specification – Part II – Revision 1.1”. Users are encouraged to reference this specification. Exceptions or manufacturer specific implementations are listed below in Table 2.
LTC3883/LTC3883-1 PMBus Command Summary COMMAND NAME CMD CODE DESCRIPTION TYPE DATA FORMAT UNITS NVM DEFAULT VALUE PAGE VIN_ON 0x35 Input voltage at which the unit should start power conversion. R/W Word L11 V Y 6.5 0xCB40 71 VIN_OFF 0x36 Input voltage at which the unit should stop power conversion. R/W Word L11 V Y 6.0 0xCB00 71 IOUT_CAL_GAIN 0x38 The ratio of the voltage at the current sense pins to the sensed current.
LTC3883/LTC3883-1 PMBus Command Summary COMMAND NAME CMD CODE DESCRIPTION TYPE DATA FORMAT UNITS NVM DEFAULT VALUE PAGE TON_RISE 0x61 Time from when the output starts to rise until the R/W Word output voltage reaches the VOUT commanded value. L11 ms Y 8.0 0xD200 80 TON_MAX_FAULT_LIMIT 0x62 Maximum time from VOUT_EN on for VOUT to cross the VOUT_UV_FAULT_LIMIT. R/W Word L11 ms Y 10.
LTC3883/LTC3883-1 PMBus Command Summary COMMAND NAME CMD CODE DESCRIPTION TYPE DATA FORMAT NVM DEFAULT VALUE USER_DATA_04 0xB4 An NVM word available for the user. R/W Word Reg PAGE Y 0x0000 90 MFR_T_SELF_HEAT 0xB8 Reports the calculated self heat value attributed to the inductor. R Word L11 C NA 75 MFR_IOUT_CAL_GAIN_ TAU_INV 0xB9 Coefficient used to emulate thermal time constant. R/W Word L11 s–1 Y 0.
LTC3883/LTC3883-1 PMBus Command Summary COMMAND NAME CMD CODE DESCRIPTION TYPE DATA FORMAT UNITS NVM DEFAULT VALUE PAGE MFR_FAULT_LOG_STORE 0xEA Command a transfer of the fault log from RAM to EEPROM. This causes the part to behave as if a channel has faulted off. Send Byte NA 101 MFR_FAULT_LOG_CLEAR 0xEC Initialize the EEPROM block reserved for fault logging and clear any previous fault logging locks.
LTC3883/LTC3883-1 PMBus Command Summary *Data Format L11 Linear_5s_11s PMBus data field b[15:0] Value = Y • 2N where N = b[15:11] is a 5-bit two’s complement integer and Y = b[10:0] is an 11-bit two’s complement integer Example: For b[15:0] = 0x9807 = ‘b10011_000_0000_0111 Value = 7 • 2–13 = 854 • 10–6 From “PMBus Spec Part II: Paragraph 7.
LTC3883/LTC3883-1 Applications Information The Typical Application on the back page is a basic LTC3883 application circuit. The LTC3883 can be configured to use either DCR (inductor resistance) sensing or low value resistor sensing. The choice between the two current sensing schemes is largely a design trade-off between cost, power consumption and accuracy.
LTC3883/LTC3883-1 Applications Information coupling into sensitive small-signal nodes. The capacitor C1 should be placed close to the IC pins. This impedance difference can result in loss of accuracy in the current reading of the ADC. The current reading accuracy can be improved by matching the impedance of the two pins. To accomplish this add a series resistor between VOUT and ISENSE– equal to R1. A capacitor of 1µF or greater should be placed in parallel with this resistor.
LTC3883/LTC3883-1 Applications Information purely inductive component. It was measured using two scope probes and waveform math to obtain a differential measurement. Based on additional measurements of the inductor ripple current and the on-time, tON, and off-time, tOFF, of the top switch, the value of the parasitic inductance was determined to be 0.
LTC3883/LTC3883-1 Applications Information Next, determine the DCR of the inductor. Where provided, use the manufacturer’s maximum value, usually given at 20°C. Increase this value to account for errors in the temperature sensing element of 3°C to 5°C and any additional errors associated with the proximity of the temperature sensor element to the inductor. C1 is usually selected to be in the range of 0.047µF to 4.7µF. This forces (R1 + R3)||R2 to be approximately 2k.
LTC3883/LTC3883-1 Applications Information Inductor Core Selection Once the inductor value is determined, the type of inductor must be selected. Core loss is independent of core size for a fixed inductor value, but it is very dependent on inductance. As the inductance increases, core losses go down. Unfortunately, increased inductance requires more turns of wire and therefore copper losses increase.
LTC3883/LTC3883-1 Applications Information The optional Schottky diodes conduct during the dead time between the conduction of the two power MOSFETs. These prevent the body diodes of the bottom MOSFETs from turning on, storing charge during the dead time and requiring a reverse recovery period that could cost as much as 3% in efficiency at high VIN. A 1A to 3A Schottky is generally a good compromise for both regions of operation due to the relatively small average current.
LTC3883/LTC3883-1 Applications Information Digital Servo Mode For maximum accuracy in the regulated output voltage, enable the digital servo loop by asserting bit 6 of the MFR_PWM_MODE_LTC3883 command. In digital servo mode, the LTC3883 will adjust the regulated output voltage based on the ADC voltage reading. Every 90ms the digital servo loop will step the LSB of the DAC (nominally 1.375mV or 0.6875mV depending on the voltage range bit) until the output is at the correct ADC reading.
LTC3883/LTC3883-1 Applications Information sufficient current to assure the output is a zero volts by the end of the fall time interval. If the TOFF_FALL time is set shorter than the time required to discharge the load capacitance, the output will not reach the desired zero volt state. At the end of TOFF_FALL, the controller will cease to sink current and VOUT will decay at the natural rate determined by the load impedance.
LTC3883/LTC3883-1 Applications Information voltage exceeds the RDS(ON) test voltage for the MOSFETs which is typically 4.5V for logic level devices. The UVLO on INTVCC (EXTVCC) is set to approximately 4V. Both the LTC3883 and LTC3883-1 are valid for this configuration. Topside MOSFET Driver Supply (CB, DB) External bootstrap capacitors CB connected to the BOOST pin supplies the gate drive voltages for the topside MOSFETs.
LTC3883/LTC3883-1 Applications Information maximum RMS current of one channel must be used. The maximum RMS capacitor current is given by: CIN Required IRMS ≈ 1/2 IMAX ⎡ ⎣( VOUT ) ( VIN – VOUT )⎤⎦ VIN This formula has a maximum at VIN = 2VOUT, where IRMS = IOUT/2. This simple worst-case condition is commonly used for design because even significant deviations do not offer much relief. Note that capacitor manufacturers’ ripple current ratings are often based on only 2000 hours of life.
LTC3883/LTC3883-1 Applications Information Open-Drain Pins The LTC3883 has the following open-drain pins: 3.3V Pins 1. GPIO 2. SYNC 3. SHARE_CLK 4. PGOOD 5V Pins (5V pins operate correctly when pulled to 3.3V.) 1. RUN 2. ALERT 3. SCL 4. SDA All the above pins have on-chip pull-down transistors that can sink 3mA at 0.4V. The low threshold on the pins is 1.4V; thus, plenty of margin on the digital signals with 3mA of current. For 3.3V pins, 3mA of current is a 1.1k resistor.
LTC3883/LTC3883-1 Applications Information If the SYNC signal is not clocking in the application, the PLL will run at the lowest free running frequency of the VCO. This will be well below the intended PWM frequency of the application and may cause undesirable operation of the converter. If the PWM signal appears to be running at too high a frequency, monitor the SYNC pin. Extra transitions on the falling edge will result in the PLL trying to lock on to noise versus the intended signal.
LTC3883/LTC3883-1 Applications Information Both the VIN_SNS and IIN_SNS pins need to be filtered with a 1% tolerance 100Ω resistor to RIINSNS and a 10nF ceramic capacitor to GND. A larger value capacitor to GND may be used for additional filtering. Because the input current sense amplifier gain is calibrated for 100Ω filter resistors, any other filter resistance value will cause an input current measurement error.
LTC3883/LTC3883-1 Applications Information Table 12. VOUT_CFG Table 13. VTRIM_CFG RTOP (kΩ) RBOTTOM (kΩ) VOUT (V) 0 or Open Open NVM 10 23.2 See VTRIM 10 15.8 3.3 16.2 20.5 3.1 16.2 17.4 2.9 20 17.8 2.7 20 15 2.5 20 12.7 2.3 20 11 2.1 24.9 11.3 1.9 24.9 9.09 1.7 24.9 7.32 1.5 24.9 5.76 1.3 24.9 4.32 1.1 30.1 3.57 0.9 30.1 1.96 0.7 Open 0 0.5 VTRIM (mV) CHANGE TO VSET VOLTAGE RTOP (kΩ) RBOTTOM (kΩ) 0 or Open Open 0 10 23.2 99 10 15.8 86.
LTC3883/LTC3883-1 Applications Information Frequency and Phase Selection Using RCONFIG The frequency and phase commands are linked if they are set using the RCONFIG pins. If PMBus commands are used the two parameters are independent. The SYNC pins must be shared in poly-phase configurations where multiple LTC3883s are used to produce the output. If the configuration is not PolyPhase the SYNC pins do not have to be shared.
LTC3883/LTC3883-1 Applications Information Efficiency Considerations The percent efficiency of a switching regulator is equal to the output power divided by the input power times 100%. It is often useful to analyze individual losses to determine what is limiting the efficiency and which change would produce the most improvement. Percent efficiency can be expressed as: %Efficiency = 100% – (L1 + L2 + L3 + ...) where L1, L2, etc. are the individual losses as a percentage of input power.
LTC3883/LTC3883-1 Applications Information load current. When a load step occurs, VOUT shifts by an amount equal to ∆ILOAD (ESR), where ESR is the effective series resistance of COUT . ∆ILOAD also begins to charge or discharge COUT generating the feedback error signal that forces the regulator to adapt to the current change and return VOUT to its steady-state value. During this recovery time VOUT can be monitored for excessive overshoot or ringing, which would indicate a stability problem.
LTC3883/LTC3883-1 Applications Information When connecting a 3-phase LTC3883/LTC3880, the VIN pin and power stage of the LTC3880 should be connected to the downstream side of the LTC3883 input current sense resistor. This allows the user to measure the total input current of the rail. Refer to the Typical Application circuit: High Efficiency 3-Phase 350kHz 1.8V Step-Down Converter with Input Current Sense. The inductor DCR for all three inductors of LTC3883/LTC3880 application can be calculated.
LTC3883/LTC3883-1 Applications Information RIINSNS VIN RIIN RIIN IIN_SNS TSNS VIN_SNS Q1 LTC3883 C1 RVIN ISENSE+ ISENSE– VIN CVIN L TG SW CB BOOST SYNC RUN VSENSE+ VSENSE– 1µF CERAMIC INTVCC ITH GND GND + CINTVCC CIN VOUT M2 D1 COUT + + VDD33 VDD25 M1 BG RSENSE 3883 F26 Figure 26. Recommended Printed Circuit Layout Diagram RIN SW RSENSEIN VIN CIN L D RSENSE VOUT COUT RL 3883 F27 BOLD LINES INDICATE HIGH SWITCHING CURRENT. KEEP LINES TO A MINIMUM LENGTH.
LTC3883/LTC3883-1 Applications Information 6. Use a modified “star ground” technique: a low impedance, large copper area central grounding point on the same side of the PC board as the input and output capacitors with tie-ins for the bottom of the INTVCC decoupling capacitor, the bottom of the voltage feedback resistive divider and the GND pin of the IC. 7.
LTC3883/LTC3883-1 Applications Information 5mΩ VIN 6V TO 20V 10µF D4 INTVCC 1µF 100Ω 10nF TG 100Ω LTC3883 BOOST IIN_SNS VIN_SNS 10nF 22µF 50V 1µF M1 0.1µF 1.0µH SW M2 BG PGND 3Ω 10k 10µF 10k PMBus INTERFACE 10k 10k 10k 10k 10k 5k VDD33 FREQ_CFG VIN PGOOD VOUT_CFG SDA VTRIM_CFG SCL ASEL WP ALERT RUN SHARE_CLK ISENSE+ GPIO ISENSE– SYNC VSENSE+ VDD25 VSENSE– VDD33 TSNS GND 1.0µF 2.2k 0.2µF ITH 1.0µF + MMBT3906 2200pF 3883 F28 10nF 6.04k VOUT 3.
LTC3883/LTC3883-1 Applications Information The maximum power loss in R0 is related to the duty cycle, and will occur in continuous mode at the maximum input voltage: PLOSSR1= The current limit will be set 20% higher than the peak value to assure variation in components and noise in the system do not limit the average current. VILIMIT = IPEAK • RDCR(MAX) = 17.39A • 2.5mΩ = 43mV The closest VILIMIT setting is 42.9mV or 46.4mV. The values are entered with the IOUT_OC_FAULT_LIMIT command.
LTC3883/LTC3883-1 Applications Information VIN LTC CONTROLLER HEADER ISOLATED 3.3V SDA 100k 100k VIN VDD33 TP0101K SCL 1µF 10k VDD25 LTC3883 1µF SDA 10k SCL WP SGND TO LTC DC1613 USB TO I2C/SMBus/PMBus CONTROLLER VIN TP0101K VDD33 1µF VDD25 LTC3883 1µF SDA VGS MAX ON THE TP0101K IS 8V IF VIN > 16V CHANGE THE RESISTOR DIVIDER ON THE PFET GATE SCL WP SGND 3883 F29 Figure 29.
LTC3883/LTC3883-1 Applications Information Accurate DCR Temperature Compensation Using the DC resistance of the inductor as a current shunt element has several advantages—no additional power loss, lower circuit complexity and cost. However, the strong temperature dependence of the inductor resistance and the difficulty in measuring the exact inductor core temperature introduce errors in the current measurement. For copper, a change of inductor temperature of only 1°C corresponds to approximately 0.
LTC3883/LTC3883-1 Applications Information the accuracy in calculating θIS, the two load currents should be chosen around I1 = 10% and I2 = 90% of the current range of the system. The inductor thermal time constant τ models the first order thermal response of the inductor and allows accurate DCR compensation during load transients. During a transition from low-to-high load current, the inductor resistance increases due to the self-heating.
LTC3883/LTC3883-1 Applications Information Figure 31. LTpowerPlay Screen Shot CMD PMBus WRITE WRITE COMMAND DATA BUFFER DECODER CMDS DATA MUX CALCULATIONS PENDING S R PAGE • • • VOUT_COMMAND 0x00 0x21 • • • MFR_RESET INTERNAL PROCESSOR FETCH, CONVERT DATA AND EXECUTE 0xFD x1 3883 F32 Figure 32. Write Command Data Processing Command data buffering handles incoming PMBus writes by storing the command data to the Write Command Data Buffer and marking these commands for future processing.
LTC3883/LTC3883-1 Applications Information When the part receives a new command while it is busy, it will communicate this condition using standard PMBus protocol. Depending on part configuration it may either NACK the command or return all ones (0xFF) for reads. It may also generate a BUSY fault and ALERT notification, or stretch the SCL clock low. For more information refer to PMBus Specification v1.1, Part II, Section 10.8.7 and SMBus v2.0 section 4.3.3.
LTC3883/LTC3883-1 PMBus Command Details Addressing and Write Protect COMMAND NAME PAGE WRITE_PROTECT MFR_ADDRESS MFR_RAIL_ADDRESS CMD CODE DESCRIPTION 0x00 Provides integration with multi-page PMBus devices. 0x10 Level of protection provided by the device against accidental changes. 0xE6 Sets the 7-bit I2C address byte. 0xFA Common address for PolyPhase outputs to adjust common parameters.
LTC3883/LTC3883-1 PMBus Command Details MFR_ADDRESS The MFR_ADDRESS command byte sets the 7 bits of the PMBus slave address for this device. Setting this command to a value of 0x80 disables device addressing. The GLOBAL device address, 0x5A and 0x5B, cannot be deactivated. If RCONFIG is set to ignore, the ASEL pin is still used to determine the LSB of the channel address. If the ASEL pin is open, the LTC3883 will use the address value stored in NVM. This command has one data byte.
LTC3883/LTC3883-1 PMBus Command Details MFR_CONFIG_ALL_LTC3883 General purpose configuration command common to multiple LTC products BIT MEANING 7 Enable Fault Logging 6 Ignore Resistor Configuration Pins 5 Reserved 4 Reserved 3 Mask PLL Unlock Fault 2 A valid PEC required for PMBus writes to be accepted. If this bit is not set, the part will accept commands with invalid PEC. 1 Enable the use of PMBus clock stretching 0 Reserved This command has one data byte.
LTC3883/LTC3883-1 PMBus Command Details Table 3. ON_OFF_CONFIG Detailed Command Information ON_OFF_CONFIG Data Contents BITS(S) SYMBOL OPERATION b[7:5] Reserved b[3] Don’t care. Always returns 0. On_off_config_use_pmbus Controls how the unit responds to commands received via the serial bus. 0: Unit ignores the Operation command b[7:6]. 1: Unit responds to Operation command b[7:6]. The unit also requires the RUN pin to be asserted for the unit to start.
LTC3883/LTC3883-1 PMBus Command Details MFR_RESET This command provides a means by which the user can perform a reset of the LTC3883. This write-only command has no data bytes. PWM Configuration COMMAND NAME CMD CODE DESCRIPTION TYPE DATA DEFAULT FORMAT UNITS NVM VALUE MFR_PWM_MODE_ LTC3883 0xD4 Configuration for the PWM engine. R/W Byte Reg Y 0xD2 MFR_PWM_CONFIG_ LTC3883 0xF5 Set numerous parameters for the DC/DC controller including phasing.
LTC3883/LTC3883-1 PMBus Command Details Bit[3] Setting this bit to a 1 starts the patent pending inductor DCR auto calibration to determine the DCR of the inductor. This will update the value of IOUT_CAL_GAIN using the READ_IIN, READ_IOUT, and DUTY_CYCLE values. IOUT_CAL_GAIN is adjusted so that READ_IOUT • DUTY_CYCLE = READ_IIN. The auto calibration procedure will only complete successfully if the following conditions are met.
LTC3883/LTC3883-1 PMBus Command Details FREQUENCY_SWITCH The FREQUENCY_SWITCH command sets the switching frequency, in kHz, of a PMBus device. Supported Frequencies: VALUE [15:0] 0x0000 0xF3E8 0xFABC 0xFB52 0xFBE8 0x023F 0x028A 0x02EE 0x03E8 RESULTING FREQUENCY (TYP) External Oscillator 250kHz 350kHz 425kHz 500kHz 575kHz 650kHz 750kHz 1000kHz The part must be in the OFF state to process this command. The RUN pin must be low or the part must be commanded off.
LTC3883/LTC3883-1 PMBus Command Details VIN_ON The VIN_ON command sets the input voltage, in volts, at which the unit should start power conversion. This command has two data bytes and is formatted in Linear_5s_11s format. VIN_OFF The VIN_OFF command sets the input voltage, in volts, at which the unit should stop power conversion. This command has two data bytes and is formatted in Linear_5s_11s format.
LTC3883/LTC3883-1 PMBus Command Details VOUT_MAX The VOUT_MAX command sets an upper limit on the output voltage, in volts, the unit can command regardless of any other commands or combinations. This command has two data bytes and is formatted in Linear_16u format. VOUT_OV_FAULT_LIMIT The VOUT_OV_FAULT_LIMIT command sets the value of the output voltage measured at the sense pins, in volts, which causes an output overvoltage fault.
LTC3883/LTC3883-1 PMBus Command Details VOUT_COMMAND The VOUT_COMMAND consists of two bytes and is used to set the output voltage, in volts. This command will not be acted on during TON_RISE and TOFF_FALL output sequencing. The VOUT_TRANSITION_RATE will be used if this command is modified while the output is active and in a steady-state condition. This command has two data bytes and is formatted in Linear_16u format.
LTC3883/LTC3883-1 PMBus Command Details POWER_GOOD_OFF The POWER_GOOD_OFF command sets the output voltage at which the POWER_GOOD# status bit in the STATUS_WORD command should be asserted. POWER_GOOD_OFF is detected with an A/D read resulting in latency of up to 120ms. The POWER_GOOD_OFF value must be set lower than the POWER_GOOD_ON value. At initial power up the state of the PGOOD pin will be high regardless of VOUT.
LTC3883/LTC3883-1 PMBus Command Details This command has two data bytes and is formatted in 16-bit 2’s complement integer ppm. N = –32768 to 32767 • 10–6. Nominal temperature is 27°C. The IOUT_CAL_GAIN is multiplied by: [1.0 + MFR_IOUT_CAL_GAIN_TC • (READ_TEMPERATURE_1‑27)]. DCR sensing will have a typical value of 3900. The IOUT_CAL_GAIN and MFR_IOUT_CAL_GAIN_TC impact all current parameters including: READ_IOUT, MFR_ READ_IIN_CHAN, IOUT_OC_FAULT_LIMIT and IOUT_OC_WARN_LIMIT.
LTC3883/LTC3883-1 PMBus Command Details The actual value of Cτ is not required. The important quantity is the thermal time constant τINV = (θIS Cτ). For example, if an inductor has a thermal time constant τTHERMAL = 5 seconds then: MFR_IOUT_CAL_GAIN_TAU_INV = ∆t / τTHERMAL = 1/5 = 0.2 Refer to the application section for more information on calibrating θIS and τINV.
LTC3883/LTC3883-1 PMBus Command Details IOUT_OC_FAULT_LIMIT The IOUT_OC_FAULT_LIMIT command sets the value of the peak output current limit, in amperes. When the controller is in current limit, the overcurrent detector will indicate an overcurrent fault condition. The programmed overcurrent fault limit value is rounded up to the nearest one of the following set of discrete values: 25mV/IOUT_CAL_GAIN 28.6mV/IOUT_CAL_GAIN 32.1mV/IOUT_CAL_GAIN 35.7mV/IOUT_CAL_GAIN 39.3mV/IOUT_CAL_GAIN 42.9mV/IOUT_CAL_GAIN 46.
LTC3883/LTC3883-1 PMBus Command Details Input Current Calibration COMMAND NAME MFR_IIN_CAL_GAIN CMD CODE DESCRIPTION 0xE8 The resistance value of the input current sense element in mΩ. TYPE R/W Word DATA FORMAT L11 UNITS mΩ NVM Y DEFAULT VALUE 5.000 0xCA80 MFR_IIN_CAL_GAIN The IOUT_CAL_GAIN command is used to set the resistance value of the input current sense resistor in milliohms. (see also READ_IIN). This command has two data bytes and is formatted in Linear_5s_11s format.
LTC3883/LTC3883-1 PMBus Command Details MFR_TEMP_1_OFFSET The MFR_TEMP_1_OFFSET command will modify the offset of the external temperature sensor to account for nonidealities in the element and errors associated with the remote sensing of the temperature in the inductor. This command has two data bytes and is formatted in Linear_5s_11s format. The part starts the calculation with a value of –273.15 so the default adjustment value is zero.
LTC3883/LTC3883-1 PMBus Command Details Timing Timing—On Sequence/Ramp COMMAND NAME TON_DELAY CMD CODE DESCRIPTION 0x60 Time from RUN and/or Operation on to output rail turn-on. TON_RISE 0x61 Time from when the output starts to rise until the output voltage reaches the VOUT commanded value. TON_MAX_FAULT_LIMIT 0x62 Maximum time from VOUT_EN on for VOUT to cross the VOUT_UV_FAULT_LIMIT. VOUT_TRANSITION_RATE 0x27 Rate the output changes when VOUT commanded to a new value.
LTC3883/LTC3883-1 PMBus Command Details Timing—Off Sequence/Ramp COMMAND NAME TOFF_DELAY TOFF_FALL TOFF_MAX_WARN_LIMIT CMD CODE DESCRIPTION TYPE 0x64 Time from RUN and/or Operation off to the start R/W Word of TOFF_FALL ramp. 0x65 Time from when the output starts to fall until the R/W Word output reaches zero volts. 0x66 Maximum allowed time, after TOFF_FALL R/W Word completed, for the unit to decay below 12.5%. DATA FORMAT L11 UNITS ms NVM Y L11 ms Y L11 ms Y DEFAULT VALUE 0.0 0x8000 8.
LTC3883/LTC3883-1 PMBus Command Details MFR_RESTART_DELAY This command specifies the minimum RUN off time in milliseconds. This device will pull the RUN pin low for this length of time once a falling edge of RUN has been detected. The minimum recommended value is 136ms. Note: The restart delay is different than the retry delay. The restart delay pulls RUN low for the specified time, after which a standard start-up sequence is initiated.
LTC3883/LTC3883-1 PMBus Command Details • Sets the VIN Overvoltage Fault bit in the STATUS_INPUT command, and • Notifies the host by asserting ALERT pin This command has one data byte. Fault Responses Output Voltage COMMAND NAME CMD CODE DESCRIPTION TYPE DATA FORMAT UNITS NVM DEFAULT VALUE VOUT_OV_FAULT_RESPONSE 0x41 Action to be taken by the device when an output overvoltage fault is detected.
LTC3883/LTC3883-1 PMBus Command Details Table 5. VOUT_OV_FAULT_RESPONSE Data Byte Contents BITS 7:6 DESCRIPTION Response VALUE 00 For all values of bits [7:6], the LTC3883: • Sets the corresponding fault bit in the status commands and • Notifies the host by asserting ALERT pin 01 The fault bit, once set, is cleared only when one or more of the following events occurs: • The device receives a CLEAR_FAULTS command.
LTC3883/LTC3883-1 PMBus Command Details Table 6. VOUT_UV_FAULT_RESPONSE Data Byte Contents BITS 7:6 DESCRIPTION VALUE Response MEANING 00 The PMBus device continues operation without interruption. (Ignores the fault functionally) 01 The PMBus device continues operation for the delay time specified by bits [2:0] and the delay time unit specified for that particular fault.
LTC3883/LTC3883-1 PMBus Command Details IOUT_OC_FAULT_RESPONSE The IOUT_OC_FAULT_RESPONSE command instructs the device on what action to take in response to an output overcurrent fault. The data byte is in the format given in Table 7.
LTC3883/LTC3883-1 PMBus Command Details MFR_OT_FAULT_RESPONSE The MFR_OT_FAULT_RESPONSE command byte instructs the device on what action to take in response to an internal overtemperature fault. The data byte is in the format given in Table 8. The LTC3883 also: • Sets the NONE_OF_THE_ABOVE bit in the STATUS_BYTE • Sets the MFR bit in the STATUS_WORD, and • Sets the Overtemperature Fault bit in the STATUS_MFR_SPECIFIC command • Notifies the host by asserting ALERT pin This command has one data byte. Table 8.
LTC3883/LTC3883-1 PMBus Command Details This condition is detected by the ADC so the response time may be up to 120ms. This command has one data byte. UT_FAULT_RESPONSE The UT_FAULT_RESPONSE command instructs the device on what action to take in response to an external undertemperature fault on the external temp sensors. The data byte is in the format given in Table 9.
LTC3883/LTC3883-1 PMBus Command Details MFR_GPIO_PROPAGATE_LTC3883 The MFR_GPIO_PROPAGATE_LTC3883 command enables the events that can cause the GPIO pin to assert low. The command is formatted as shown in Table 10. Faults can only be propagated to the GPIO pin if they are programmed to respond to faults. This command has two data bytes. Table 10: GPIO Propagate Configuration The GPIO pin is designed to provide electrical notification of selected events to the user.
LTC3883/LTC3883-1 PMBus Command Details Fault Sharing Response COMMAND NAME MFR_GPIO_RESPONSE CMD CODE DESCRIPTION TYPE 0xD5 Action to be taken by the device when the GPIO pin R/W Byte is asserted low. DATA FORMAT Reg UNITS NVM Y DEFAULT VALUE 0xC0 MFR_GPIO_RESPONSE This command determines the controller’s response to the GPIO pin being pulled low by an external source. VALUE 0xC0 0x00 MEANING GPIO_INHIBIT The LTC3883 will three-state the output in response to the GPIO pin pulled low.
LTC3883/LTC3883-1 PMBus Command Details PMBus_REVISION The PMBUS_REVISION command indicates the revision of the PMBus to which the device is compliant. The LTC3883 is PMBus Version 1.1 compliant in both Part I and Part II. This read-only command has one data byte. CAPABILITY This command provides a way for a host system to determine some key capabilities of a PMBus device. The LTC3883 supports packet error checking, 400kHz bus speeds, and ALERT pin. This read-only command has one data byte.
LTC3883/LTC3883-1 PMBus Command Details CLEAR_FAULTS The CLEAR_FAULTS command is used to clear any fault bits that have been set. This command clears all bits in all status commands simultaneously. At the same time, the device negates (clears, releases) its ALERT pin signal output if the device is asserting the ALERT pin signal. The CLEAR_FAULTS does not cause a unit that has latched off for a fault condition to restart.
LTC3883/LTC3883-1 PMBus Command Details This permits the user to clear status by means other than using the CLEAR_FAULTS command. These are also the only bits of this command that can initiate an ALERT event. [6] Bit 6 of this command will be set whenever the output is turned off. [11] Bit 11 of this command will be set whenever the output voltage is below the POWER_GOOD_OFF threshold. If any of the bits in the upper byte are set, NONE_OF_THE_ABOVE is asserted.
LTC3883/LTC3883-1 PMBus Command Details Only bits 7, 6 and 4 are supported in the LTC3883. The user is permitted to write a 1 to any bit in this command to clear a specific fault. This permits the user to clear status by means other than using the CLEAR_FAULTS command. Any supported fault bit in this command will initiate an ALERT event. This command has one data byte. STATUS_CML The STATUS_CML commands returns one byte with the status information on received commands and system memory/logic.
LTC3883/LTC3883-1 PMBus Command Details MFR_PADS This command provides the user a means of directly reading the digital status of the I/O pins of the device.
LTC3883/LTC3883-1 PMBus Command Details READ_IOUT READ_TEMPERATURE_1 0x8C 0x8D READ_TEMPERATURE_2 0x8E READ_DUTY_CYCLE READ_POUT READ_PIN MFR_IOUT_PEAK 0x94 0x96 0x97 0xD7 MFR_VOUT_PEAK 0xDD MFR_VIN_PEAK 0xDE MFR_TEMPERATURE_1_PEAK 0xDF MFR_READ_IIN_CHAN_PEAK 0xE1 MFR_READ_ICHIP MFR_READ_IIN_CHAN 0xE4 0xED MFR_TEMPERATURE_2_PEAK 0xF4 Measured output current. External diode junction temperature. This is the value used for all temperature related processing, including IOUT_CAL_GAIN.
LTC3883/LTC3883-1 PMBus Command Details Summary of the Status Commands STATUS_VOUT 7 6 5 4 3 2 1 0 VOUT OV Fault VOUT OV Warning VOUT UV Warning VOUT UV Fault VOUT MAX Warning TON MAX FAULT TOFF MAX Warning Reserved 7 6 5 4 3 2 1 0 IOUT_OC Fault Reserved IOUT_OC Warning Reserved Reserved Reserved Reserved Reserved 7 6 5 4 3 2 1 0 OT Fault OT Warning Reserved UT Fault Reserved Reserved Reserved Reserved 7 6 5 4 3 2 1 0 Invalid/Unsupported Command Invalid/Unsupported Data Packet Error Check Failed Memo
LTC3883/LTC3883-1 PMBus Command Details c) the MFR_IOUT_CAL_GAIN_TC value, and d) READ_TEMPERATURE_1 value e) The MFR_TEMP_1_GAIN and the MFR_TEMP_1_OFFSET f) The MFR_IOUT_CAL_GAIN_TAU_INV and MFR_IOUT_CAL_GAIN_THETA This read-only command has two data bytes and is formatted in Linear_5s_11s format. READ_TEMPERATURE_1 The READ_TEMPERATURE_1 command returns the temperature, in degrees Celsius, of the external sense element. This read-only command has two data bytes and is formatted in Linear_5s_11s format.
LTC3883/LTC3883-1 PMBus Command Details MFR_VIN_PEAK The MFR_VIN_PEAK command reports the highest voltage, in volts, reported by the READ_VIN measurement. This command is cleared using the MFR_CLEAR_PEAKS command. This read-only command has two data bytes and is formatted in Linear_5s_11s format. MFR_TEMPERATURE_1_PEAK The MFR_TEMPERATURE_1_PEAK command reports the highest temperature, in degrees Celsius, reported by the READ_TEMPERATURE_1 measurement.
LTC3883/LTC3883-1 PMBus Command Details NVM Memory Commands Store/Restore COMMAND NAME CMD CODE DESCRIPTION STORE_USER_ALL 0x15 Store user operating memory to EEPROM. Send Byte NA RESTORE_USER_ALL 0x16 Restore user operating memory from EEPROM. Send Byte NA MFR_COMPARE_USER_ALL 0xF0 Compares current command contents with NVM.
LTC3883/LTC3883-1 PMBus Command Details Fault Logging COMMAND NAME CMD CODE DESCRIPTION TYPE DATA FORMAT R Block CF UNITS NVM DEFAULT VALUE Y NA MFR_FAULT_LOG 0xEE Fault log data bytes. This sequentially retrieved data is used to assemble a complete fault log. MFR_FAULT_LOG_ STORE 0xEA Command a transfer of the fault log from RAM to Send Byte EEPROM. This causes the part to behave as if the PWM has faulted off.
LTC3883/LTC3883-1 PMBus Command Details MFR_REAL_TIME MFR_VOUT_PEAK Reserved Reserved MFR_IOUT_PEAK MFR_READ_IIN_CHAN_PEAK MFR_VIN_PEAK READ_TEMPERATURE_1 Reserved Reserved READ_TEMPERATURE_2 MFR_TEMPERATURE_1_PEAK [7:0] [15:8] [23:16] [31:24] [39:32] [47:40] [15:8] [7:0] [15:8] [7:0] [15:8] [7:0] [15:8] [7:0] [15:8] [7:0] [15:8] [7:0] [15:8] [7:0] Reserved Reserved CYCLICAL DATA EVENT n BYTE BYTE BYTE BYTE BYTE BYTE LIN 16 BYTE BYTE LIN 11 LIN 11 LIN 11 LIN 11 BYTE BYTE LIN 11 LIN 11 BYTE BYTE 1 2 3
LTC3883/LTC3883-1 PMBus Command Details MFR_READ_ICHIP STATUS_MFR_SPECIFIC Reserved EVENT n-1 [7:0] BYTE BYTE (data measured before fault was detected) READ_VOUT [15:8] [7:0] Reserved Reserved READ_IOUT [15:8] [7:0] MFR_READ_IIN_CHAN [15:8] [7:0] READ_VIN [15:8] [7:0] READ_IIN [15:8] [7:0] STATUS_VOUT Reserved STATUS_WORD [15:8] [7:0] Reserved Reserved STATUS_MFR_SPECIFIC Reserved * * * EVENT n-5 (Oldest Recorded Data) READ_VOUT Reserved Reserved READ_IOUT MFR_READ_IIN_CHAN READ_VIN READ_IIN STATUS_VOUT R
LTC3883/LTC3883-1 PMBus Command Details Reserved STATUS_MFR_SPECIFIC Reserved BYTE BYTE BYTE 144 145 146 Always returns 0x00. Always returns 0x00.
LTC3883/LTC3883-1 PMBus Command Details Writing 0x2B followed by 0xD5 sets the PEC, resets the EEPROM address pointer and unlocks the part for EEPROM erase and data command writes. Writing 0x2B followed by 0x91 and 0xE4 clears PEC, resets the EEPROM address pointer and unlocks the part for EEPROM data reads of all locations. Writing 0x2B followed by 0x91 and 0xE5 sets PEC, resets the EEPROM address pointer and unlocks the part for EEPROM data reads of all locations.
LTC3883/LTC3883-1 Typical Applications High Efficiency 500kHz 1.2V Step-Down Converter with External VCC 5mΩ VIN 6V TO 14V 5VIN 10µF EXTVCC 100Ω TG LTC3883-1 BOOST IIN_SNS 100Ω 1µF VIN_SNS 10nF 22µF 50V 1µF D1 M1 0.1µF 0.32µH SW 10nF M2 V DD25 BG 3Ω PGND VIN 10k 10µF 10k PMBus INTERFACE 10k 20k 1k 12.7k 4.32k 23.2k 1µF 17.8k VOUT_CFG SCL 10k 24.9k FREQ_CFG SDA 10k ALERT VTRIM_CFG 10k RUN 10k ASEL 1k 0.
LTC3883/LTC3883-1 Typical ApplicationS High Efficiency 425kHz 1V Step-Down Converter with Power Block 5mΩ VIN 7V TO 14V 10µF 22µF 50V 1µF 7V GATE DRIVE INTVCC 100Ω 1µF BOOST 100Ω IIN_SNS 3Ω 10nF 10nF VIN_SNS LTC3883 BG SW VIN 10µF 10k 10k PMBus INTERFACE 10k 10k 10k 10k 10k 5k VDD33 VIN PWMH VOUT P1 CS– VGATE CS+ TEMP+ PWML TEMP– GND TG SDA PGND SCL WP VDD25 SHARE_CLK ALERT RUN VTRIM_CFG PGOOD GPIO 24.9k 20k 16.2k 4.32k 17.8k 17.
LTC3883/LTC3883-1 Typical ApplicationS High Efficiency 500kHz 2-Phase 1.8V Step-Down Converter with Sense Resistors 5mΩ VIN 6V TO 18V 10µF INTVCC 100Ω 1µF TG LTC3883 BOOST IIN_SNS 100Ω VIN_SNS 10nF 3Ω 0.002Ω M2 BG 10k FREQ_CFG PGOOD VOUT_CFG 10k 10k SDA VTRIM_CFG SCL ASEL ALERT 10k VDD25 WP 20k 24.9k 17.8k 11.3k RUN 10k SHARE_CLK 10k VDD33 0.4µH PGND 10k PMBus INTERFACE M1 0.
LTC3883/LTC3883-1 Typical ApplicationS High Efficiency 3-Phase 425kHz 1.8V Step-Down Converter with Input Current Sense 5mΩ VIN 6V TO 14V 10µF 100Ω 1µF TG LTC3883 BOOST IIN_SNS 100Ω VIN_SNS 10nF L0 0.56µH M2 BG PGND 1.4k PGOOD 10k PMBus INTERFACE VDD25 VIN 10k 10µF 10k 10k SDA VOUT_CFG SCL VTRIM_CFG ALERT 10k GPIO 5k SYNC WP 1.0µF 17.8k ASEL 1.4k 0.22µF ISENSE+ ISENSE– VSENSE+ + TSNS ITH GND 1.0µF D2 VIN TG0 TG1 LTC3880 BOOST0 M4 0.1µF L2 0.
LTC3883/LTC3883-1 Package Description Please refer to http://www.linear.com/designtools/packaging/ for the most recent package drawings. UH Package 32-Lead Plastic QFN (5mm × 5mm) (Reference LTC DWG # 05-08-1693 Rev D) 0.70 ±0.05 5.50 ±0.05 4.10 ±0.05 3.50 REF (4 SIDES) 3.45 ± 0.05 3.45 ± 0.05 PACKAGE OUTLINE 0.25 ± 0.05 0.50 BSC RECOMMENDED SOLDER PAD LAYOUT APPLY SOLDER MASK TO AREAS THAT ARE NOT SOLDERED 5.00 ± 0.10 (4 SIDES) BOTTOM VIEW—EXPOSED PAD 0.75 ± 0.05 R = 0.05 TYP 0.00 – 0.05 R = 0.
LTC3883/LTC3883-1 Revision History REV DATE DESCRIPTION A 11/13 Changed VOUT range to 5.4V. Added patent number. PAGE NUMBER 1 Added SYNC to the Absolute Maximum Ratings. 4 Fixed conditions on the LSB step size. 6 Deleted "and," and added "The BG, TG and RUN pins are held low. The GPIO pin is in high impedance mode." 17 Deleted "ARA command..." 23, 24 Deleted five instances of "MFR_REGISTERS” 33, 35 Changed RUN to SHARE_CLK. Added text. 45 Deleted NVM.
LTC3883/LTC3883-1 Typical Application High Efficiency 500kHz 1.8V Step-Down Converter with DCR Sense 5mΩ VIN 6V TO 24V 10µF D1 INTVCC 100Ω 1µF TG LTC3883 BOOST IIN_SNS 100Ω 10nF VIN 10k 10k PMBus INTERFACE 10k 10k 10k 10k 10k 5k VDD33 M2 SDA 1µF 20k 24.9k 10k 20k 12.7k 9.09k 23.2k 17.8k FREQ_CFG SCL ALERT RUN 1.4k VDD25 PGOOD VOUT_CFG 1.4k VTRIM_CFG 0.22µF SHARE_CLK ASEL ISENSE+ GPIO ISENSE– SYNC VSENSE+ WP VSENSE– VDD25 VDD33 1.0µF 0.56µH BG PGND 10µF M1 0.
