LTC4417 Prioritized PowerPath™ Controller Description Features n n n n n n n n n n n n Selects Highest Priority Supply from Three Inputs Blocks Reverse and Cross Conduction Currents Wide Operating Voltage Range: 2.5V to 36V –42V Protection Against Reverse Battery Connection Fast Switchover Minimizes Output Voltage Droop Low 28µA Operating Current <1µA Current Draw from Supplies Less than VOUT 1.
LTC4417 Absolute Maximum Ratings (Notes 1, 2) Supply Voltages V1, V2, V3................................................ –42V to 42V VOUT, VS1, VS2, VS3............................... –0.3V to 42V Voltage from V1, V2, V3 to VOUT.................. –84V to 42V Voltage from VS1, VS2, VS3 to G1, G2, G3...................................................–0.3V to 7.5V Input Voltages EN, SHDN............................................... –0.3V to 42V OV1, OV2, OV3, UV1, UV2, UV3................ –0.3V to 6V HYS..
LTC4417 Electrical Characteristics The l denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25°C. For all tests, V1 = VS1, V2 = VS2, V3 = VS3. Unless otherwise noted, V1 = V2 = V3 = VOUT = 12V, HYS = GND. SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS Start-Up 36 V IV1-V3,VOUT(EN) Total Supply Current with Channels Enabled V1 = 5V, V2 = 12V, V3 = 2.
LTC4417 Electrical Characteristics The l denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25°C. For all tests, V1 = VS1, V2 = VS2, V3 = VS3. Unless otherwise noted, V1 = V2 = V3 = VOUT = 12V, HYS = GND. SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS 0.25 0.55 V 8 13 µs Input/Output Pins VVALID(OL) VALID1 to VALID3 Output Low Voltage tpVALID(OFF) VALID1 to VALID3 Delay OFF From OV/UV Fault I = 1mA, (V1 to V3) = 2.
LTC4417 Typical Performance Characteristics Total Shutdown Supply Current vs Supply Voltage Total Enabled Supply Current vs Supply Voltage 20 15 10 5 0 35 14 30 12 25 20 15 10 ALL SUPPLY, VS AND VOUT PINS CONNECTED TOGETHER 16 6.35 14 GATE FALLING SLEW RATE (V/µs) 6.40 ∆VG (V) 6.15 6.10 6.05 6.00 –50 –25 0 25 50 75 TEMPERATURE (°C) 10 20 30 SUPPLY VOLTAGE (V) 0 100 V1 = 36V 125 10 V1 = 12V 8 6 4 V1 = 5V 2 V1 = 2.
LTC4417 Typical Performance Characteristics 0.5 VVALID(OL) vs Pull-Up Current 1.04 VOV,UV vs Temperature 1.03 0.3 0.2 1.01 V1 1.00 VOV,UV(THR) 0.99 100ms/DIV 0 2.0 0.5 1.0 1.5 PULL-UP CURRENT (mA) 0.
LTC4417 Pin Functions G1, G2, G3: P-Channel MOSFET Gate Drive Outputs. G1, G2 and G3 are used to control external back-to-back Pchannel MOSFETs. When driven low, G1, G2 and G3 are clamped 6V below their corresponding VS1, VS2 and VS3. Connect G1, G2 and G3 to external P-channel MOSFET gate pins. See Dual Channel Applications Section for connecting unused channels. GND: Device Ground. HYS: OV/UV Comparator Hysteresis Input. Connecting HYS to ground sets a fixed 30mV hysteresis for the OV and UV comparators.
LTC4417 Functional Block Diagram VLDO + – 1V VLDO + – 1V VLDO V3 VBEST VLDO D3 V2 BANDGAP UVLO EN VBLDO LDO P1 V1 VBLDO IEN 2µA EN VBESTGEN SHDN P2 P3 P4 LDO PRIORITIZER P5 VLDO SHDN ILIM 5µA 0.24V 0.
LTC4417 Timing Diagram G2 G1 VALID2 VALID1 UV2 UV1 EN SHDN 4417 TD t VALID tpVALID(OFF) tG(SWITCHOVER) tpG(EN,OFF) tpG(EN,ON) tpG(SHDN) 4417f 9
LTC4417 Operation The Functional Block Diagram displays the main functional blocks of this device. The LTC4417 connects one of three power supplies to a common output, VOUT, based on user defined priority. Connection is made by enhancing external back-to-back P-channel MOSFETs. Unlike a diode-OR, which always passes the highest supply voltage to the output, the LTC4417 lets one use a lower voltage supply for primary power and a higher voltage supply as secondary or backup power.
LTC4417 Applications Information Introduction highest valid priority is connected to the common output. If a lower priority input supply is connected to VOUT and a higher priority input supply becomes valid, the LTC4417 disconnects the lower priority supply and connects the higher priority input supply to VOUT. The LTC4417 is an intelligent high voltage triple load switch which automatically connects one of three input supplies to a common output based on predefined pin priorities and validity.
LTC4417 Applications Information Defining Operational Range V1 INPUT SUPPLY To guard against noise and transient voltage events during live insertion, the LTC4417 requires an input supply remain in the OV/UV window for at least 256ms to be valid. The OV/UV window for each input supply is set by a resistive divider (for example, R1, R2 and R3 for V1 input supply) connected from the input supply to GND, as shown in Figure 1.
LTC4417 Applications Information Reduction of the valid operating range can be used to prevent disconnected high impedance input supplies from reconnecting. For example, if 3 series connected AA Alkaline batteries with a total series resistance of 675mΩ is used to source 500mA, the voltage drop due to the series resistance would be 337.5mV. Once the batteries are discharged and are disconnected due to a UV fault, the AA battery stack would recover the 337.5mV drop across the internal series resistance.
LTC4417 Applications Information UV1 pin is pulled below 1V. The LTC4417 then disconnects V1 and connects the next highest valid priority to VOUT. When selecting the external N-channel MOSFET, be sure to account for drain leakage current when setting UV and OV thresholds by adjusting the resistive divider to consume more current. Selecting External P-Channel MOSFETS The LTC4417 drives external back-to-back P-channel MOSFETs to conduct or block load current between an input supply and load.
LTC4417 Applications Information Table 1. List of Suggested P-Channel MOSFETs V1, V2, V3 MOSFET ≤5V Si4465ADY V2 DISCONNECTS MAX RATED VTH(MAX) VGS(MAX) VDS(MAX) RDS(ON) AT 25°C –1V ±8V –8V V2 = 18V VOUT 9mΩ at –4.5V 11mΩ at –2.5V V1 VALIDATES ≤10V Si4931DY* –1V ±8V –12V 18mΩ at –4.5V 22mΩ at –2.5V ≤18V FDS8433A –1V ±8V –20V 47mΩ at –4.5V 70mΩ at –2.5V VOUT V1 = 12V ≤18V IRF7324* –1V ±12V –20V 18mΩ at –4.5V 26mΩ at –2.5V ≤28V Si7135DP –3V ±20V –30V 6.2mΩ at –4.
LTC4417 Applications Information where RS and CS are component values shown in Figure 8. The selection of RS and CL involves an iterative process. Begin by assuming 0.79 • RS • CS = 10µs and choosing CL using Equation (14). See the Inrush Current and Input Voltage Droop section for more details regarding inrush current limiting circuitry, and for selecting RS.
LTC4417 Applications Information P-channel’s gate to source voltage when driving the load and inrush current, CS is the slew rate capacitor and CL is the VOUT hold up capacitance. The output load current IL is neglected for simplicity. Choose CS to be at least ten times the external P-channel MOSFET’s CRSS(MAX), and CVS to be ten times CS.
LTC4417 Applications Information Absolute Maximum Ratings. If the BVDSS of the external P-channel MOSFET is momentarily exceeded, ensure the avalanche energy absorbed by the MOSFETs do not exceed the single pulse avalanche energy specification (EAS). Voltage spikes can be dampened further with a snubber. Input Supply and VOUT Shorts Input shorts can cause high current slew rates.
LTC4417 priority back up input supplies. An internal diode-OR structure selects the highest voltage input supply as the source for VBLDO. If two supplies are similar in voltage and higher than the remaining input supply, the current will be equally divided between the similar voltage supplies. If all input supplies are equal in voltage, the current is divided evenly between them. To limit current consumption from lower priority backup supplies, the LTC4417 prioritizes the internal VLDO’s source supply.
LTC4417 Applications Information Disabling All Channels with EN and SHDN Driving EN below 1V turns off all external back-to-back P-channel MOSFETs but does not interrupt input supply monitoring or reset the 256ms timers. Driving EN above 1V enables the highest valid priority channel. This feature is essential in cascading applications. For applications where EN could be driven below ground, limit the current from EN with a 10k resistor. Forcing SHDN below 0.
LTC4417 Applications Information master and connect its highest valid priority channel to the common output. If seven, or more, input supplies are prioritized, additional LTC4417s can be added by connecting all individual VOUT pins together and connecting each LTC4417’s CAS to the next lower priority LTC4417’s EN. Design Example A 2A multiple input supply system consisting of a 12V supply with a source resistance of 20mΩ, 7.4V main lithium-ion battery, and a backup 7.
LTC4417 Applications Information IRF7324 12V SUPPLY M1 + M2 CS 6.8nF CIN 2700µF 7.4V Li-Ion BATTERY (2 × 3.7V) IRF7324 M3 M4 + 7.4V Li-Ion BATTERY (2 × 3.7V) DS BAT54 RS 2.21k M5 + CVS1 68nF CV3 0.1µF CV2 0.1µF CV1 0.1µF VS1 R3 806k R2 41.2k R1 60.4k R6 768k G1 CVS3 0.1µF VS2 G2 + VS3 V1 140k R4 113k OV1 VALID1 VALID2 VALID3 140k R7 113k CL 100µF VOUT R10 1M UV1 R11 1M R12 1M V1 INVALID V2 INVALID V3 INVALID LTC4417 UV2 OV2 V3 R8 53.6k G3 VOUT V2 R5 53.
LTC4417 Applications Information Significant power is dissipated during the channel transition time. The SOA of the P-channel MOSFET should be checked to make sure their SOA is not violated. Worst case slew rate limited channel transition time would occur when the lithium-ion batteries are running low at 5.6V, and the supply connects while running 20% high, at 14.4V. This results in a time of 25µs, as shown in Equation (24). (14.4V – 5.
LTC4417 Applications Information Because this is a single resistive string R2, R3, and IOV_UV(HYS) sets the hysteresis voltage with Equation (30) OVHYS = (R2 + R3) • IOVUV(HYS) = (33) (41.2kΩ + 806kΩ) • 247nA = 209mV This results in an OV threshold of 15.0V and UV threshold of 8.9V. With hysteresis, the OVHYS threshold is 14.8V and the UVHYS threshold is 9.1V. For the desired OV and UV 6% accuracy, 1% resistors used in this example are acceptable.
LTC4417 Typical Applications 12V System Using Swappable and Backup Batteries 12V WALL ADAPTER + M1 IRF7324 M2 CIN1 2200µF 12V NiCd BATTERY IRF7324 M3 + M4 CS 6.8nF RS 2.21k DS BAT54 11.1V Li-Ion BATTERY (3 × 3.7V) M5 + CVS1 0.1µF CV3 0.1µF CV2 0.1µF CV1 0.1µF R3 1.02M R2 48.7k R1 76.8k R6 1.02M R5 36.5k R4 76.8k R9 1.0M R8 40.2k R7 90.9k + VS2 G2 V1 VS3 G3 VOUT VOUT R10 1M UV1 OV1 VALID1 VALID2 VALID3 V2 UV2 CL 100µF CVS3 0.
LTC4417 Typical Applications 18V System with Reverse Voltage Protection 18V WALL ADAPTER FDS4685 M1 FDS4685 M2 CIN1 2200µF D1 SMBJ26CA D4 SMBJ26A CVS1 0.1µF 11.1V Li-Ion BATTERY + VOUT FDS4685 M3 FDS4685 M4 D2 SMBJ26CA CVS2 0.1µF 12V LEAD-ACID BATTERY + FDS4685 M5 FDS4685 M6 CL 100µF D3 SMBJ26CA CVS3 0.1µF CV1 0.1µF VS1 CV3 0.1µF CV2 0.1µF R3 1.02M R2 11.8k R1 54.9k R6 768k R5 90.9k R4 75k R9 698k R8 16.9k R7 49.
CV2 35V TANTALUM CV1 470µF 12V SYSTEM SUPPLY + R7 41.2k R8 1.02M R4 33.2k R5 127k R6 806k R1 66.5k R2 15.8k R3 806k VS1 OV3 UV3 V3 OV2 UV2 V2 OV1 UV1 V1 CVS1 1µF FDS4685 M1 DS BAT54 G1 GND LTC4417 VS2 CVS2 0.1µF G2 FDS4685 M4 CS 6.8nF FDS4685 M3 RS 1.43k FDS4685 M2 VOUT G3 4417 TA04 EN SHDN HYS CAS VALID3 VALID2 VALID1 VS3 L1A 33µH C11 10µF C10 10µF R23 1Ω R22 25k R21 536k C8 10nF C7 4.
LTC4417 Typical Applications Selecting from USB, FireWire, and Li-Ion Battery Power Sources 4.35V TO 5.25V USB 8V TO 30V FireWire IEEE1394 FDS4685 FDS4685 M1 M2 VOUT CL 47µF CIN1 10µF FDS4685 M3 FDS4685 M4 CIN2 22µF CS 6.8nF CVS1 0.1µF CVS2 1µF 7.4V Li-Ion BATTERY RS 1k DS BAT54 + CV1 0.1µF CV2 0.1µF R2 24.9k CV3 0.1µF R1 75k R6 576k R5 78.7k R4 20.5k R9 931k R8 63.4k R7 137k FDS4685 M6 CVS3 0.
LTC4417 Typical Applications Wall Adapter and USB Input with Battery Backup 5V WALL ADAPTER + Si4931DY M1 M2 + CIN1 1000µF 4.35V TO 5.25V USB VOUT CL 47µF Si4931DY M3 M4 CIN2 10µF CV1 0.1µF 4 × AA BATTERY Si4931DY M5 M6 + CVS1 0.1µF CV2 0.1µF VS1 R3 412k R2 37.4k CV3 0.1µF R1 95.3k R4 412k R5 33.2k R6 100k R9 432k R11 562k R8 80.6k R7 86.6k CVS2 0.1µF R10 52.3k G1 CVS3 0.
LTC4417 Package Description Please refer to http://www.linear.com/designtools/packaging/ for the most recent package drawings. GN Package 24-Lead Plastic SSOP (Narrow .150 Inch) (Reference LTC DWG # 05-08-1641 Rev B) .337 – .344* (8.560 – 8.738) 24 23 22 21 20 19 18 17 16 15 1413 .045 ±.005 .229 – .244 (5.817 – 6.198) .254 MIN .033 (0.838) REF .150 – .157** (3.810 – 3.988) .150 – .165 1 .0165 ±.0015 2 3 4 5 6 7 8 9 10 11 12 .0250 BSC RECOMMENDED SOLDER PAD LAYOUT .015 ±.004 × 45° (0.38 ±0.
LTC4417 Package Description Please refer to http://www.linear.com/designtools/packaging/ for the most recent package drawings. UF Package 24-Lead Plastic QFN (4mm × 4mm) (Reference LTC DWG # 05-08-1697 Rev B) 0.70 ±0.05 4.50 ±0.05 2.45 ±0.05 3.10 ±0.05 (4 SIDES) PACKAGE OUTLINE 0.25 ±0.05 0.50 BSC RECOMMENDED SOLDER PAD PITCH AND DIMENSIONS 4.00 ±0.10 (4 SIDES) BOTTOM VIEW—EXPOSED PAD R = 0.115 TYP 0.75 ±0.05 PIN 1 NOTCH R = 0.20 TYP OR 0.35 × 45° CHAMFER 23 24 PIN 1 TOP MARK (NOTE 6) 0.40 ±0.
LTC4417 Typical Application Dual Channel LTC4417 Application with Output Voltage Monitoring Using Third Channel 12V WALL ADAPTER + IRF7324 M1 + CIN 2200µF IRF7324 M3 + CV2 0.1µF CV1 0.1µF R3 806k R2 39.2k R1 60.4k R6 845k R5 26.1k R4 51.1k CVS2 1µF VS1 G1 DS BAT54 VS2 C1 10nF OV1 GND R10 1M R11 1M R12 1M VALID1 V1 INVALID VALID2 V2 INVALID VALID3 5V OUTPUT INVALID V2 LTC4417 UV2 OV2 EN SHDN HYS CAS OV3 R7 84.5k SHDN 5V OUTPUT G3 VOUT UV3 R8 15.
