Datasheet

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LTC4365

4365fa

For more information www.linear.com/LTC4365

Typical applicaTion

FeaTures DescripTion

Overvoltage,

Undervoltage and Reverse

Supply Protection Controller

12V Automotive Application

applicaTions

Wide Operating Voltage Range: 2.5V to 34V

Overvoltage Protection to 60V

Reverse Supply Protection to –40V

LTC4365: Blocks 50Hz and 60Hz AC Power

LTC4365-1: Fast (1ms) Recovery from Fault

No Input Capacitor or TVS Required for Most

Applications

Adjustable Undervoltage and Overvoltage

Protection Range

Charge Pump Enhances External N-Channel MOSFET

Low Operating Current: 125µA

Low Shutdown Current: 10µA

Compact 8-Lead, 3mm × 2mm DFN and

TSOT-23 (ThinSOT™) Packages

Portable Instrumentation

Industrial Automation

Laptops

Automotive Surge Protection

L, LT , LT C , LT M , Linear Technology and the Linear logo are registered trademarks and

ThinSOT and Hot Swap are trademarks of Linear Technology Corporation. All other trademarks

are the property of their respective owners.

Load Protected from Reverse and Overvoltage at V

The LTC

4365 protects applications where power supply

input voltages may be too high, too low or even negative.

It does this by controlling the gate voltages of a pair of

external N-channel MOSFETs to ensure that the output

stays within a safe operating range.The LTC4365 can

withstand voltages between –40V and 60V and has an

operating range of 2.5V to 34V, while consuming only

125µA in normal operation.

Tw o comparator inputs allow configuration of the over

voltage (OV) and undervoltage (UV) set points using an

external resistive divider. A shutdown pin provides external

control for enabling and disabling the MOSFETs as well

as placing the device in a low current shutdown state. A

fault output provides status of the gate pin pulling low. A

fault is indicated when the part is in shutdown or the input

voltage is outside the UV and OV set points.

The LTC4365 has a 36ms turn-on delay that

debounces

live

connections and blocks 50Hz to 60Hz AC power. For

fast recovery after faults, the LTC4365-1 has a reduced

1ms turn-on delay.

–30V

GND

10V/DIV

30V

4365 TA01b

1s/DIV

UV = 3.5V

OV = 18V

OUT

VALID

WINDOW

SHDN

OV = 18V

UV = 3.5V

4365 TA01a

OUT

FAULT

GATE

12V

OUT

Si4946

GND

LTC4365

510k

1820k

243k

59k

Summary of content (20 pages)

PAGE 1
LTC4365 Overvoltage, Undervoltage and Reverse Supply Protection Controller Description Features n n n n n n n n n n n Wide Operating Voltage Range: 2.
PAGE 2
LTC4365 Absolute Maximum Ratings Supply Voltage (Note 1) VIN........................................................... –40V to 60V Input Voltages (Note 3) UV, SHDN............................................... –0.3V to 60V OV............................................................. –0.3V to 6V VOUT....................................................... –0.3V to 40V Output Voltages (Note 4) FAULT...................................................... –0.3V to 60V GATE....................................
PAGE 3
LTC4365 Order Information Lead Free Finish TAPE AND REEL (MINI) TAPE AND REEL PART MARKING* PACKAGE DESCRIPTION TEMPERATURE RANGE LTC4365CDDB#TRMPBF LTC4365CDDB#TRPBF LFKS 8-Lead (3mm × 2mm) Plastic DFN 0°C to 70°C LTC4365CDDB-1#TRMPBF LTC4365CDDB-1#TRPBF LGMB 8-Lead (3mm × 2mm) Plastic DFN 0°C to 70°C LTC4365IDDB#TRMPBF LTC4365IDDB#TRPBF LFKS 8-Lead (3mm × 2mm) Plastic DFN –40°C to 85°C LTC4365IDDB-1#TRMPBF LTC4365IDDB-1#TRPBF LGMB 8-Lead (3mm × 2mm) Plastic DFN –40°C to 85°C LTC43
PAGE 4
LTC4365 Electrical Characteristics The l denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25°C. VIN = 2.5V to 34V, unless otherwise noted. (Note 2) SYMBOL PARAMETER CONDITIONS tRECOVERY GATE Recovery Delay Time VIN = 12V, Power Good to ΔVGATE > 0V LTC4365, CGATE = 2.2nF LTC4365-1, CGATE = 2.2nF MIN TYP MAX UNITS l l 26 0.6 36 1 49 1.5 ms ms UV, OV VUV UV Input Threshold Voltage UV Falling → ΔVGATE = 0V l 492.
PAGE 5
LTC4365 Typical Performance Characteristics VIN Operating Current vs Temperature VIN Shutdown Current vs VIN 30 100 SHDN = 2.5V VOUT = VIN 80 VIN Current vs VIN (–40 to 60V) 400 VIN = VOUT SHDN = 0V 25 SHDN = UV = 0V 0 125°C VIN = 34V 70°C 15 IVIN (µA) VIN = 12V 40 IVIN (µA) IVIN (µA) 20 60 25°C –45°C –400 –800 125°C 10 20 VIN = 2.5V 0 –50 –25 –45°C 5 75 0 50 25 TEMPERATURE (°C) 100 0 125 5 0 10 15 20 VIN (V) –1200 25 30 –1600 –50 200 SHDN = 2.
PAGE 6
LTC4365 Typical Performance Characteristics OV Threshold vs Temperature UV Threshold vs Temperature 507.5 507.5 VIN = VOUT = 12V 505.0 505.0 502.5 502.5 UV/OV Leakage vs Temperature 1.00 VIN = VOUT = 12V VUV/OV = 0.5V VIN = 12V 500.0 ILEAK (nA) VOV (mV) VUV (mV) 0.75 500.0 497.5 497.5 495.0 495.0 492.5 –50 492.5 –50 0.50 0.25 OV 75 0 50 25 TEMPERATURE (°C) 100 125 –25 75 0 50 25 TEMPERATURE (°C) 50 tRECOVERY (ms) tFAULT (µs) 50 40 12 8 4 VIN = 12V 30 20 VIN = 2.
PAGE 7
LTC4365 Pin Functions Exposed Pad: Connect to device ground. FAULT: Fault Indication Output. This high voltage open drain output is pulled low if UV is below its monitor threshold, if OV is above its monitor threshold, if SHDN is low, or if VIN has not risen above VIN(UVLO). GATE: Gate Drive Output for External N-channel MOSFETs. An internal charge pump provides 20µA of pull-up current and up to 9.8V of enhancement to the gate of an external N-channel MOSFET.
PAGE 8
LTC4365 Block Diagram REVERSE PROTECTION VIN –40V TO 60V GATE – + CLOSES SWITCH WHEN VIN IS NEGATIVE 5V INTERNAL SUPPLY LDO 6.5V INTERNAL SUPPLY VOUT ENABLE 2.2V UVLO UV SHDN GATE CHARGE PUMP f = 400kHz DELAY TIMERS + + FAULT OFF TURN OFF SHDN LOGIC – OV IGATE 50mA 25mV HYSTERESIS 90µA FAULT GATE PULLDOWN – 0.5V GND 4365 BD Operation Many of today’s electronic systems get their power from external sources such as wall wart adapters, batteries and custom power supplies.
PAGE 9
LTC4365 Operation the system only if the input supply meets the user selectable voltage window. Reverse supply protection circuits automatically isolate the load from negative input voltages. During normal operation, a high voltage charge pump enhances the gate of external N-channel power MOSFETs. Power consumption is 10µA during shutdown and 125µA while operating. The LTC4365 integrates all these functions in tiny TSOT-23 and 3mm × 2mm DFN packages.
PAGE 10
LTC4365 Applications Information Figure 3 highlights the dependence of the gate drive on VIN and VOUT. When system power is first turned on (SHDN low to high, VOUT = 0V), gate drive is at a maximum for all values of VIN. This helps prevent start-up problems into heavy loads by ensuring that there is enough gate drive to support the load. As VOUT ramps up from 0V, the absolute value of the GATE voltage remains fixed until VOUT is greater than the lower of (VIN –1V) or 6V.
PAGE 11
LTC4365 Applications Information Figure 5 shows the timing associated with the UV pin. Once a UV fault propagates through the UV comparator (tFAULT), the FAULT output is asserted low and a 50mA current sink discharges the GATE pin. As VOUT falls, the GATE pin tracks VOUT. UV VUV tFAULT FAULT tGATE(FAST) The following 3-step procedure helps select the resistor values for the resistive divider of Figure 4. This procedure minimizes UV and OV offset errors caused by leakage currents at the respective pins.
PAGE 12
LTC4365 Applications Information As shown in Figure 7, external back-to-back N-channel MOSFETs are required for reverse supply protection. When VIN goes negative, the reverse VIN comparator closes the internal switch, which in turn connects the gates of the external MOSFETs to the negative VIN voltage. The body diode (D1) of M1 turns on, but the body diode (D2) of M2 remains in reverse blocking mode. This means that the common source connection of M1 and M2 remains about a diode drop higher than VIN.
PAGE 13
LTC4365 Applications Information Recovery Timer The LTC4365 has a recovery delay timer that filters noise at VIN and helps prevent chatter at VOUT. After either an OV or UV fault has occurred, the input supply must return to the desired operating voltage window for at least 36ms (tRECOVERY) in order to turn the external MOSFET back on as illustrated in Figure 5 and Figure 6. For applications that require faster turn-on after a fault, the LTC4365-1 provides a 1ms recovery timeout period.
PAGE 14
LTC4365 Applications Information the two supplies, thus turning off the external back-to-back MOSFETs. The application of Figure 12 uses two LTC4365s to select between two power supplies. Care should be taken to ensure that only one of the two LTC4365s is enabled at any given time. V1 M1 GATE VOUT LTC4365 OUT SHDN Since the MOSFET acts like a source follower, the slew rate at VOUT equals the slew rate at GATE.
PAGE 15
LTC4365 Applications Information Transients During OV Fault pacitance at the VIN node. D1 is an optional power clamp (TVS, Tranzorb) recommended for applications where the DC input voltage can exceed 24V and with large VIN parasitic inductance. No clamp was used to capture the waveforms of Figure 16. In order to maintain reverse supply protection, D1 must be a bi-directional clamp rated for at least 225W peak pulse power dissipation.
PAGE 16
LTC4365 Applications Information Regulator Applications and duty cycle of the VIN glitch must not exceed the SOA rating of the external MOSFETs. Hysteretic Regulator Solar Charger Built-in hysteresis and the availability of both inverting and noninverting control inputs (OV and UV) facilitate the design of hysteretic regulators. Figure 17 shows how the LTC4365-1 can protect a load from OV transients, while regulating the output voltage at a user-defined level.
PAGE 17
LTC4365 Applications Information Note that during initial start-up, the LTC4365-1 will not turn on the external MOSFETs until a battery is first connected to the VIN pin. To begin operation, VIN must initially rise above the 2.2V UVLO lockout voltage. Connecting the battery ensures that the LTC4365-1 comes out of UVLO. handling capability, drain and gate breakdown voltages, and threshold voltage. The drain to source breakdown voltage must be higher than the maximum voltage expected between VIN and VOUT.
PAGE 18
LTC4365 Package Description Please refer to http://www.linear.com/designtools/packaging/ for the most recent package drawings. TS8 Package 8-Lead Plastic TSOT-23 (Reference LTC DWG # 05-08-1637 Rev A) 0.40 MAX 2.90 BSC (NOTE 4) 0.65 REF 1.22 REF 1.4 MIN 3.85 MAX 2.62 REF 2.80 BSC 1.50 – 1.75 (NOTE 4) PIN ONE ID RECOMMENDED SOLDER PAD LAYOUT PER IPC CALCULATOR 0.22 – 0.36 8 PLCS (NOTE 3) 0.65 BSC 0.80 – 0.90 0.20 BSC 0.01 – 0.10 1.00 MAX DATUM ‘A’ 0.30 – 0.50 REF 1.95 BSC 0.09 – 0.
PAGE 19
LTC4365 Revision History REV DATE DESCRIPTION A 09/13 Added LTC4365-1 Information PAGE NUMBER Multiple Operation section: Rewritten with new Figure 1 8, 9 Table 1: MOSFET for ≤30V changed to Si4214 from Si4230 10 Figure 13: Inserted R5, 100k resistor to SHDN pin Added "Regulator Applications" with three subsections and Figures 17 to 20 Updated Typical Application 14 16, 17 20 4365fa Information furnished by Linear Technology Corporation is believed to be accurate and reliable.
PAGE 20
LTC4365 Typical Application LTC4365 Protects Step Down Regulator from –30V to 30V VIN Faults Si4214 30V DUAL N-CHANNEL VIN 12V NOMINAL VOUT OUTPUT 5V 3.5A 10µF VOUT PROTECTED FROM –30V TO 30V VIN BD RUN/SS BOOST GATE VIN VOUT 15k LTC4365 510k 680pF SHDN 1820k UV FAULT 63.4k 243k OV GND 59k LT1913 VC 0.47µF 4.7µH SW RT PG FB SYNC GND 536k 100k 47µF OV = 18V UV = 3.