LTC4231HUD-1#PBF - ANALOG DEVICES

LTC4231

Rev. B

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TYPICAL APPLICATION

FEATURES DESCRIPTION

Micropower Hot Swap

Controller

The LT C

4231 is a micropower Hot Swap controller that

allows safe circuit board insertion and removal from a live

power supply. An internal high side switch driver controls

the gate of an external N-channel MOSFET. Back-to-back

MOSFETs can be used for reverse supply protection down

to –40V.

The LTC4231 provides a debounce delay and allows the

GATE to be ramped up at an adjustable rate. After start-

up, the LTC4231's quiescent current drops to 4µA during

normal operation with output active. UVL, UVH, OV and

GNDSW monitor overvoltage and undervoltage periodi-

cally, keeping total quiescent current low. Pulling SHDN

low shuts down the LTC4231 and quiescent current drops

to 0.3µA.

During an overcurrent fault, the LTC4231 actively limits

current while running an adjustable timer. The LTC4231-1

remains off after a current fault while the LTC4231-2 auto

matically reapplies power after a cool-down period.

Battery Hot Swap with Reverse Protection

APPLICATIONS

n Enables Safe Board Insertion and Removal from a

Power Supply

n 4µA Supply Current

n 0.3µA Shutdown Current

n Wide Operating Voltage Range: 2.7V to 36V

n Reverse Supply Protection to –40V

n Adjustable Analog Current Limit with Circuit Breaker

n Automatic Retry or Latchoff on Current Fault

n Overvoltage and Undervoltage Monitoring

n Controls Single or Back-to-Back N-Channel MOSFETs

n 12-Lead MSOP and 3mm × 3mm QFN Packages

n AEC-Q100 Qualified for Automotive Applications

n Battery Powered Equipment

n Solar Powered Systems

n Portable Instruments

n Automotive Battery Protection

n Energy Harvesting

SENSE GATE

UVL

UVH

GNDSW

SOURCE

STATUS

SHDN

TIMER

LTC4231

Si7164DP

SMAJ24CA 22.5mΩ Si5410DU

GND

20k

220µF

VOUT

24V

1020k

1.65k

24V

4.22k

32.4k

180nF

4231 TA01a

GATE

20V/DIV

SOURCE

20V/DIV

ILOAD

5A/DIV

10ms/DIV 4231 TA01b

CONTACT

BOUNCE

Power-Up Waveforms

All registered trademarks and trademarks are the property of their respective owners.

LTC4231

Rev. B

For more information www.analog.com

ABSOLUTE MAXIMUM RATINGS

Supply Voltage

IN ............................................................ –40V to 40V

Input Voltages

SENSE, SOURCE ..................................... –40V to 40V

IN–SENSE ............................................... –40V to 40V

SHDN, UVL, UVH, OV, GNDSW .............. –0.3V to 40V

Input Currents

SHDN, UVL, UVH, OV, GNDSW (Note 3) ............–1mA

Output Voltages

GATE–SOURCE (Note 4) .........................–0.3V to 13V

(Notes 1, 2)

ORDER INFORMATION

LEAD FREE FINISH TAPE AND REEL PART MARKING* PACKAGE DESCRIPTION TEMPERATURE RANGE

LTC4231CUD-1#PBF LTC4231CUD-1#TRPBF LGMX 12-Lead (3mm × 3mm) Plastic QFN 0°C to 70°C

LTC4231CUD-2#PBF LTC4231CUD-2#TRPBF LGSP 12-Lead (3mm × 3mm) Plastic QFN 0°C to 70°C

LTC4231IUD-1#PBF LTC4231IUD-1#TRPBF LGMX 12-Lead (3mm × 3mm) Plastic QFN –40°C to 85°C

LTC4231IUD-2#PBF LTC4231IUD-2#TRPBF LGSP 12-Lead (3mm × 3mm) Plastic QFN –40°C to 85°C

LTC4231HUD-1#PBF LTC4231HUD-1#TRPBF LGMX 12-Lead (3mm × 3mm) Plastic QFN –40°C to 125°C

LTC4231HUD-2#PBF LTC4231HUD-2#TRPBF LGSP 12-Lead (3mm × 3mm) Plastic QFN –40°C to 125°C

LTC4231CMS-1#PBF LTC4231CMS-1#TRPBF 42311 12-Lead Plastic MSOP 0°C to 70°C

LTC4231CMS-2#PBF LTC4231CMS-2#TRPBF 42312 12-Lead Plastic MSOP 0°C to 70°C

LTC4231IMS-1#PBF LTC4231IMS-1#TRPBF 42311 12-Lead Plastic MSOP –40°C to 85°C

LTC4231IMS-2#PBF LTC4231IMS-2#TRPBF 42312 12-Lead Plastic MSOP –40°C to 85°C

LTC4231HMS-1#PBF LTC4231HMS-1#TRPBF 42311 12-Lead Plastic MSOP –40°C to 125°C

LTC4231HMS-2#PBF LTC4231HMS-2#TRPBF 42312 12-Lead Plastic MSOP –40°C to 125°C

12 11 10

456

TOP VIEW

UD PACKAGE

12-LEAD (3mm × 3mm) PLASTIC QFN

1SHDN

UVL

UVH

SOURCE

TIMER

STATUS

SENSE

GATE

GNDSW

GND

TJMAX = 150°C, θJA = 68°C/W

EXPOSED PAD (PIN 13) PCB CONNECTION TO GND IS OPTIONAL

SENSE

SHDN

UVL

UVH

GATE

SOURCE

TIMER

STATUS

GND

GNDSW

TOP VIEW

MS PACKAGE

12-LEAD PLASTIC MSOP

TJMAX = 150°C, θJA = 135°C/W

PIN CONFIGURATION

GATE–SENSE .......................................... –40V to 20V

STATUS ................................................. –0.3V to 40V

TIMER ...................................................... –0.3V to 4V

Operating Ambient Temperature Range

LTC4231C ................................................ 0°C to 70°C

LTC4231I..............................................–40°C to 85°C

LTC4231H .......................................... –40°C to 125°C

Storage Temperature Range .................. –65°C to 150°C

Lead Temperature (Soldering, 10 sec)

MSOP Package ................................................. 300°C

LTC4231

Rev. B

For more information www.analog.com

ORDER INFORMATION

ELECTRICAL CHARACTERISTICS

The l denotes the specifications which apply over the full operating

temperature range, otherwise specifications are at TA = 25°C. IN = 12V, unless otherwise noted.

SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS

VIN Input Supply Voltage Range l2.7 36 V

VIN(UVL) Input Supply Undervoltage Lockout IN Rising l2 2.3 2.6 V

∆VIN(HYST) Input Supply Undervoltage Lockout

Hysteresis

200

ICC Supply Current (Average)

Normal On, Voltage or Current Fault

Start-Up or Overcurrent

Shutdown

Reverse Input

(Note 5)

IGATE ≤ –0.1µA, CGATE-SOURCE = 1nF, (C-Grade, I-Grade)

(H-Grade)

SHDN Low, GATE Pulled to GND, (C-Grade, I-Grade)

(H-Grade)

IN, SENSE = –40V

300

0.3

–2.5

600

–5

µA

SENSE

∆VSENSE(CB) Circuit Breaker Threshold (VIN – VSENSE)l47 50 53 mV

∆VSENSE(ACL) Analog Current Limit During Output Short-Circuit l65 80 90 mV

ISENSE SENSE Input Current SHDN = High, SENSE = 12V l0.3 1 µA

GATE, SOURCE

∆VGATE External N-Channel Gate Drive

(VGATE – VSOURCE)

VIN < 7V, IGATE = 0, –0.1µA

VIN ≥ 7V, IGATE = 0, –0.1µA

4.5

6.2

11.4

∆VGATE(H) ∆VGATE (VGATE – VSOURCE) Threshold

That Deactivates the Charge Pump

VIN < 7V

VIN ≥ 7V

5.5

6.5

11.7

VGATE(L) GATE Low Threshold To Enter Shutdown or Voltage Fault l0.4 1.2 1.8 V

IGATE(UP) GATE Pull-Up Current GATE On, GATE = 1V l–7 –10 –13 µA

IGATE(FAST) GATE Fast Pull-Down Current ∆VSENSE = 0.5V, ∆VGATE = 5V l 70 130 mA

IGATE(SLOW) GATE Slow Pull-Down Current SHDN = 0V, ∆VGATE = 5V l0.6 1 mA

tD(ON) Turn-On Debounce Delay UVL = UVH = 2V, OV = 0V, SHDN = Step 0V to 5V l20 40 60 ms

tRETRY Auto-Retry Delay LTC4231-2 l0.27 0.5 0.73 s

tPHL(ILIM) Overcurrent to GATE Low Propagation

Delay

∆VSENSE = Step 0mV to 300mV,

CGATE = 1nF, ∆VGATE Crosses 1V

l 0.5 1 µs

LEAD FREE FINISH TAPE AND REEL PART MARKING* PACKAGE DESCRIPTION TEMPERATURE RANGE

AUTOMOTIVE PRODUCTS**

LTC4231IMS-1#WPBF LTC4231IMS-1#WTRPBF 42311 12-Lead Plastic MSOP –40°C to 85°C

LTC4231IMS-2#WPBF LTC4231IMS-2#WTRPBF 42312 12-Lead Plastic MSOP –40°C to 85°C

LTC4231HMS-1#WPBF LTC4231HMS-1#WTRPBF 42311 12-Lead Plastic MSOP –40°C to 125°C

LTC4231HMS-2#WPBF LTC4231HMS-2#WTRPBF 42312 12-Lead Plastic MSOP –40°C to 125°C

Contact the factory for parts specified with wider operating temperature ranges. *The temperature grade is identified by a label on the shipping container.

Tape and reel specifications. Some packages are available in 500 unit reels through designated sales channels with #TRMPBF suffix.

**Versions of this part are available with controlled manufacturing to support the quality and reliability requirements of automotive applications. These

models are designated with a #W suffix. Only the automotive grade products shown are available for use in automotive applications. Contact your

local Analog Devices account representative for specific product ordering information and to obtain the specific Automotive Reliability reports for

thesemodels.

LTC4231

Rev. B

For more information www.analog.com

ELECTRICAL CHARACTERISTICS

The l denotes the specifications which apply over the full operating

temperature range, otherwise specifications are at TA = 25°C. IN = 12V, unless otherwise noted.

SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS

UVL, UVH, OV, GNDSW, STATUS and SHDN

VUV UVL, UVH Threshold l0.776 0.795 0.814 V

VOV OV Threshold OV Rising l0.776 0.795 0.814 V

VOV(HYST) OV Hysteresis l3 15 30 mV

ILEAK(0.9V) UVL, UVH and OV Leakage Current V = 0.9V (C-Grade, I-Grade)

(H-Grade)

±10

±100

ILEAK(12V) UVL, UVH, OV, GNDSW, STATUS and

SHDN Leakage Current

V = 12V (C-Grade, I-Grade)

(H-Grade)

±100

±500

RON(GNDSW) Switch Resistance l80 200 Ω

VOL STATUS Output Low Voltage I = 2mA l0.2 0.4 V

VSHDN SHDN Input Threshold l0.4 0.8 1.5 V

tPERIOD Sampling Period l5 10 15 ms

tSAMPLE Sampling Width l100 200 300 µs

TIMER

tCB Circuit Breaker Delay CT = 100nF l1.7 2.4 3.5 ms

VTIMER(H) TIMER High Threshold TIMER Rising l1.170 1.193 1.216 V

VTIMER(L) TIMER Low Threshold TIMER Falling l0.07 0.1 0.13 V

ITIMER(UP) TIMER Pull-Up Current TIMER = 0.5V, Circuit Breaker Tripped l–35 –50 –65 µA

ITIMER(DN) TIMER Pull-Down Current TIMER = 0.5V, Circuit Breaker Recovery l3 5 7 µA

Note 1: Stresses beyond those listed under Absolute Maximum Ratings

may cause permanent damage to the device. Exposure to any Absolute

Maximum Rating condition for extended periods may affect device

reliability and lifetime.

Note 2: All currents into device pins are positive; all currents out of device

pins are negative. All voltages are referenced to GND unless otherwise

specified.

Note 3: These pins can be tied to voltages below –0.3V through a

resistance that limits the current below 1mA.

Note 4: An internal clamp limits GATE to a minimum of 13V above

SOURCE. Driving this pin to voltages beyond this clamp may damage the

device.

Note 5: For modes where GATE is pulled to GND, ICC = IIN + ISENSE.

Else ICC = IIN + ISENSE + ISOURCE.

LTC4231

Rev. B

For more information www.analog.com

Average Supply Current vs IN

Average Supply Current

(Normal On) vs GATE Leakage

Average Supply Current

vs Temperature

TYPICAL PERFORMANCE CHARACTERISTICS

VIN (V)

ICC (µA)

10 20 30

4231 G01

NORMAL ON

IGATE = –0.1µA

SHUTDOWN

IGATE (µA)

–0.01

ICC (µA)

100

1000

–0.1 –1 –10

4231 G02

–100

VIN = 12V

TEMPERATURE (°C)

–50

0.1

ICC (µA)

100

–25 0 25 50 75 125100

4231 G03

150

VIN = 12V

NORMAL ON

IGATE = –1µA

NORMAL ON

IGATE = –0.1µA

NORMAL ON

IGATE = 0

SHUTDOWN

Supply Current (Reverse Input)

vs IN ∆VGATE (Average) vs IN

∆VGATE (Average)

vs GATE Leakage

VIN (V)

ICC (mA)

–1

–2

–3

–10 –30–20

4231 G04

–40

VIN (V)

IGATE = –0.1µA

∆VGATE (V)

10 3020

4231 G05

IGATE (µA)

VIN = 12V

VIN = 2.7V

∆VGATE (V)

–6 –10–8–2 –4

4231 G06

–12

LTC4231

Rev. B

For more information www.analog.com

TYPICAL PERFORMANCE CHARACTERISTICS

GATE Pull-Up Current vs VGATE

Overcurrent to GATE Low

Propagation Delay

UVL, UVH, OV Thresholds

vs Temperature

GNDSW Switch Resistance

vs IN

STATUS Output Low Voltage

vs Current

STATUS Output Low Voltage

vs Temperature

VGATE (V)

VIN = 12V

IGATE(UP) (µA)

–5

–10

–15

–20

15 205 10

4231 G07

VIN – VSENSE (mV)

CGATE = 1nF

CTIMER = 82nF

0.1

OVERCURRENT TO GATE LOW

PROPAGATION DELAY (µs)

100

1000

200 350100 150 300250

4231 G08

400

TEMPERATURE (°C)

VIN = 12V

UVL HIGH TO LOW

UVH LOW TO HIGH

OV LOW TO HIGH

OV HIGH TO LOW

–50

0.770

THRESHOLD (V)

0.775

0.780

0.785

0.790

0.795

0.800

10075 12525 50–25 0

4231 G09

150

VIN (V)

RON(GNDSW) (Ω)

100

110

20 3010

4231 G10

ISTATUS (mA)

VIN = 12V

VSTATUS (mV)

100

200

300

400

500

600

4321

4231 G11

TEMPERATURE (°C)

VIN = 12V

ISTATUS = 2mA

–50

VSTATUS (mV)

100

200

300

400

10075 12525 50–25 0

4231 G12

150

LTC4231

Rev. B

For more information www.analog.com

PIN FUNCTIONS

GATE: Gate Drive for External N-Channel MOSFET. After

all start-up conditions are satisfied, a 10μA pull-up cur-

rent from the internal charge pump charges up ∆VGATE to

the high threshold voltage ∆VGATE(H) and then turns off.

The charge pump turns on again when ∆VGATE decays by

more than 0.7V or every 15ms, whichever comes first,

and recharges ∆V

GATE

to ∆V

GATE(H)

. During GATE turn-

off, a 1mA pull-down current discharges GATE to GND.

During severe short circuits, a 130mA pull-down current

is activated to discharge GATE to SOURCE.

GND: Device Ground.

GNDSW: Switched GND. Connect this pin to an external

resistive network to monitor IN for overvoltage or under-

voltage (OV/UV). To reduce the power dissipated by this

resistive divider, the LTC4231 periodically samples IN by

connecting GNDSW to GND once every 10ms. Tie this pin

to GND if unused.

IN: Supply Voltage and Current Sense Input. This pin has

a nominal undervoltage lockout threshold of 2.3V.

SHDN: Shutdown Control Input. A logic high at SHDN

enables the LTC4231. GATE ramps up after a debounce

delay of 40ms. A logic low at SHDN activates a 1mA pull-

down current at GATE, discharging it to GND. Once GATE

< 1.2V, the LTC4231 enters a low current Shutdown.

Connect to IN if unused. When connected to IN, if IN goes

below ground, use a resistor to limit the current to ≤1mA.

OV: Overvoltage Comparator Input. Connect this pin to an

external resistive network to monitor IN for OV. This pin

connects internally to an overvoltage comparator with a

0.795V threshold. To reduce the power dissipated by this

resistive divider, the LTC4231 periodically samples IN by

connecting GNDSW to GND once every 10ms. Once an

OV is detected at IN, GATE and STATUS pull low. Tie this

pin to GND if unused.

SENSE: Current Sense Input. Connect to the output of

the current sense resistor. The circuit breaker comparator

and the analog current limit amplifier monitor the voltage

across the current sense resistor. During an overcurrent

fault when ∆V

SENSE

exceeds 50mV, the circuit breaker

comparator trips and triggers TIMER to ramp up. For

more severe overcurrent faults, the analog current limit

amplifier controls the gate of the external MOSFET to keep

∆V

SENSE

at 80mV. To disable the circuit breaker compara-

tor and analog current limit amplifier, connect this pin to

IN.

SOURCE: N-Channel MOSFET Source Connection.

Connect this pin to the source of the external MOSFET.

STATUS: Status Output. Open-drain output that goes high

impedance when ∆V

GATE

first exceeds ∆V

GATE(H)

. The state

of the pin is latched and resets (pulls low) when SHDN

goes low, an UVLO occurs, an OV/UV is detected at IN or

an overcurrent fault sets the internal current fault latch.

This pin may be left open if unused.

TIMER: Timer Input. Connect a capacitor between this

pin and GND to set a 24ms/µF duration for overcurrent

before the internal current fault latch trips and turns off the

MOSFET. For the LTC4231-1 latchoff option, the MOSFET

remains off until the current fault latch is cleared by pull-

ing SHDN low or by cycling power. For the LTC4231-2

auto-retry option, the current fault latch is cleared auto-

matically and the GATE is ramped up after a 500ms delay.

UVH, UVL: Undervoltage Comparator Input. Connect

these pins to an external resistive network to monitor

IN for UV. These pins connect internally to an undervolt-

age comparator with a 0.795V threshold. The comparator

monitors UVH when GATE is low and UVL when GATE

is high to implement separate undervoltage turn-on and

undervoltage turn-off thresholds. To reduce the power

dissipated by this resistive divider, the LTC4231 periodi-

cally samples IN by connecting GNDSW to GND once

every 10ms. Once an UV is detected at these pins, GATE

and STATUS pull low. Tie both pins to IN if unused. When

connected to IN, for applications where IN goes below

ground, use a resistor to limit the current to ≤1mA.

Exposed Pad (QFN Package): The exposed pad may be

left open or connected to device ground.

LTC4231

Rev. B

For more information www.analog.com

FUNCTIONAL DIAGRAM

4231 FD

IN SENSE

VOLTAGE

REGULATOR

–

+REVERSE

VOLTAGE

COMPARATOR

–

REVERSE

VOLTAGE

COMPARATOR

∆VGATE LOW

COMPARATOR

∆VGATE(H)

ANALOG CURRENT

LIMIT AMPLIFIER

–

CHARGE PUMP

REFRESH

TIMER

80mV

–

CIRCUIT BREAKER

COMPARATOR

TIMER HIGH COMPARATOR

TIMER LOW COMPARATOR

–

50mV

–

1.2V

15V

0.795V

1mA

CHARGE

PUMP

f = 2MHz

GATE LOW

COMPARATOR

–

0.795V

–

UV COMPARATOR

OV/UV BLOCK

OV COMPARATOR

10µA

LOGIC

INTERNAL VCC

1.193V

0.1V

UVL

SOURCE

GATE

UVH

GNDSW

STATUS

OV/UV

STROBE

TIMER

SHDN GND

5µA

50µA

TIMER

LTC4231

Rev. B

For more information www.analog.com

OPERATION

The LTC4231 is a micropower Hot Swap controller that

controls an external N-channel MOSFET to turn on and

off a supply voltage in a controlled manner. This allows a

circuit to be safely inserted and removed from a powered

connector without glitches or connector damage from

uncontrolled inrush current.

When the LTC4231 is first powered up, the gate of the

MOSFET is held at GND to keep it off. Pulling SHDN

high and IN above undervoltage lockout (UVLO) starts

an internal clock that monitors the resistive divider at IN

once every 10ms by connecting GNDSW to GND. A 40ms

debounce cycle is also started. Average I

during this

debounce mode is 4µA.

After the 40ms debounce cycle, the LTC4231 goes into

start-up mode to ramp up GATE. In this mode, all circuits

blocks except the overvoltage or undervoltage (OV/UV)

block are activated and ICC = 300µA. The internal charge

pump supplies a 10µA pull-up current to GATE. Once

∆VGATE exceeds ∆VGATE(H), STATUS goes high impedance.

This indicates that GATE is high and the power path is on.

Average ICC drops to 4µA during this normal on mode as

some circuit blocks are shut down and the internal charge

pump periodically turns on to recharge GATE as needed.

The periodic monitoring of the IN resistive divider contin-

ues as long as SHDN is high and IN ≥ 2.3V.

If an OV/UV violation is detected during the IN monitor-

ing time, the part goes into voltage fault mode (average

= 4µA) where GATE and STATUS is pulled to GND.

The debounce cycle restarts when no OV/UV violation

is detected during a subsequent IN monitoring window.

The LTC4231 has a circuit breaker comparator that moni-

tors the voltage across the current sense resistor. This

comparator trips when ∆VSENSE exceeds 50mV, bring-

ing the LTC4231 into overcurrent mode. In this mode, all

circuits blocks except the OV/UV block are activated and

ICC = 300µA. If ∆VSENSE > 80mV, the analog current limit

amplifier limits ∆VSENSE to 80mV by servoing ∆VGATE in

an active control loop. The TIMER capacitor is ramped up

with a 50µA pull-up when ∆VSENSE > 50mV. When TIMER

> 1.193V, the current fault latch is set, causing GATE and

STATUS to pull low. The part goes into current fault mode.

In current fault mode, the latchoff (LTC4231-1) version

keeps TIMER and GATE low. The auto-retry (LTC4231-2)

version waits 500ms before GATE is ramped up again.

For both versions, the part can be reset by cycling SHDN

low then high or by cycling IN to GND and back. After the

reset, the LTC4231 goes through a debounce cycle before

re-starting GATE.

SHDN acts as a shutdown switch for the supply path.

When it goes high, the LTC4231 ramps GATE up after a

debounce cycle to turn on the external MOSFET. When it

goes low, GATE is pulled to GND to turn off the external

MOSFET. The LTC4231 then goes into shutdown mode

where ICC drops to 0.3µA.

IN, SENSE, GATE and SOURCE are protected against

reverse inputs of up to –40V. Two reverse voltage com-

parators detect negative input potentials at SENSE or

GATE and quickly connect GATE to SENSE. When used

with back-to-back MOSFETs as shown in Figure5, this

feature will isolate the load from a negative input.

LTC4231

Rev. B

For more information www.analog.com

The micropower capability of the LTC4231 makes it ideal

for Hot Swap applications in battery powered systems

where current load is light or intermittent and power draw

is a concern. It can implement battery short circuit pro-

tection, reverse battery protection, battery voltage moni-

toring, power path control, hot-plug and inrush current

control in off-grid, autonomous systems.

Turn-On Sequence

When IN is less than the UVLO level of 2.3V or SHDN is

low, GATE is pulled to GND and STATUS pulls low. When

IN ≥ 2.3V and SHDN goes high, an internal clock starts

timing a 40ms debounce cycle. The clock also times a

200µs strobe of the resistive divider at IN every 10ms

to make sure IN is not in OV/UV. Average ICC during this

debounce mode is 4µA.

Any OV/UV detected will stop and reset the debounce

timing cycle. During this voltage fault mode, average ICC

is 4µA. The debounce cycle only restarts when a subse-

quent IN strobe indicates that the input power is within

the acceptable range, IN ≥ 2.3V and SHDN is high.

When the debounce cycle of 40ms successfully com-

pletes, the LTC4231 turns on its charge pump, analog

current limit amplifier and TIMER control circuit blocks

APPLICATIONS INFORMATION

as it goes into start-up mode (ICC = 300µA). The external

MOSFET is turned on by charging up the GATE with a

10μA charge pump generated current source.

At start-up, the MOSFET current is typically dominated by

the current charging the load capacitor CL. If ∆VSENSE >

80mV, the analog current limit amplifier controls the gate

of the MOSFET in a closed loop. This keeps the start-up

inrush current at 80mV/RSENSE. When ∆VSENSE > 50mV,

the TIMER capacitor charges up with an internal 50µA

pull-up current.

Figure2. Inrush Control by Analog Current Limit

SENSE GATE

UVL

UVH

GNDSW

SOURCE

STATUS

SHDN

TIMER

LTC4231

Si7120ADN

RSENSE

22.5mΩ

GND

RSTAT

20k

1nF

10Ω

20nF

VOUT

24V

GND

1020k

SMAJ24A

CIN

100µF

1.65k

24V

BATTERY

CELL(S)

UV RISING = 23V

UV FALLING = 22V

OV RISING = 26V

4.22k

32.4k

39nF

ILOAD

4231 F01

10M

1000µF

Figure1. Channel Controller with Connector Enable

GATE

20V/DIV

OUT

20V/DIV

TIMER

0.5V/DIV

ILOAD

2A/DIV

1ms/DIV

START-UP NORMAL ONDEBOUNCE

4231 F02

LTC4231

Rev. B

For more information www.analog.com

APPLICATIONS INFORMATION

In most applications, keeping the inrush current at ana-

log current limit is an acceptable start-up method if the

TIMER delay is long enough to avoid setting the current

fault latch and the MOSFET has adequate safe operating

margin. However, for more flexibility in design (See the

Design Example section), a capacitor from GATE to GND

(Figure1) can be used to limit the VGATE slew rate for inrush

current control. V

GATE

rises with a slope equal to 10μA/C

(Figure3). The supply inrush current is then limited to:

IINRUSH =CL

•10µA

Once ∆VGATE exceeds ∆VGATE(H), STATUS goes high

impedance. ICC drops from 300µA to 4µA (average) dur-

ing this normal on mode as some circuit blocks are shut

down and the internal charge pump periodically turns on

when ∆VGATE droops by 0.7V or every 15ms, whichever

comes first (Figure7).

In the back-to-back MOSFET configuration as shown in

Figure5, SOURCE will also be pulled to GND via the para-

sitic body diode between GATE and SOURCE, cutting off

the load from IN. This configuration is suitable in power

path control and reverse battery protection applications

where IN is likely to go below GND.

In the single MOSFET configuration (Figure1), the 1mA

pull-down from GATE to GND also discharges the load

capacitor CL to GND once GATE goes below SOURCE.

Overcurrent Fault

The 50mV circuit breaker threshold sets the maximum

load current allowed under steady state conditions.

However, the LTC4231 allows mild overcurrents during

supply or load transients when ∆VSENSE momentarily

exceeds 50mV but stays below the 80mV analog current

limit threshold. For severe overcurrents when ∆V

SENSE

exceeds 80mV, the analog current limit amplifier controls

∆VGATE to regulate ∆VSENSE to 80mV. The durations of

these transient overcurrents must be less than the cir-

cuit breaker delay (tCB) which can be adjusted using the

capacitor CT at the TIMER pin.

When ∆V

SENSE

exceeds 50mV, the LTC4231 goes into

overcurrent mode. CT is charged with a 50μA pull-up.

If the overcurrent is transient and ∆V

SENSE

goes below

50mV before TIMER reaches 1.193V, the 50μA pull-up

on TIMER switches to a 5μA pull-down. Multiple overcur-

rents with a duty cycle > 10% can thus eventually inte-

grate TIMER to 1.193V. When TIMER reaches 1.193V, the

LTC4231 goes into current fault mode and sets an internal

current fault latch. The external MOSFET will be cut off

by a 1mA pull-down from GATE to GND while STATUS

pull-down is asserted.

The time in which LTC4231 stays in overcurrent mode

before going into current fault mode is called the circuit

breaker delay and is given by:

tCB = CT • 24 [ms/µF]

Figure3. Inrush Control by Limiting VGATE Slew

GATE

20V/DIV

OUT

20V/DIV

ILOAD

0.5A/DIV

20ms/DIV 4231 F03

START-UP NORMAL ON

DEBOUNCE

Turn-Off Sequence

The MOSFET switch can be turned off by SHDN going low,

an OV/UV event, an overcurrent setting the current fault

latch or IN dropping below its UVLO voltage. Under any

of these conditions, STATUS pulls low and the MOSFET

is turned off with a 1mA current pulling down from GATE

to GND.

LTC4231

Rev. B

For more information www.analog.com

APPLICATIONS INFORMATION

SOURCE

GATE

SHDN

STATUS

VOLTAGE FAULT

∆VSENSE

TIMER

GNDSW

DEBOUNCE START-UP START-UPNORMAL ON

OVER-

CURRENT

FAULT

SHUT-

DOWN DEBOUNCE NORMAL ON

4µA 4µA 4µA 4µA

300µA 300µA 300µA

AVERAGE

ICC

200µs

0.3µA

4µA

(IGATE(LEAKAGE) ≤ 0.1µA)

4µA

(IGATE(LEAKAGE) ≤ 0.1µA)

VOVOFF

40ms tCB 40ms

4231 F04

∆VSENSE(CB)

∆VGATE(H)

0.7V

VTIMER(H)

VTIMER(L)

Figure4. LTC4231-1 Overcurrent

LTC4231

Rev. B

For more information www.analog.com

APPLICATIONS INFORMATION

Auto-Retry vs Latchoff

During current fault mode, GATE is held low and TIMER is

discharged to GND. Once TIMER < 0.1V, average ICC goes

to 4µA and the internal current fault latch is ready to be

reset. The LTC4231-2 (automatic retry) waits for a 500ms

retry delay after which the internal current fault latch is

reset and GATE ramps up to turn the MOSFET back on.

The LTC4231-1 (latchoff) version does not restart auto-

matically. Pulling SHDN low for >100µs will reset the

internal current fault latch. When SHDN goes high, GATE

ramps up after a debounce cycle. Alternatively, IN can be

pulled to GND for >100µs then cycled back up again. This

UVLO event will reset the internal current fault latch and

GATE ramps up after a debounce cycle. A UV/OV detected

at IN also resets the internal current fault latch and GATE

ramps up after a debounce delay.

Analog Current Limit Loop Stability

The analog current limit loop on GATE is compensated by

the parasitic gate capacitance of the external MOSFET. No

further compensation components are normally required.

If a small MOSFET with CISS ≤ 1nF is chosen, an RG and

CG compensation network connected at GATE may be

required (Figure1) to ensure stability. The resistor, RG,

connected in series with CG accelerates the MOSFET

gate recovery after a fast gate pull-down. The value of

CG should be ≤100nF. An additional 10Ω resistor (R5 in

Figure1) should be added close to the MOSFET gate to

prevent possible parasitic oscillation due to trace/wire

inductance and capacitance.

Monitor OV and UV Faults

When IN is above UVLO and SHDN is high, an internal

clock times a 200µs strobe of the resistive divider at IN

every 10ms. During this 200µs strobe, the normally high

impedance GNDSW is connected to GND with an internal

80Ω switch and the comparators connected to UVH, UVL

and OV are awakened from sleep mode. The comparators

sense the voltages on the resistive divider, and their out-

puts are latched at the end of the strobe window.

If an OV or UV violation is detected, the STATUS pulls

low and a 1mA pull-down will be activated between GATE

and GND to turn off the external MOSFET. When GATE

goes <1.2V, average ICC drops to 4µA as the LTC4231

goes into voltage fault mode. It stays in this mode until a

subsequent IN strobe sees no OV/UV. The LTC4231 then

re-starts after a debounce cycle.

Strobing the resistive divider reduces power consumption

as the external resistors as well as the internal OV/UV

comparators do not dissipate power in between strobes.

For a 1M string of resistors used to monitor a VIN of 24V,

this strobing scheme reduces the current consumption

from 24µA to 0.48µA as the strobing duty cycle is 2%

(200µs/10ms). The OV/UV comparators dissipate 35µA

during IN strobing. The 2% duty cycle reduces this to an

average current of 0.7µA. Note that the response time to

an OV/UV event can be as long as 10ms.

The four resistors allow three thresholds to be configured.

They are the UV rising threshold (VUVON), the UV falling

threshold (VUVOFF) and the OV rising threshold (VOVOFF).

The OV falling threshold is set by internal hysteresis to be

1.8% below the OV rising threshold. Using the compara-

tor threshold as 0.795V and choosing appropriate values

for RTOTAL and R4, the resistor values can be calculated

as follows:

RTOTAL =R1+R2+R3+R4

R4 =0.795V

VOVOFF

⎛

⎝

⎜

⎞

⎠

⎟•RTOTAL

R3 =VOVOFF

VUVON

−1

⎛

⎝

⎜

⎞

⎠

⎟•R4

R2 =VUVON

VUVOFF

−1

⎛

⎝

⎜

⎞

⎠

⎟•VOVOFF

VUVON

⎛

⎝

⎜

⎞

⎠

⎟•R4

R1=UOVOFF

0.795V −1

⎛

⎝

⎜⎞

⎠

⎟•R4−R3 −R2

It is recommended that the total value of the resistor

string be less than 2M and traces at UVH, UVL, and OV

kept short to minimize parasitic capacitance and improve

settling time.

LTC4231

Rev. B

For more information www.analog.com

APPLICATIONS INFORMATION

Reverse Input Protection

Negative voltages at IN can occur if a battery is plugged

in backwards or a negative supply is inadvertently con-

nected. Back-to-back N-channel MOSFETs can be used as

in Figure5 to prevent the negative voltage from passing

to the output load.

IN, SENSE, GATE and SOURCE are protected against

reverse inputs of up to –40V. When the LTC4231's

reverse voltage comparators detect a negative voltage at

SENSE, an internal switch is activated to connect GATE to

SENSE. The body diode of M1 pulls SOURCE to a diode

above SENSE. Since M2 is off and its body diode is in the

reverse blocking mode, the negative voltage is blocked by

the VDS of M2.

Figure6 shows the waveforms when the application cir-

cuit in Figure5 is hot plugged to –24V. Due to the para-

sitic inductance at IN, SENSE and GATE, the voltages ring

significantly below –24V. The TransZorb helps to clamp

the negative undershoot and a 40V MOSFET is selected

for M2 to survive this undershoot.

Figure5. Back-to-Back MOSFETs Protect Against Reverse Input

Figure6. LTC4231 in Reverse Input Mode

SENSE GATE

UVL

UVH

GNDSW

SOURCE

STATUS

SHDN

TIMER

LTC4231

Si7164DP

SMAJ24CA

RSENSE

22.5mΩ M2

Si5410DU

GND

RSTAT

20k

100µF

UV RISING = 23V

UV FALLING = 22V

OV RISING = 26V

VOUT

24V

1020k

10Ω

0.1µF

1.65k

24V

4.22k

32.4k

82nF

ILOAD

4231 F05

GATE

20V/DIV

OUT

20V/DIV

1µs/DIV 4231 F06

LTC4231

Rev. B

For more information www.analog.com

APPLICATIONS INFORMATION

Achieving Low Quiescent Current

Table1 summarizes the average ICC of the various operat-

ing modes of the LTC4231.

Table1.

MODE ICC (NORM) ICC (MAX)

Start-Up or Overcurrent 300µA 600µA

Debounce, Normal On, Voltage or

Current Fault

4µA 10µA

Shutdown 0.3µA 1µA

Reverse Input –2.5mA –5mA

To lower ICC when GATE is high, the LTC4231 operates in

normal on mode, where the charge pump delivers pulses

of current to the GATE capacitance (either an external

CG or the parasitic capacitance of the external MOSFETs)

to boost ∆VGATE to ∆VGATE(H) followed by sleep periods

when the GATE capacitance holds up GATE. Leakage will

cause ∆VGATE to droop during these sleep periods. When

the ∆VGATE low comparator detects ∆VGATE drooping by

more than 0.7V, it will activate the charge pump to boost

∆VGATE back to ∆VGATE(H) before returning to sleep mode.

In addition to the ∆VGATE low comparator, there is a charge

pump refresh timer that turns on the charge pump every

15ms to boost ∆V

GATE

back to ∆V

GATE(H)

. This timer is

reset when the charge pump turns on.

When in charge pump sleep mode the LTC4231 con-

sumes 2µA. When the charge pump is on to deliver a

Figure7. Regulating ∆VGATE During Normal On Mode Figure8. SHDN Going Low Activates Shutdown Mode

∆VGATE

2V/DIV

ICC

200µA/DIV

5ms/DIV 4231 F07

IGATE = –0.1µA IGATE = –1µA

GATE

20V/DIV

SOURCE

20V/DIV

STATUS

20V/DIV

SHDN

5V/DIV

20µs/DIV

ENTERS

SHUTDOWN MODE

4231 F08

current pulse to GATE, ICC briefly goes up to 200µA. The

amount of leakage at GATE (IGATE(LEAKAGE)) will determine

the duty cycle of the charge pump. Figure7 shows start-

up and ∆VGATE regulation (with different IGATE(LEAKAGE))

waveforms from the Figure5 application circuit.

As the average current delivered to GATE during the cur-

rent pulse is around 15µA, the duty cycle of the charge

pump for a IGATE(LEAKAGE) of 0.1µA is 0.1/15 = 0.67%. The

average current due to ∆VGATE regulation is then 0.67%

• 200µA = 1.3µA. When added to the average current

due to OV/UV strobing (0.7µA) and charge pump sleep

mode current (2µA), the average quiescent current of the

LTC4231 during the normal on mode is 1.3µA + 0.7µA +

2µA = 4µA. The normal on mode average supply current

can be estimated using the formula:

CC =

2.7µA

13.3 •I

GATE(LEAKAGE)

The Typical Performance Characteristics section shows a

graph of average ICC (normal on) against IGATE(LEAKAGE).

Shutdown Mode

When SHDN goes low, STATUS pulls low and a 1mA pull-

down will be activated between GATE and GND to cut

off the external MOSFET. When GATE reaches <1.2V, ICC

drops to 0.3µA as the LTC4231 goes into shutdown mode.

When SHDN goes high, GATE ramps up after the 40ms

debounce cycle. Figure8 shows the application in Figure5

going into shutdown mode.

LTC4231

Rev. B

For more information www.analog.com

APPLICATIONS INFORMATION

Supply Transient Protection

When the capacitances at the input and output are very

small, rapid changes in current during an output short-

circuit event can cause transients that exceed the 40V

absolute maximum ratings of IN, SENSE and SOURCE.

To minimize such spikes, use wider traces or heavier

trace plating to reduce the power trace inductance. Also,

bypass locally with a 10μF electrolytic and 0.1μF ceramic

if hot plug inrush current is not a concern. Alternatively,

clamp the input with a transient voltage suppressor (Z1

in Figure5). A 10Ω, 0.1μF snubber damps the response

and reduces ringing (RX and CX inFigure5).

Design Example

As a design example, take the following specifications for

the Figure5 application circuit. The application is rated

for a VIN of 24V at 2A, CL = 100µF. UV rising = 23V, UV

falling = 22V, OV rising = 26V.

Sense resistor:

RSENSE =ΔVSENSE(CB)(MIN)

=47mV

=23.5mΩ

Use RSENSE = 22.5mΩ for margin. Worst case analog

current limit:

ILIMIT(MIN) =Δ

SENSE(ACL)(MIN)

22.5mΩ=65mV

22.5mΩ=2.89A

ILIMIT(MAX) =ΔVSENSE(ACL)(MAX)

22.5mΩ

=90mV

22.5mΩ

=4A

Calculate the worst case time it takes to charge up CL in

analog current limit:

tCHARGE(MAX) =CL• VIN

ILIMIT(MIN)

=100µF • 24V

2.89A =0.9ms

For inrush control using analog current limit, t

CHARGE(MAX)

must be less than the circuit breaker delay (tCB) for a

proper start-up.

The worst case power dissipation in MOSFET M1 occurs

during a severe overcurrent fault when the current is con-

trolled by analog current limit for the duration of tCB:

PDISS = VIN • ILIMIT(MAX) = 24V • 4A = 96W

The SOA (safe operating area) curve for the Si7164DP

MOSFET shows that it can withstand 180W for 10ms. So

choose a tCB that is less than 10ms but higher than 0.9ms

(tCHARGE(MAX)). In this case, use tCB = 2ms.

CT=

=2ms

=0.082µF =82nF

If a low inrush current (< ∆VSENSE(CB)) is preferred, refer

to the Figure1 application circuit which uses a gate capac-

itor CG to limit the inrush current. Choose IINRUSH = 0.5A

which is set using CG:

CG=CL

INRUSH

•10µA =1000µF

0.5A •10µA =20nF

The time to charge up CL with 0.5A is:

tCHARGE =CL• VIN

INRUSH

=1000µF • 24V

0.5A =48ms

In this case tCHARGE can be longer than tCB with no start-

up issue.

The average power dissipation in the MOSFET M1 during

this start-up is:

PDISS =

•I

INRUSH

=24V • 0.5A

=6W

The SOA of the MOSFET M1 must be evaluated to ensure

that it can withstand 6W for 48ms. The SOA curve of the

Si7120ADN withstands 10W for 360ms, satisfying the

requirement.

The purpose of MOSFET M2 is to block the reverse path

from OUT (drain of M2) to IN when GATE pulls to GND so

that IN can go lower than OUT or even negative. Choose a

40V MOSFET to withstand a worse case reverse DC volt-

age of –24V. The Si5410DU offers a good choice with a

maximum RDS(ON) of 18mΩ at VGS = 10V.

LTC4231

Rev. B

For more information www.analog.com

APPLICATIONS INFORMATION

The IN monitoring resistors R1–R4 should be chosen to

yield a total divider resistance of between 1M to 2M for

both low power and good transient response. Using the

formulas from the Monitor OV and UV Faults section,

R1–R4 are calculated as follows (with all resistor values

rounded up to the nearest 1% accurate standard values):

Choose R1 + R2 + R3 + R4 = 1000kΩ

R4 =0.795V

VOVOFF

⎛

⎝

⎜

⎞

⎠

⎟•1000kΩ

Choose R4 = 32.4kΩ to give total divider resistance: R1

+ R2 + R3 + R4 = 1060kΩ.

R3 =VOVOFF

VUVON

−1

⎛

⎝

⎜

⎞

⎠

⎟•R4 =26V

23V −1

⎛

⎝

⎜⎞

⎠

⎟• 32.4kΩ = 4.22kΩ

R2 =VUVON

VUVOFF

−1

⎛

⎝

⎜

⎞

⎠

⎟•VOVOFF

VUVON

⎛

⎝

⎜

⎞

⎠

⎟•R4

=23V

22V −1

⎛

⎝

⎜⎞

⎠

⎟•26V

23V

⎛

⎝

⎜⎞

⎠

⎟• 32.4kΩ = 1.65kΩ

R1=VOVOFF

0.795V −1

⎛

⎝

⎜⎞

⎠

⎟•R4−R3 −R2

=26V

0.795V −1

⎛

⎝

⎜⎞

⎠

⎟• 32.4kΩ − 4.22kΩ −1.65kΩ = 1020kΩ

Layout Considerations

To achieve accurate current sensing, a Kelvin connection

for the sense resistor is recommended. The PCB layout

for the resistor should be balanced and symmetrical to

minimize wiring errors. In addition, the PCB layout for the

sense resistors and the power MOSFETs should include

good thermal management techniques for optimal device

power dissipation. In Hot Swap applications where load

currents can be high, narrow PCB tracks exhibit more

resistance than wider tracks and operate at elevated tem-

peratures. 1oz copper exhibits a sheet resistance of about

0.5mΩ/square. The minimum trace width for 1oz copper

foil is 0.5mm per amp to make sure the trace stays at a

reasonable temperature. Using 0.8mm per amp or wider

is recommended. Thicker top and bottom copper such as

3oz or more can improve electrical conduction and reduce

PCB trace dissipation.

If a resistor R5 (see Figure1) is used, place it as close as

possible to M1's gate input. This will limit the parasitic

trace capacitance that leads to M1 self-oscillation. The

transient voltage suppressor, Z1, when used, should be

mounted close to the LTC4231 using short lead lengths.

A recommended PCB layout for the sense resistor and

back-to back power MOSFETs is shown in Figure9.

LTC4231

MOSFET M1

MOSFET M2

RSENSE

RSTAT

4231 F09

Figure9. Recommended Layout

LTC4231

Rev. B

For more information www.analog.com

APPLICATIONS INFORMATION

SENSE GATE

UVL

UVH

GNDSW

SHDN

SOURCE

STATUS

TIMER

LTC4231

LTC2955-1

Si7120ADN

INT

KILL

TIMER

VIN

SMAJ28CA

RSENSE

45mΩ M2

Si5410DU OUT

GND

100µF

UV RISING = 25V

UV FALLING = 24V

OV RISING = 28.5V

VOUT

25V

1070k

RIN

10k

CIN

100nF

1.47k

25V

4.32k

RSTAT

4.7M

30.9k

GND

180nF

4231 F10

Figure10. Micropower Push Button and Hot Swap Controllers with Reverse Battery Protection

Additional Applications

Figure10 shows a reverse-battery protected application

featuring the LTC2955 micropower push-button con-

troller. A press on the push button switch will turn on

the LTC4231 while a subsequent press will turn off the

LTC4231. In the event the LTC4231 is unable to power-up

successfully when EN goes high, the STATUS output is

fed back to the KILL input in order to place the LTC4231

back in the very low-power Shutdown mode.

Figure11 illustrates a 36V application with an UV rising

threshold of 35V, an UV falling threshold of 33V and an

OV rising threshold of 38V. As the IN operating voltage

is so near to its 40V absolute maximum rating, a suitable

TransZorb is not available to protect IN. Instead, a float-

ing GND architecture is used to help the LTC4231 survive

possible voltage transients during short circuit events.

This architecture is strictly for handling IN transients dur-

ing 36V operation. It does not allow DC VIN operation >

39V.

LTC4231

Rev. B

For more information www.analog.com

PACKAGE DESCRIPTION

MSOP (MS12) 0213 REV A

0.53 ±0.152

(.021 ±.006)

SEATING

PLANE

0.18

(.007)

1.10

(.043)

MAX

0.22 –0.38

(.009 – .015)

TYP

0.86

(.034)

REF

0.650

(.0256)

BSC

12 11 10 9 8 7

NOTE:

1. DIMENSIONS IN MILLIMETER/(INCH)

2. DRAWING NOT TO SCALE

3. DIMENSION DOES NOT INCLUDE MOLD FLASH, PROTRUSIONS OR GATE BURRS.

MOLD FLASH, PROTRUSIONS OR GATE BURRS SHALL NOT EXCEED 0.152mm (.006") PER SIDE

4. DIMENSION DOES NOT INCLUDE INTERLEAD FLASH OR PROTRUSIONS.

INTERLEAD FLASH OR PROTRUSIONS SHALL NOT EXCEED 0.152mm (.006") PER SIDE

5. LEAD COPLANARITY (BOTTOM OF LEADS AFTER FORMING) SHALL BE 0.102mm (.004") MAX

0.254

(.010) 0° – 6° TYP

DETAIL “A”

GAUGE PLANE

5.10

(.201)

MIN

3.20 – 3.45

(.126 – .136)

0.889 ±0.127

(.035 ±.005)

RECOMMENDED SOLDER PAD LAYOUT

0.42 ±0.038

(.0165 ±.0015)

TYP

0.65

(.0256)

BSC

4.039 ±0.102

(.159 ±.004)

(NOTE 3)

0.1016 ±0.0508

(.004 ±.002)

1 2 3 4 5 6

3.00 ±0.102

(.118 ±.004)

(NOTE 4)

0.406 ±0.076

(.016 ±.003)

REF

4.90 ±0.152

(.193 ±.006)

MS Package

12-Lead Plastic MSOP

(Reference LTC DWG # 05-08-1668 Rev A)

LTC4231

Rev. B

For more information www.analog.com

PACKAGE DESCRIPTION

3.00 ± 0.10

(4 SIDES)

RECOMMENDED SOLDER PAD PITCH AND DIMENSIONS

1.65 ±0.05

(4 SIDES)

NOTE:

1. DRAWING CONFORMS TO JEDEC PACKAGE OUTLINE MO-220 VARIATION (WEED-1)

2. DRAWING NOT TO SCALE

3. ALL DIMENSIONS ARE IN MILLIMETERS

4. DIMENSIONS OF EXPOSED PAD ON BOTTOM OF PACKAGE DO NOT INCLUDE

MOLD FLASH. MOLD FLASH, IF PRESENT, SHALL NOT EXCEED 0.15mm ON ANY SIDE

5. EXPOSED PAD SHALL BE SOLDER PLATED

6. SHADED AREA IS ONLY A REFERENCE FOR PIN 1 LOCATION

ON THE TOP AND BOTTOM OF PACKAGE

PIN 1

TOP MARK

(NOTE 6)

0.40 ±0.10

BOTTOM VIEW—EXPOSED PAD

1.65 ±0.10

(4-SIDES)

0.75 ±0.05 R = 0.115

TYP

0.25 ±0.05

PIN 1 NOTCH R = 0.20 TYP

OR 0.25 × 45° CHAMFER

11 12

0.50 BSC

0.200 REF

2.10 ±0.05

3.50 ±0.05

0.70 ±0.05

0.00 – 0.05

(UD12) QFN 0709 REV Ø

0.25 ±0.05

0.50 BSC

PACKAGE OUTLINE

UD Package

12-Lead Plastic QFN (3mm × 3mm)

(Reference LTC DWG # 05-08-1855 Rev Ø)

LTC4231

Rev. B

For more information www.analog.com

Information furnished by Analog Devices is believed to be accurate and reliable. However, no responsibility is assumed by Analog

Devices for its use, nor for any infringements of patents or other rights of third parties that may result from its use. Specifications

subject to change without notice. No license is granted by implication or otherwise under any patent or patent rights of Analog Devices.

REVISION HISTORY

REV DATE DESCRIPTION PAGE NUMBER

A 09/15 Added H-grade information

Updated specifications: VGATE(L), IGATE(UP), tD(ON), tRETRY, tPERIOD, tSAMPLE, tCB

2, 3, 4

3,4

B 08/19 Added AEC-Q100 1, 3

LTC4231

Rev. B

For more information www.analog.com

 ANALOG DEVICES, INC. 2014-2019

08/19

www.analog.com

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LTC2960 Nano-Current Dual Voltage Monitor 850nA IQ, 2.5V to 36V Operation, 1.5% Accuracy

LTC4229 Ideal Diode and Hot Swap Controller 2.9V to 18V Operation, 2mA IIN, 0.5µs Ideal Diode Turn-On/Off

LTC4232 5A Integrated Hot Swap Controller Integrated 33mΩ MOSFET with Sense Resistor, 2.9V to 15V Operation

LTC2955 Pushbutton On/Off Controller Automatic Turn-On, 1.2µA IQ, 1.5V to 36V Operation

LTC4417 Prioritized PowerPath™ Controller 28µA IQ, 2.5V to 36V Operation, –42V Reverse Input

Figure11. 36V Hot Swap Application with Reverse Protection

SENSE GATE

UVL

UVH

GNDSW

SHDN

SOURCE

STATUS

TIMER

LTC4231

Si7164DP

RSENSE

45mΩ

GND

Si7120ADN OUT

RSTAT

VOUT

36V

787k

10Ω Z2

BZX84C39

0.1µF

1.1k

UV RISING = 35V

UV FALLING = 33V

OV RISING = 38V

1.43k

16.9k

270nF

10nF

4231 F11

SMBJ36CA

36V

100µF

300Ω