LINEAR TECHNOLOGY LTC4223-1, LTC4223-2 Technical data

LTC4223-1/LTC4223-2

Dual Supply Hot Swap

Controller for Advanced

Mezzanine Card

FEATURES

■

Allows Safe Insertion into Live AMC or MicroTCA

Backplane

■

Controls 12V Main and 3.3V Auxiliary Supplies

■

Limits Peak Fault Current in ≤1μs

■

Adjustable Current Limit with Circuit Breaker

■

Integrated 0.3Ω AUX Switch

■

High Side Current Sense

■

Gate Drive for External N-Channel MOSFET

■

Adjustable Response Time for Overcurrent Protection

■

Adjustable Supply Voltage Power-Up Rate

■

Thermal Shutdown Protection

■

LTC4223-1: Latch Off After Fault

■

LTC4223-2: Automatic Retry After Fault

■

16-Lead SSOP and 5mm × 4mm DFN Packages

APPLICATIONS

■

Advanced Mezzanine Card, MicroTCA Systems

■

Workstations and Server I/O

■

Telecom Networks

DESCRIPTION

The LTC®4223 positive voltage Hot SwapTM controller allows a board to be safely inserted and removed from a live AMC or MicroTCA backplane. It controls the main 12V supply with an external N-channel MOSFET and the

3.3V auxiliary supply with an integrated switch. The 12V output ramp rate is adjustable and includes inrush current limiting. The 12V output is also protected against short circuit faults with a fast acting current limit and a 5% accurate timed circuit breaker. The 3.3V output includes both soft start and overcurrent protection.

The LTC4223 features a current monitor output for the 12V supply, and reports fault and power-good status for both supplies. It also detects card presence and allows independent control of the 12V and auxiliary 3.3V supply outputs. The LTC4223-1 features a latch-off circuit breaker, while the LTC4223-2 provides automatic retry after a fault.

, LT, LTC and LTM are registered trademarks of Linear Technology Corporation.

All other trademarks are the property of their respective owners.

TYPICAL APPLICATION

Advanced Mezzanine Card Application

6mΩ Si7336ADP

12V

SENSE

IN

AUXIN

V

CC

AUXON 12ON AUXPGOOD 12PGOOD FAULT

12IMON

GND

10Ω

47Ω

12V

GATE

LTC4223-1/LTC4223-2

TIMER

0.1μF

IPMC

12V

3.3V

51Ω

330nF

ADC

15nF

12V

OUT

AUXOUT

422312 TA01a

EN

CARRIER

CONNECTOR

12V

7.4A

3.3V 150mA

MODULE CONNECTOR

EN

5V/DIV

AUXOUT

5V/DIV

12V

OUT

5V/DIV

AUXPGOOD

5V/DIV

12PGOOD

5V/DIV

Normal Power-Up Waveform

20ms/DIV

422312 TA01b

422312f

1

LTC4223-1/LTC4223-2

ABSOLUTE MAXIMUM RATINGS

(Note 1)

Supply Voltages 12V

..................................................... –0.3V to 20V

IN

AUXIN .................................................... –0.3V to 10V

........................................................... –0.3V to 7V

V

CC

Input Voltages

⎯E⎯

12ON, AUXON,

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

12V

............................................... –0.3V to 20V

SENSE

N ................................... –0.3V to 7V

+ 0.3V

CC

Output Voltages

⎯F⎯A⎯U⎯L⎯

T, ⎯1⎯2⎯P⎯G⎯O⎯O⎯D, ⎯A⎯U⎯X⎯P⎯G⎯O⎯O⎯D,

12IMON ................................................... –0.3V to 7V

PIN CONFIGURATION

12V 12V

................................................. –0.3V to 25V

GATE OUT

- 12V

(Note 3) ................... –4.5V to 0.3V

GATE

AUXOUT ................................................. –0.3V to 10V

Operating Temperature Range

LTC4223-1C/ LTC4223-2C ....................... 0°C to 70°C

LTC4223-1I/ LTC4223-2I ..................... –40°C to 85°C

Storage Temperature Range

GN Package .......................................–65°C to 150°C

DHD Package ..................................... –65°C to 125°C

Lead Temperature (Soldering, 10sec)

GN Package ......................................................300°C

12V

12IMON

AUXON

SENSE

12V

12ON

AUXIN

V

GND

IN

CC

T

JMAX

TOP VIEW

1

2

3

4

5

6

7

8

GN PACKAGE

16-LEAD PLASTIC SSOP

= 125°C, θJA = 110°C/W

16

15

14

13

12

11

10

9

12V

GATE

12V

OUT

12PGOOD

FAULT

AUXOUT

AUXPGOOD

EN

TIMER

12V

SENSE

12V

12IMON

12ON

AUXIN

AUXON

GND

16-LEAD (5mm × 4mm) PLASTIC DFN

EXPOSED PAD (PIN 17) PCB GND CONNECTION OPTIONAL

MUST BE SOLDERED TO PCB TO OBTAIN

= 43°C/W, OTHERWISE θJA = 140°C/W, T

θ

JA

IN

V

CC

TOP VIEW

1

2

3

4

5

6

7

8

DHD PACKAGE

16

12V

GATE

15

12V

OUT

14

12PGOOD

13

12

11

10

9

FAULT

AUXOUT

AUXPGOOD

EN

TIMER

JMAX

= 125°C

17

ORDER INFORMATION

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

LTC4223CDHD-1#PBF LTC4223CDHD-1#TRPBF 42231 16-Lead (5mm × 4mm) Plastic DFN 0°C to 70°C

LTC4223CDHD-2#PBF LTC4223CDHD-2#TRPBF 42232 16-Lead (5mm × 4mm) Plastic DFN 0°C to 70°C

LTC4223IDHD-1#PBF LTC4223IDHD-1#TRPBF 42231 16-Lead (5mm × 4mm) Plastic DFN –40°C to 85°C

LTC4223IDHD-2#PBF LTC4223IDHD-2#TRPBF 42232 16-Lead (5mm × 4mm) Plastic DFN –40°C to 85°C

LTC4223CGN-1#PBF LTC4223CGN-1#TRPBF 42231 16-Lead Plastic SSOP 0°C to 70°C

LTC4223CGN-2#PBF LTC4223CGN-2#TRPBF 42232 16-Lead Plastic SSOP 0°C to 70°C

LTC4223IGN-1#PBF LTC4223IGN-1#TRPBF 4223I1 16-Lead Plastic SSOP –40°C to 85°C

LTC4223IGN-2#PBF LTC4223IGN-2#TRPBF 4223I2 16-Lead Plastic SSOP –40°C to 85°C

Consult LTC Marketing for parts speciﬁ ed with wider operating temperature ranges. *The temperature grade is identiﬁ ed by a label on the shipping container. Consult LTC Marketing for information on non-standard lead based ﬁ nish parts.

For more information on lead free part marking, go to: http://www.linear.com/leadfree/ For more information on tape and reel speciﬁ cations, go to: http://www.linear.com/tapeandreel/

2

422312f

LTC4223-1/LTC4223-2

ELECTRICAL CHARACTERISTICS

The ● denotes the speciﬁ cations which apply over the full operating temperature range, otherwise speciﬁ cations are T

= 25°C, VCC = 3.3V, V

A

SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS

Supplies

V

DD

Input Supply Range V

CC

AUXIN 12V

IN

I

DD

Input Supply Current V

CC

AUXIN 12V

IN

V

DD(UVLO)

ΔV

DD(UVLO,

HYST)

Input Supply Undervoltage Lockout VCC Rising

V

Rising

AUXIN

V

Rising

12VIN

Input Supply Undervoltage Lockout Hysteresis

V

CC

AUXIN 12V

IN

Current Limit

ΔV

SENSE(CB)

ΔV

SENSE(ACL)

I

AUX(ACL)

Circuit Breaker Trip Sense Voltage, (V

12VIN

– V

12VSENSE

)

Active Current Limit Sense Voltage, (V

12VIN

– V

12VSENSE

)

AUXOUT Active Current Limit V

AUXOUT

= 0V

Integrated Switch

R

DS(ON)

Switch Resistance (V

– V

AUXIN

AUXOUT

)/I

AUXOUT

I

= 150mA (Note 4)

AUXOUT

Gate Drive

ΔV

GATE

I

GATE(UP)

I

GATE(DN)

I

GATE(FPD)

External N-Channel Gate Drive (V

12VGATE

– V

12VOUT

)

(Note 3)

External N-Channel Gate Pull-Up Current Gate Drive On, V

External N-Channel Gate Pull-Down Current Gate Drive Off

V

= 17V, V

12VGATE

External N-Channel Gate Fast Pull-Down Current

Fast Turn Off V

= 17V, V

12VGATE

Current Sense

G

12IMON

V

12IMON

ΔV

SENSE(MAX)

V

12IMON(CLP)

R

12IMON

V

12IMON(MIN)

12IMON Pin Gain Ratio ΔV

12IMON

/Δ(V

12VIN

– V

12VSENSE

)

(V

12IMON Pin Output Voltage (V

12IMON Pin Maximum Input Sense Voltage

12IMON Pin Clamp Voltage (V

12IMON Pin Output Resistance (V

12IMON Pin Minimum Output Voltage (V

12VIN

– V

12VSENSE

Comparator Inputs

V

PG(TH)

V

PG(HYST)

V

TMR(TH)

Power Good Threshold Voltage V

Power Good Hysteresis V

TIMER Pin Threshold Voltage V

12VOUT

V

AUXOUT

12VOUT

V

AUXOUT

TIMER

V

TIMER

Falling

Rising Falling

= 3.3V, V

AUXIN

= 0V

12VGATE

= 12V

12VOUT

= 12V

12VOUT

) = (75mV, 25mV)

) = 75mV, VCC = 2.7V

) = 150mV, VCC = 2.7V

) = 0V

=12V, unless otherwise speciﬁ ed. (Note 2)

12VIN

●

2.7

●

2.7

●

10

●

2.3

●

2.4

●

9.4

●

40

●

70

●

70

●

47.5 50 52.5 mV

●

54 60 66 mV

●

165 240 330 mA

●

4.5 6.2 7.9 V

●

–7 –10 –14 μA

●

0.5 1 2 mA

●

90 160 250 mA

●

30 33 36 V/V

●

2.25 2.475 2.7 V

●

82.5 mV

●

2.9 3.2 3.5 V

●

115 165 215 kΩ

●

10

●

2.8

●

20

●

5

●

1.198

●

0.15

0.8

0.4

0.6

2.45

2.5

9.7

110 110 110

0.3 0.5

0 130 mV

10.3

2.885

60 16

1.235

0.2

6 6

14

2 1 1

2.6

2.6 10

180 150 150

10.6

2.97

110

30

1.272

0.25

mA mA mA

mV mV mV

mV mV

V V V

Ω

V V

422312f

3

LTC4223-1/LTC4223-2

ELECTRICAL CHARACTERISTICS

The ● denotes the speciﬁ cations which apply over the full operating temperature range, otherwise speciﬁ cations are TA = 25°C, VCC = 3.3V, V

SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS

I

TMR(UP)

I

TMR(DN)

TIMER Pull-Up Current V

TIMER Pull-Down Current V

Open Drain Outputs

V

OL

V

OH

I

PU

Output Low Voltage (⎯F⎯A⎯U⎯L⎯T, ⎯1⎯2⎯P⎯G⎯O⎯O⎯D,

⎯A⎯U⎯X⎯P⎯G⎯O⎯O⎯

D)

Output High Voltage (⎯F⎯A⎯U⎯L⎯T, ⎯1⎯2⎯P⎯G⎯O⎯O⎯D,

⎯A⎯U⎯X⎯P⎯G⎯O⎯O⎯

D)

Output Pin Pull-Up Current (⎯F⎯A⎯U⎯L⎯T,

⎯1⎯2⎯P⎯G⎯O⎯O⎯

D, ⎯A⎯U⎯X⎯P⎯G⎯O⎯O⎯D)

Logic Inputs

V

IN(TH)

I

IN(LEAK)

R

PU

Logic Input Threshold (12ON, AUXON, ⎯E⎯N)

Input Leakage Current (12ON, AUXON) VIN = V

⎯E⎯

N Pin Pull-Up Resistance

Other Pin Functions

I

12VSENSE

I

12VOUT

R

OUT(DIS)

12V

OUT Pin Discharge Resistance 12V

Pin Input Current V

SENSE

Pin Input Current Gate Drive On, V

OUT

AUXOUT

Propagation Delays

t

CB

t

PHL(SENSE)

t

PHH(AUXON)

t

PHH(12ON)

t

RST(ON)

t

RST(VCC)

t

PLL(UVLO)

t

PHL(GATE)

t

PLH(PG)

t

P(12IMON)

AUX Circuit Breaker Trip Delay After Power Up

Sense Voltage, (12VIN – 12V High to 12V

GATE

Low

SENSE

)

AUXON High to AUXOUT High

12ON High to 12V

GATE

High

Input Low (12ON, AUXON) to ⎯F⎯A⎯U⎯L⎯T High

VCC Low to ⎯F⎯A⎯U⎯L⎯T High

12VIN Low to 12V

AUXIN Low to

⎯E⎯

N High to 12V

12V

Low to ⎯1⎯2⎯P⎯G⎯O⎯O⎯D High

OUT

AUXOUT Low to

Low

GATE

⎯A⎯U⎯X⎯P⎯G⎯O⎯O⎯

Low

GATE

⎯A⎯U⎯X⎯P⎯G⎯O⎯O⎯

D High

Input Sense Voltage Step to 12IMON Propagation Delay

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 the device pins are negative. All voltages are referenced to GND unless otherwise speciﬁ ed.

= 1V, Initial Timing Cycle

TIMER

V

= 0V, In AUX Fault Mode

TIMER

V

= 0V, In 12V Fault Mode

TIMER

= 2V, No Faults

TIMER

V

= 2V, In Reset Mode

TIMER

= 3mA

I

OL

(Note 5)

= 1.5V

V

PU

CC

= 12V

12VSENSE

Gate Drive Off

= 6V

V

12VOUT

V

ΔV ΔV

ΔV

AUXVOUT

SENSE SENSE

SENSE

= 2V

= 300mV, C = 100mV, C

= 100mV

= 3.3V, V

AUXIN

= 12V

12VOUT

= 10nF

12VGATE

= 10nF

12VGATE

Note 3: An internal clamp limits the 12V above 12V

. Driving this pin to voltages beyond the clamp may damage

OUT

=12V, unless otherwise speciﬁ ed. (Note 2)

12VIN

●

–7

●

–7

●

–140

●

1.3

●

2

●

VCC – 1 V

●

–6 –10 –14 μA

●

0.8 2 V

●

60 100 140 kΩ

●

10 50 100 μA

●

20 50 100 μA

●

400

●

375

●

12 25 50 μs

●

61218 μs

●

61218 μs

●

–10 –10

–200

2 8

–13 –13

–260

2.6 16

0.15 0.4 V

±1 μA

800 750

0.5

1600 1500

1

5

12

15 30 μs

30 60 μs

20 40 μs

80 150 μs

20 40 μs

26 μs

pin to a minimum of 4.5V

GATE

the device. Note 4: For the DFN package, the AUX switch on resistance, R

DS(ON)

is guaranteed by correlation to wafer test measurements. Note 5: The output pins

pull-up to V

of 10μA. However, an external pull-up resistor may be used

CC

when faster rise time is required or for V

⎯F⎯A⎯U⎯L⎯

T, ⎯1⎯2⎯P⎯G⎯O⎯O⎯D and ⎯A⎯U⎯X⎯P⎯G⎯O⎯O⎯D have an internal

voltages greater than VCC.

OH

μA μA μA

μA

mA

limit

422312f

Ω Ω

μs μs

4

LTC4223-1/LTC4223-2

TYPICAL PERFORMANCE CHARACTERISTICS

Speciﬁ cations are T

3.3V, V

=12V, unless otherwise speciﬁ ed.

12VIN

ICC vs V

1.6

CC

Supply Current vs Temperature

1.0

12IMON Gain Ratio vs Temperature

35

= 25°C, VCC = 3.3V, V

A

AUXIN

=

1.2

0.8

(mA)

CC

I

0.4

0

3.0 3.5 4.0 4.5

2.5 VCC (V)

5.0 5.5 6.0

12IMON Output Voltage vs Sense Voltage

4

3

2

1

12IMON OUTPUT VOLTAGE (V)

0

20 40 60 80

0

SENSE VOLTAGE (mV)

100 120 140

422312 G01

422312 G04

0.8

0.6

0.4

SUPPLY CURRENT (mA)

0.2

0

–50

–25

TEMPERATURE (°C)

Power-Good Threshold vs

12V

OUT

Temperature

10.4

10.3

10.2

10.1

POWER-GOOD THRESHOLD (V)

OUT

12V

10.0 –50

–25 0 25 50 75 100

TEMPERATURE (°C)

V

CC

12V

IN

AUXIN

02550

RISING

FALLING

75 100

422312 G02

422312 G05

34

33

32

12IMON GAIN RATIO (V/V)

31

–50

–25 0 25 50 70 100

TEMPERATURE (°C)

AUXOUT Power-Good Threshold vs Temperature

2.92

2.90

2.88

2.86

AUXOUT POWER-GOOD THRESHOLD (V)

2.84 –50

–25 0 25 50 75 100

RISING

FALLING

TEMPERATURE (°C)

422312 G03

422312 G06

Circuit Breaker Trip Voltage vs Temperature

52

51

50

49

CIRCUIT BREAKER TRIP VOLTAGE (mV)

48

–50

–25 0 25 50 75 100

TEMPERATURE (°C)

422312 G07

Active Current Limit Sense Voltage vs Temperature

62

61

60

59

ACTIVE CURRENT LIMIT SENSE VOLTAGE (mV)

58

–50

–25 0 25 50 75 100

TEMPERATURE (°C)

422312 G08

AUX Active Current Limit vs Temperature

250

240

230

220

210

AUX ACTIVE CURRENT LIMIT (mA)

200

–50

02550

–25

TEMPERATURE (°C)

75 100

422312 G09

422312f

5

LTC4223-1/LTC4223-2

TYPICAL PERFORMANCE CHARACTERISTICS

Speciﬁ cations are TA = 25°C, VCC = 3.3V, V

3.3V, V

0.5

0.4

0.3

=12V, unless otherwise speciﬁ ed.

12VIN

AUX Switch On Resistance vs Temperature Gate Drive vs Temperature Gate Drive vs I

) (V)

GATE

6.3

6.2

6.1

) (V)

GATE

7

6

5

4

3

GATE

AUXIN

=

0.2

AUX SWITCH-ON RESISTANCE (Ω)

0.1 –50

–25 0 25 50 75 100

TEMPERATURE (°C)

Gate Pull-Up Current vs Temperature

–11.0

–10.5

–10.0

–9.5

GATE PULL-UP CURRENT (µA)

–9.0

–50

–25 0 25 50 75 100

TEMPERATURE (°C)

422312 G10

422312 G13

6.0

GATE DRIVE (ΔV

5.9 –50

–25 0 25 50 75 100

TEMPERATURE (°C)

AUX Circuit Breaker Trip Delay vs Temperature

30

25

20

AUX CIRCUIT BREAKER TRIP DELAY (µs)

15

–50

02550

–25

TEMPERATURE (°C)

422312 G11

75 100

422312 G14

2

GATE DRIVE (ΔV

1

0

–2 –4

–6 –10

I

(μA)

GATE

Active Current Limit Delay vs Sense Voltage

100

10

1

0.1

ACTIVE CURRENT LIMIT DELAY (µs)

0.01 50 150 200 250

100

SENSE VOLTAGE (mV)

–8 –12

422312 G12

300

422312 G15

Gate Fast Pull-Down Current vs Temperature

250

200

150

100

GATE FAST PULL-DOWN CURRENT (mA)

50

–50

–25 0 25 50 75 100

TEMPERATURE (°C)

6

422312 G16

Output Discharge Resistance vs Temperature Logic Input Threshold vs V

OUTPUT DISCHARGE RESISTANCE (Ω)

1200

1000

800

600

400

200

–50

02550

–25

TEMPERATURE (°C)

12V

OUT

AUXOUT

75 100

422312 G17

3.0

2.5

2.0

1.5

1.0

LOGIC INPUT THRESHOLD (V)

0.5

0

2.5

3.0 3.5

4.0 5.0 VCC (V)

CC

HIGH

LOW

4.5 5.5 6.0

422312 G18

422312f

PIN FUNCTIONS

LTC4223-1/LTC4223-2

12V

(Pin 1): 12V Current Sense Input. Connect this

SENSE

pin to the output of the current sense resistor. The electronic circuit breaker trips if the voltage across the sense resistor exceeds 50mV for more than a fault ﬁ lter delay.

(Pin 2): 12V Supply Input. Undervoltage lockout

12V

IN

disables the 12V supply until the input at 12V

exceeds

IN

9.7V.

12IMON (Pin 3): 12V Current Sense Monitoring Output. This pin monitors the sense voltage between 12V 12V

. The gain ratio between this pin’s voltage and

SENSE

IN

and

the sense voltage is 33.

12ON (Pin 4): 12V Supply On Control Digital Input. A ris-

⎯E⎯

ing edge turns on the external N-channel MOSFET if

N is pulled low and a falling edge turns it off. A high-to-low transition on this pin will clear the 12V supply faults.

AUXIN (Pin 5): Auxiliary Supply Input. An internal 0.3Ω switch is connected between AUXIN and AUXOUT pins. Undervoltage lockout holds the switch off until the input at AUXIN exceeds 2.5V.

(Pin 6): Bias Supply Input. This pin provides power

V

CC

to the device’s internal circuitry and operates from 2.7V to 6V. Undervoltage lockout circuit disables the device until the input at V

exceeds 2.45V. Bypass with 330nF.

CC

AUXON (Pin 7): Auxiliary Supply On Control Digital Input.

⎯E⎯

A rising edge turns on the internal switch if

N is pulled low and a falling edge turns it off. A high-to-low transition on both this pin and 12ON pin will clear the auxiliary supply faults.

GND (Pin 8): Device Ground.

TIMER (Pin 9): Timer Capacitor Terminal. Connect a

capacitor between this pin and ground to set a 741ms/μF duration for initial timing cycle, 123ms/μF for AUX current limit during power-up and 6ms/μF duration for 12V current limit before the external MOSFET is turned off.

⎯E⎯

N (Pin 10): Enable Input Intended for Card Presence

Detect. Ground this pin to enable the external N-channel MOSFET and internal switch to turn on. If this pin is pulled high, the switches are not allowed to turn on. An internal 100k resistor pulls up this pin. A high-to-low transition will clear faults.

⎯A⎯U⎯X⎯P⎯G⎯O⎯O⎯

D (Pin 11): Auxiliary Supply Power Status

Output. Open drain output that is normally pulled high by an internal 10μA current source or an external pull-up resistor to V

. It pulls low when the AUXOUT pin voltage

CC

exceeds the power-good threshold of 2.901V.

AUXOUT (Pin 12): Auxiliary Supply Output. This pin is the output from the internal switch connected between AUXIN and AUXOUT pins. It signals

⎯A⎯U⎯X⎯P⎯G⎯O⎯O⎯

D low when

it exceeds 2.901V. A 750Ω active pull-down discharges AUXOUT to ground when the internal switch is turned off.

⎯F⎯A⎯U⎯L⎯

T (Pin 13): Auxiliary and 12V Supply Fault Status

Output. Open drain output that is normally pulled high by an internal 10μA current source or an external pull-up resistor

. It pulls low when the circuit breaker is tripped due

to V

CC

to an overcurrent fault on auxiliary or 12V supply.

⎯1⎯2⎯P⎯G⎯O⎯O⎯

D (Pin 14): 12V Supply Power Status Output.

Open drain output that is normally pulled high by an internal 10μA current source or an external pull-up resistor

. It pulls low when the 12V

to V

CC

pin voltage exceeds

OUT

the power-good threshold of 10.36V.

12V

(Pin 15): 12V Gate Drive Return and Power-Good

OUT

Input. Connect this pin to the source of the external Nchannel MOSFET for gate drive return. This pin signals

⎯1⎯2⎯P⎯G⎯O⎯O⎯

MOSFET is turned off, 12V

D low when it exceeds 10.36V. When the external

is discharged to ground

OUT

through a 800Ω active pull-down.

12V

(Pin 16): Gate Drive for 12V Supply External N-

GATE

Channel MOSFET. An internal 10μA current source charges the gate of the external N-channel MOSFET. An internal clamp limits the gate voltage to 6.2V above 12V

OUT

. A resistor and capacitor network from this pin to ground sets the turn-on rate and compensates the active current limit. During turn-off, a 1mA pull-down current discharges 12V lockout, a 160mA pull-down current between 12V 12V

to ground. During short circuit or undervoltage

GATE

is activated.

OUT

GATE

and

Exposed Pad (Pin 17, DHD Package): Exposed pad may be left open or connected to device ground.

422312f

7

LTC4223-1/LTC4223-2

FUNCTIONAL DIAGRAM

CHARGE

PUMP

12V

IN

12V

SENSE

12ON 12V FET ON

60mV

+

50mV

+

–

R

IN

5k

10μA

ACL

+ –

ECB

+

1mA

A1

+ –

R

OUT

165k

6.2V

GATE

DRIVER

12IMON

12V

GATE

12V

OUT

–

10μA

PG2

+

10.3V

–

12PGOOD

12V SUPPLY

CONTROL

12V PWRGD

V

CC

V

CC

2μA

R2

UVLO3

+

12V

IN

9.7V

–

UVLO2

+

2.45V

VCCV

CC

10μA

AUXIN

2.5V

0.2V

–

+ –

+

UVLO1

CP2

–

CP1

+

1.235V

–

EN CARD PRESENCE

V

CC

200μA

TIMER

AUXON AUX FET ON

GND

SYSTEM

CONTROL

AUX SUPPLY

CONTROL

12V FAULT

AUX FAULT

V

CC

10μA

FAULT

V

CC

10μA

AUXPGOOD

8

AUXIN

THERMAL

SHUTDOWN

MFETRSNS

AUX PWRGD

10μA

PG1

CHARGE

PUMP

+

2.885V

–

AUXOUT

422312 FD

422312f

LINEAR TECHNOLOGY LTC4223-1, LTC4223-2 Technical data

Specifications and Main Features

Frequently Asked Questions

User Manual