Maxim MAX4370ESA Datasheet

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General Description

The MAX4370 is a circuit-breaker IC designed to offer
protection in hot-swap applications using Maxim’s
DualSpeed/BiLevel™ detection. This controller,
designed to reside either on the backplane or on the
removable card, is used to protect a system from start­up damage when a card or board is inserted into a rack
with the main system power supply turned on. The
card’s discharged filter capacitors provide a low
impedance that can momentarily cause the main power
supply to collapse. The MAX4370 prevents this start-up
condition by providing inrush current regulation during
a programmable start-up period, allowing the system to
stabilize safely. In addition, two on-chip comparators
provide DualSpeed/BiLevel short-circuit protection and
overcurrent protection during normal operation.

The MAX4370 provides protection for a +3V to +12V
single supply. An internal charge pump generates the
controlled gate drive for an external N-channel MOS­FET power switch. The MAX4370 latches the switch off
after a fault condition until an external reset signal
clears the device. Other features include a status pin to
indicate a fault condition, an adjustable overcurrent
response time, and a power-on reset comparator.

The MAX4370 is specified for the extended-industrial
temperature range (-40°C to +85°C) and is available in
an 8-pin SO package.

Applications

Hot Board Insertion
Solid-State Circuit Breaker

Features

♦ DualSpeed/BiLevel Protection During Normal

Operation

♦ Inrush Current Regulated at Start-Up
♦ Resides Either on the Backplane or on the

Removable Card

♦ Programmable Start-Up Period and Response

Time

♦ Allows Safe Board Insertion and Removal from

Live Backplane

♦ Protection for +3V to +12V Single Supplies
♦ Latched Off After Fault Condition
♦ Status Output Pin
♦ Internal Charge Pump Generates Gate Drive for

External N-Channel MOSFET

MAX4370

†

Current-Regulating Hot-Swap Controller with

DualSpeed/BiLevel Fault Protection

________________________________________________________________

Maxim Integrated Products

1

N

M1

MAX4370

V

OUT

C

BOARD

CTIM

C

TIM

CSPD

C

SPD

ON

ON

GND

STAT

V

CC

R

SENSE

STAT

REMOVABLE CARDBACKPLANE

V

IN

VSEN GATE

GND

Typical Operating Circuit

19-1472; Rev 0; 4/99

PART

MAX4370ESA -40°C to +85°C

TEMP. RANGE PIN-PACKAGE

8 SO

Ordering Information

DualSpeed/BiLevel is a trademark of Maxim Integrated Products.

†

Patent Pending

Pin Configuration appears at end of data sheet.

MAX4370

Current-Regulating Hot-Swap Controller with
DualSpeed/BiLevel Fault Protection

2 _______________________________________________________________________________________

ABSOLUTE MAXIMUM RATINGS

ELECTRICAL CHARACTERISTICS

(VIN= +2.7V to +13.2V, TA= -40°C to +85°C, unless otherwise noted. Typical values are at VIN= +5V and TA= +25°C.) (Note 2)

Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional
operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to
absolute maximum rating conditions for extended periods may affect device reliability.

Note 1: ON can be pulled below ground. Limiting the current to 2mA ensures that this pin is never lower than about -0.8V.

V

IN

to GND...........................................................................+15V

STAT to GND..........................................................-0.3V to +14V

GATE to GND ..............................................-0.3V to (V

IN

+ 8.5V)

ON to GND (Note 1)................................................. -1V to +14V

CSPD to GND.............-0.3V to the lower of (V

IN

+ 0.3V) or +12V

VSEN, CTIM to GND....................................-0.3V to (V

IN

+ 0.3V)

Current into ON...................................................................±2mA

Current into Any Other Pin................................................±50mA

Continuous Power Dissipation (T

A

= +70°C)

SO (derate 5.9mW/°C above +70°C)........................... 471mW

Operating Temperature Range ...........................-40°C to +85°C

Storage Temperature Range.............................-65°C to +150°C

Lead Temperature (soldering, 10sec)............................ +300°C

Start-up is initiated only if V

GATE

is less than this

voltage

ON = V

IN

I

GATE

= 8.5µA, measured above V

IN

Measured with respect to VIN; voltage at which
internal clamp circuitry is triggered

During start-up (current regulation provided by
fast comparator)

Time from current overload to V

GATE

< 0.1V,

C

GATE

= 1000pF to GND (triggered by the fast

comparator during normal operation)

VSEN = V

IN

V

GATE

= VIN(Note 4)

CTIM = floating

10mV overdrive, from overload condition to GATE
discharging

VIN- VSEN

VIN- V

SEN

CSPD = floating

100nF on CTIM

100nF on CSPD to GND

CONDITIONS

V0.1Gate Overvoltage Threshold

V

2.7

5

Minimum Gate Drive Voltage

V6.7 7.5Maximum Gate Voltage

80

Gate Discharge Current

µs60t

OFF

Turn-Off Time

µA100I

GATE

Gate Charge Current

µs5.5

ms21 31 41

t

START

Start-Up Period
(Note 3)

mA0.6 1I

Q

Supply Current

V2.7 13.2V

IN

Input Voltage Range

µA0.2 10I

B,VSEN

VSEN Input Bias Current

ns460t

FCD

Fast Comparator Response
Time

mV180 200 220V

FC,TH

Fast Comparator Threshold

mV

45 50 55

V

SC,TH

Slow Comparator
Threshold

µs10 20 40

t

CSPD

Slow Comparator Response
Time

ms10 20 40

UNITSMIN TYP MAXSYMBOLPARAMETER

During turn-off, triggered by a fault in normal
operation or ON falling edge

µA

75 225 550

I

GATE,DIS

POWER SUPPLIES

MOSFET DRIVER

CURRENT CONTROL

VIN≥ 5V
VIN≥ 2.7V

TA= +25°C
TA= T

MIN

to T

MAX

43.5 56

MAX4370

Current-Regulating Hot-Swap Controller with

DualSpeed/BiLevel Fault Protection

_______________________________________________________________________________________ 3

ELECTRICAL CHARACTERISTICS (continued)

(VIN= +2.7V to +13.2V, TA= -40°C to +85°C, unless otherwise noted. Typical values are at VIN= +5V and TA= +25°C.) (Note 2)

Note 2: All devices are 100% tested at T

A

= +25°C. All temperature limits are guaranteed by design.

Note 3: The start-up period (t

START

) is the time during which the slow comparator is ignored and the device acts as a current limiter

by regulating the sense current with the fast comparator. It is measured from ON rising above 0.6V to STAT rising.

Note 4: The current available at GATE is a function of V

GATE

(see Typical

Operating Characteristics.

)

VIN= 5V, rising threshold

CONDITIONS

mV3V

HYST

Hysteresis

V0.575 0.6 0.625V

TH,ON

Threshold Voltage

UNITSMIN TYP MAXSYMBOLPARAMETER

2.7V ≤ VIN≤ 13.2V mV/V0.1 1PSRR

Power-Supply Rejection
Ratio

Input can be driven to the absolute maximum
limit without false output inversion

V-0.1 13.2

10mV overdrive

V

ON

Input Voltage Range

µs10t

D,COMP

Propagation Delay

µA0.001 1I

B,ON

Input Bias Current

To restart after a fault µs20t

RESTART

ON Pulse Width Low

V

STAT

≤ +13.2V µA1Output Leakage Current

I

SINK

= 1mA V0.4V

OL

Output Voltage Low

Start-up is initiated when this threshold is
reached at V

IN

V2.25 2.67V

UVLO

Threshold

mV100V

UVLO,HYST

Hysteresis

Time which input voltage must exceed under­voltage lockout before start-up is initiated

ms100 150 200t

D,UVLO

UVLO to Start-Up Delay

DIGITAL OUTPUT (STAT)

ON COMPARATOR

VINUNDERVOLTAGE LOCKOUT

MAX4370

Current-Regulating Hot-Swap Controller with
DualSpeed/BiLevel Fault Protection

4 _______________________________________________________________________________________

Typical Operating Characteristics

(Circuit of Figure 7, VIN= 5V, R

SENSE

= 100mΩ, M1 = FDS6670A, C

BOARD

= 470µF, C

GATE

= 0, RS= 0, TA= +25°C, unless other-

wise noted.)

0

0.3

0.2

0.1

0.5

0.4

0.9

0.8

0.7

0.6

1.0

02468101214

SUPPLY CURRENT vs. INPUT VOLTAGE

MAX4370 toc01

VIN (V)

SUPPLY CURRENT (mA)

ON = V

IN

I

GATE

= 10µA

ON = GND

-40 -15 10 35 60 85

SUPPLY CURRENT vs. TEMPERATURE

MAX4370 toc02

TEMPERATURE (°C)

0

0.3

0.2

0.1

0.5

0.4

0.9

0.8

0.7

0.6

1.0

SUPPLY CURRENT (mA)

ON = V

IN

VIN = 12V

VIN = 5V

VIN = 3V

49.0

49.6

49.4

49.2

50.0

49.8

50.8

50.6

50.4

50.2

51.0

02468101214

SLOW COMPARATOR THRESHOLD

vs. INPUT VOLTAGE

MAX4370 toc03

VIN (V)

V

SC, TH

(mV)

TA = -40°C

TA = +25°C

TA = +85°C

0

200

100

400

300

600

500

700

1 10 100 1000

FAST COMPARATOR RESPONSE TIME

vs. OVERDRIVE VOLTAGE

MAX4370 toc07

VOD (mV)

t

FCD

(ns)

VIN = 3V

VIN = 5V

VIN = 12V

18

20

19

22

21

23

24

18

20

19

22

21

23

24

0682 4 10 12 14

SLOW COMPARATOR

RESPONSE TIME vs. INPUT VOLTAGE

MAX4370 toc05

VIN (V)

t

CSPD

(µs)

t

CSPD

(ms)

CSPD = 110nF
TIME IN ms

CSPD = 0
TIME IN µs

190

196
194
192

200
198

108
206
204
202

210

FAST COMPARATOR THRESHOLD

vs. INPUT VOLTAGE

MAX4370 toc06

V

FC, TH

(mV)

02468101214

V

IN

(V)

TA = -40°C

TA = +25°C

TA = +85°C

400

430
420
410

450
440

490
480
470
460

500

-40 -20 0 20 40 60 80 100

FAST COMPARATOR RESPONSE TIME

vs. TEMPERATURE

MAX4370 toc08

TEMPERATURE (°C)

t

FCD

(ns)

VIN = 12V

VIN = 3V

VOD = 10mV

VIN = 5V

250

270

310

290

330

350

042 6 8101214

START-UP TIME

vs. INPUT VOLTAGE

MAX4370 toc09

VIN (V)

t

START

(µs)

25

27

31

29

33

35

t

START

(ms)

C

TIM

= 100nF

TIME IN ms

C

TIM

= 1nF

TIME IN µs

MAX4370

Current-Regulating Hot-Swap Controller with

DualSpeed/BiLevel Fault Protection

_______________________________________________________________________________________

5

0

60

40

20

80

100

120

0862 4 10 12 14 16 18 20

GATE CHARGE CURRENT

vs. GATE VOLTAGE

MAX4370 toc10

V

GATE

(V)

I

GATE

(µA)

VIN = 12V

VIN = 5.0V

VIN = 3.0V

0

50

25

100

75

125

150

-40 -10 35-15 60 85

GATE CHARGE CURRENT

vs. TEMPERATURE

MAX4370 toc11

TEMPERATURE (°C)

I

GATE

(µA)

VIN = 12V

V

GATE

= 0

VIN = 5V

VIN = 3V

0

5

15

10

20

25

042 6 8101214

GATE VOLTAGE vs. INPUT VOLTAGE

MAX4370 toc12

VIN (V)

V

GATE

(V)

I

GATE

= 10µA

TA = +85°C

TA = +25°C

TA = -40°C

0

100

50

150

300

350

250
200

400

0 468102 1214161820

GATE DISCHARGE CURRENT

vs. GATE VOLTAGE

MAX4370 toc13

V

GATE

(V)

I

GATE

(µA)

VIN = 12V

VIN = 3V

TRIGGERED BY A FAULT
OR BY ON FALLING

VIN = 5V

C

BOARD

= 0, R

SENSE

= 100mΩ,

C

TIM

= 10nF, C

GATE

= 0

V

OUT

(2V/div)

V

GATE

(2V/div)

ON

100µs/div

START-UP TIME (C

BOARD

= 0)

MAX4370-16

0

100

50

200
150

350
300
250

400

-40 10-15 35 60 85

GATE DISCHARGE CURRENT

vs. TEMPERATURE

MAX4370 toc14

TEMPERATURE (°C)

I

GATE

(µA)

VIN = 3V

VIN = 5V & 12V

V

GATE

= V

IN

TRIGGERED BY A FAULT
OR BY ON FALLING

C

BOARD

= 470µF, R

SENSE

= 100mΩ,

C

TIM

= 10nF, C

GATE

= 0

I

LOAD

(1A/div)

V

OUT

(2V/div)

V

GATE

(2V/div)

ON

500µs/div

START-UP TIME (C

BOARD

= 470µF)

MAX4370-15

C

BOARD

= 470µF, R

SENSE

= 100mΩ,

C

GATE

= 22nF, C

TIM

= 10nF, RS = 0

I

LOAD

(1A/div)

V

OUT

(2V/div)

V

GATE

(2V/div)

ON

1ms/div

START-UP TIME

(EXTERNAL C

GATE

= 22nF, C

BOARD

= 470µF)

MAX4370-17

C

BOARD

= 470µF, R

SENSE

= 100mΩ,

C

GATE

= 0

I

LOAD

(1A/div)

V

OUT

(2V/div)

V

GATE

(2V/div)

0A

50µs/div

TURN-OFF TIME (C

BOARD

= 470µF)

MAX4370-18

ON

0V

Typical Operating Characteristics (continued)

(Circuit of Figure 7, VIN= 5V, R

SENSE

= 100mΩ, M1 = FDS6670A, C

BOARD

= 470µF, C

GATE

= 0, RS= 0, TA= +25°C, unless other-

wise noted.)