LTC4211CS8 datasheet(11/36 Pages) LINER

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LTC4211

4211f

PI FU CTIO S (8-Lead Package/10-Lead Package)

FAULT (Not available on S8/MS8, Pin 10 MS): FAULT is

both an input and an output. Connected to this pin are an

analog comparator (COMP6) and an open-drain N-chan-

nel FET. During normal operation, if COMP6 is driven

below 1.236V, the electronic circuit breaker trips and the

GATE pin pulls low. Typically, a 10k pull-up resistor

connects to the FAULT pin. This allows the LTC4211 to

begin a second timing cycle (VFAULT > 1.286) and start-up

properly. This also allows the use of the FAULT pin as a

status output. Under normal operating conditions, the

FAULT output is a logic high. Two conditions cause an

active low on FAULT: (1) the LTC4211’s electronic circuit

breaker trips because of an output short circuit (VOUT =

0V) or because of a fast output overcurrent transient

(FAST COMP trips circuit breaker); or (2) VFILTER >

1.236V. The FAULT output is driven to logic low and is

latched logic low until the ON pin is driven to logic low for

150

µs (the tRESET duration).

FILTER (Not available S8/MS8, Pin 3 MS): Overcurrent

Fault Timing Pin and Overvoltage Fault Set pin. With a

capacitor connected from this pin to ground, the SLOW

COMP’s response time can be adjusted. In the S8/MS8

version of the LTC4211, the FILTER pin is not available and

the delay time from overcurrent detect to GATE OFF is fixed

at 20

µs.

VREF

–

SLOW

COMP

50mV

150mV

0.2V

COMP7

GLITCH FILTER

(SEE NOTE 1)

UVLO

–

FAST

COMP

300ns

DELAY

GLITCH FILTER

150

µs

GLITCH FILTER

FUNCTION OF

OVERDRIVE

VREF

0.2V

TRIPS

OR UVLO

ON LOW

START-UP

CURRENT

REGULATOR

GATE

CHARGING

200

µA10µA

POWER BAD

CB TRIPS

VREF

µA

6 (7)

GATE

7 (8)

SENSE

8 (9)

VCC

CHARGE

PUMP

VZ (TYP) = 12V

GND

4 (5)

FAULT

(10)

MS ONLY

–

COMP1

5 (6)

4211 BD

COMP2

–

COMP3

tTIMER

0.2V

VREF

COMP4

–

VREF

COMP5

NORMAL, RESET

NOTE 1: SET BY FILTER CAPACITOR FOR MS

µs DEFAULT FOR MS8, S8

PIN NUMBERS FOR S8/MS8 (MS)

NORMAL

FAULT

TIMER

3 (4)

FILTER

(3)

MS ONLY

µA

VCC

µA

VCC

µA

LOGIC

RESET

COMP6

VZ (TYP) = 26V

VCC

BLOCK DIAGRA

LTC4211CS8 Datasheet(PDF) 11 Page - Linear Technology

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