50mA to 600mA Programmable

Current-Limit Switches

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Detailed Description

The MAX4995A/MAX4995AF/MAX4995AL/MAX4995B/

MAX4995C programmable current-limit switches oper-

ate from +1.7V to +5.5V and provide internal current

limiting adjustable from 50mA to 600mA. These devices

feature a fixed blanking time and a FLAG output that

notifies the processor when a fault condition is present.

Programmable Current Limit

A resistor from SETI to GND programs the current limit

for the switch (see the

Setting the Current Limit sec-

tion). If the output current exceeds the current limit for a

asserts and the MAX4995A/MAX4995AF/MAX4995AL

enter the autoretry mode. The MAX4995B latches off

the switch, and the MAX4995C enters the continuous

current-limit mode.

Autoretry (MAX4995A/MAX4995AF/

MAX4995AL)

When the forward current reaches the current-limit

FLAG asserts if the overcurrent-limit condition is pre-

after the blanking time has elapsed and during that

switch turns on again. If the fault still exists, the cycle

repeats. If the fault has been removed, the switch stays

on. During this cycle, FLAG stays low. In autoretry if

the thermal power rating of the package is exceeded,

the MAX4995A/MAX4995AF/MAX4995AL go into ther-

mal shutdown.

The autoretry feature saves system power in case of an

time when the switch is on, the supply current is held at

off, the current through the switch is zero. Thus, the

average output current is much less than the pro-

grammed current limit. Calculate the average output

current using the following equation:

524ms, the duty cycle is 3%, resulting in a 97% power

savings over the switch being on the entire time.

Latchoff (MAX4995B)

When the forward current reaches the current-limit

FLAG asserts if an overcurrent-limit condition is present

elapsed. The switch turns off if the overcurrent condition

Pin Description

PIN (UTQFN)

MAX4995AL

MAX4995_

NAME

FUNCTION

1, 10

1, 10

IN

Power Input. Bypass IN with a 1µF ceramic capacitor to ground. Use higher capacitance

to prevent large load transients from pulling down the supply voltage if necessary.

Connect both power inputs (IN) together.

22

FLAG

Open-Drain, Overload Indicator Output.

FLAG goes low when the overload fault duration

exceeds the blanking time, reverse current is detected, thermal shutdown mode is

active, or SETI is connected to ground.

3—

ON

Active-Low, Switch-On Input. Drive

ON low to turn on the switch.

—

3

ON

Active-High, Switch-On Input. Drive ON high to turn on the switch.

4

4

GND

Ground

5

5

SETI

Overload Current Limit Adjust. Connect a resistor from SETI to ground to program the

overcurrent limit. Do not connect any capacitance larger than 20pF to SETI.

6, 9

6, 9

N.C.

No Connect. Not internally connected.

7, 8

7, 8

OUT

Switch Output. Bypass OUT with a 1µF capacitor to ground. Connect both outputs (OUT)

together.