Detailed Description

The MAX4826–MAX4831 are forward-/reverse-current-

limited switches that operate from a +2.3V to +5.5V

input voltage range and guarantee a 50mA and 100mA

minimum current-limit threshold for different options.

The voltage drop across an internal sense resistor is

compared to two reference voltages to indicate a for-

ward- or reverse-current-limit fault. When the load cur-

rent exceeds the preset current limit for greater than

the fault-blanking time, the switch opens.

The MAX4827/MAX4829/MAX4831 have an autoretry

function that turns on the switch again after an internal

retry time expires. If the faulty load condition is still pre-

sent after the blanking time, the switch turns off again

and the cycle is repeated. If the faulty load condition is

not present, the switch remains on.

The MAX4826/MAX4828/MAX4830 do not have the

autoretry option, and the switch remains in latchoff mode

until ON or the input power is cycled from high to low

and then high again.

The undervoltage lockout (UVLO) circuit prevents erro-

neous switch operation when the input voltage goes too

low during startup conditions.

Reverse-Current Protection

switch is shut off and FFLG is asserted if the reverse-

current-limit condition persists for more than the blank-

ing time. This feature prevents excessive reverse cur-

rents from flowing through the device.

Switch-On/Off Control

Toggle ON high to enable the current-limited switches.

the UVLO threshold (typically 2V) and there is no fault.

When a forward-/reverse-current fault is present or the

die exceeds the thermal-shutdown temperature of

+150°C, OUT is internally disconnected from IN, and

the supply current decreases to 8µA (latchoff). The

switch is now operating in one of its off states. The

switch off state also occurs when driving ON low, thus

reducing the supply current (shutdown) to 0.01µA.

Table 1 illustrates the ON/OFF state of the MAX4826–

MAX4831 current-limit switches.

50mA/100mA Current-Limit Switches with

NO-LOAD Flag in µDFN

6

_______________________________________________________________________________________

Pin Description

PIN

NAME

FUNCTION

1

IN

Input. Bypass IN with a 0.1µF ceramic capacitor to ground.

2

GND

Ground

3

OUT

Switch Output. Bypass OUT with a 0.1µF capacitor to ground

4

FFLG

Current-Limit Fault Output. FFLG is an open-drain output. FFLG goes low when the device stays in

forward- or reverse-current limit for more than the blanking time period. FFLG is high impedance

when a fault is not present or when ON is low.

5

NOLD

No-Load Flag Output. NOLD is an open-drain output. NOLD goes low when a load of less than 10mA

(MAX4826–MAX4829) or 5mA (MAX4830/MAX4831) is delivered to the output. NOLD is high

impedance when a fault is not present or when ON is low.

6

ON

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

ON

FAULT

SWITCH ON/OFF

SUPPLY CURRENT MODE

Low

X

OFF

Shutdown

High

Undervoltage lockout

OFF

Latchoff

High

Thermal

Latchoff

Latchoff

High

Current limit

MAX4827/MAX4829/MAX4831. Cycle repeats until fault is

removed.

See the Autoretry (MAX4827/

MAX4829/MAX4831) section

Table 1. MAX4826–MAX4831 Switch Truth Table