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MAX1694EUB

USB Current-Limited Switches with Fault Blanking

Maxim Integrated 

USB Current-Limited Switches

with Fault Blanking

PIN

1, 3, 9

2, 4, 8, 10

5

6

7

NAME

IN

OUT

ON (ON)

GND

FAULT

Pin Description

FUNCTION

Input. P-channel MOSFET source. Connect all IN pins together and bypass with a 1µF

ceramic capacitor to ground.

Switch Output. P-channel MOSFET drain. Connect all OUT pins together and bypass with a

0.1µF capacitor to ground.

Active-Low (High) Switch On Input. A logic low (high) turns the switch on.

Ground

Fault-Indicator Output. This open-drain output goes low when the device is in thermal shut-

down, undervoltage lockout, or on a sustained (>10ms) current-limit condition. For the

MAX1694 only, this output latches low when asserted, and the power switch is turned off

until the latch is reset.

IN

FAULT

N

ON

(ON)

P

OUT

MAX1693

P

(MAX1693H)

REPLICA

AMPLIFIER

ON

P

ON

10ms

TIMER

HOT

CURRENT-LIMIT

AMPLIFIER

1.24V

GND

CONTROL

CIRCUITRY

Figure 1. MAX1693 Functional Diagram

_______________Detailed Description

The MAX1693/(MAX1693H)/MAX1694 P-channel MOS-

FET power switches limit output current to 0.7A min to

1.0A max. When the output current is increased

beyond the current limit (ILIMIT), the current also

increases through the replica switch (IOUT/6500). The

current-limit error amplifier compares the voltage to the

internal 1.24V reference and regulates the current back

to the ILIMIT.

These switches are not bidirectional; therefore, the

input voltage must be higher than the output voltage.

Continuous Short-Circuit Protection

The MAX1693/(MAX1693H)/MAX1694 are foldback

short circuit-protected switches. In the event of an out-

put short-circuit or current-overload condition, the cur-

rent through the switch is foldback-current limited to

500mA continuous for the MAX1693. For the MAX1694,

if the short circuit lasts longer than 10ms, the switch is

latched off.

Thermal Shutdown

The MAX1693/(MAX1693H)/MAX1694 feature thermal

shutdown. The switch turns off and the FAULT output

goes low immediately (no fault blanking) when the junc-

tion temperature exceeds +165°C. The MAX1694

remains latched with the switch off and the FAULT out-

put low. When the MAX1693/(MAX1693H) cools 20°C,

the switch turns back on. If the fault short-circuit condi-

tion is not removed, the switch will cycle on and off,

resulting in a pulsed output.

FAULT Indicator

The MAX1693/(MAX1693H)/MAX1694 provide a fault

output (FAULT). A 100kΩ pullup resistor from FAULT to

IN provides a logic control signal. This open-drain out-

put goes low when any of the following conditions

occur:

• The input voltage is below the undervoltage-lockout

(UVLO) threshold.

• The die temperature exceeds the thermal shutdown

temperature limit of +165°C.

• The device is in current limit and the 10ms fault-

blanking period is exceeded.

_______________________________________________________________________________________ 7

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