A8603KESTR-R datasheet(31/42 Pages) ALLEGRO

31 / 42 page

Multiple-Output Regulator for

Automotive LCD Displays

A8603

Allegro MicroSystems, LLC

115 Northeast Cutoff

Worcester, Massachusetts 01615-0036 U.S.A.

1.508.853.5000; www.allegromicro.com

Fault Monitoring

The fault monitoring system prioritizes the fault in three different

categories. Based on the severity of the fault, diagnostic algo-

rithm handle the shutdown sequence of all regulators.

FAULT1 (GROUP1)

If any fault from the below list is detected, the A8603 halts

operation and pulls the FAULT pin low. All regulators shut down

in sequence. It then attempts to restart operation after a delay,

tRESTART (default 100 ms). Internally, there is a fault counter that

keeps tracks of how many times any fault has occurred. If the

fault counter reaches its programmed limit (default 8), the A8603

is completely shutdown. A hardware reset (either by EN = L or

VIN below UVLO) is then required before the A8603 can restart.

Startup Fail

Regulator output voltage fails to reach 90% of its

target voltage within timeout period

Regulator

Undervoltage

Regulator output voltages are below 80% of the

target voltage. This signal is ignored during startup.

Regulator

Overvoltage

Regulator output voltage are above 120% of the

target voltage. This signal is ignored during startup.

Regulator

Overcurrent

Regulator output currents are above the current limit

threshold. This signal is ignored during startup.

FSET Shorted FSET pin shorted to ground. IC moves to internal

fixed 1 MHz oscillator.

• Each regulator output is protected by its own independent

overcurrent limit. When an output current exceeds its limit,

the corresponding regulator goes in to overcurrent protection

mode to protect itself from damage. If the overcurrent

condition persists for 50 ms, all regulators are turned off

following the normal shutdown sequence.

• Each regulator output is protected by its own overvoltage

fault detection. When an output voltage exceeds its limit, the

corresponding regulator is turned off immediately. The other

outputs then shut down following normal sequence. The same

applies to undervoltage fault detection.

• When FSET pin is shorted to ground, IC begins a shutdown

sequence, at the switching frequency set by the internal 1 MHz

oscillator. The FAULT pin is pulled low and the internal error

counter is increased by 1.

FAULT2 (GROUP2)

When following faults are detected, the A8603 halts operation

and pulls the FAULT pin low. All outputs are shut off immedi-

ately. It then attempts to restart operation after a delay, tRESTART

(default 100 ms). Internally, there is a fault counter that keeps

tracks of how many times any fault has occurred. If the fault

counter reaches its programmed limit (default 8), the A8603 is

completely shut down. A hardware reset (either by EN = L or VIN

below UVLO) is then required before the A8603 can restart.

SW Overvoltage SW pin voltage exceeds SWOVP

SW Overcurrent SW pin current exceeds ISWILIM2.

Thermal

Shutdown

IC die temperature exceeds TTSD

FAULT3 (GROUP3)

When a supply undervoltage fault is detected, the A8603 shuts

down immediately. All outputs are turned off without following

the shutdown sequence. All digital states are erased. The FAULT

flag will not be asserted. The device will not attempt to restart.

VIN UVLO

VIN (input supply) is below 2.8 V.

BIAS UVLO

VBIAS (internal rail) is below 2.6 V.

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