DS786A1

19

CS4412A

4.5

Device Protection and Error Reporting

The CS4412A has built-in protection circuitry for over-current, under-voltage, and thermal warning/over-

load conditions. The levels of the over-current error, thermal error, and VP under-voltage trigger points

are listed in the PWM Power Output Characteristics table on page 6. Automatic shut-down will occur

whenever any of these preset thresholds other than thermal warning are crossed.

Each error and warning pin implements an active-low open-drain driver and requires an external 22 k

Ω

pull-up resistor for proper operation.

4.5.1

Over-Current Protection

An over-current error condition will occur if the peak output current exceeds the Over-Current Error trigger

point. Over-current errors for OUT1/2 and OUT3/4 are reported on the ERROC12 and ERROC34 pins

respectively. The power output of the channel which is reporting the over-current condition will be set to

high-impedance until the error condition has been removed and the reset signal for that channel has been

toggled from low to high.

4.5.2

Thermal Warning, Thermal Error, and Under-Voltage Error

Table 8 shows the behavior of the TWR and ERRUVTE pins. When the junction temperature exceeds the

junction thermal warning trigger point, the TWR pin will be set low. If the junction temperature continues

to increase beyond the junction thermal error trigger point, the ERRUVTE pin will be set low. If the voltage

on VP falls below the VP under-voltage error trigger point, ERRUVTE will be set low.

When the thermal error or VP under-voltage trigger point is crossed, all power outputs will be set in a high-

impedance state until the error condition has been removed and both the RST12 and RST34 signals have

been toggled from low to high.

ERROCxy

Reported Condition

0

Over-current error on channel x or channel y.

1

Operating current of channel x and y within allowable limits.

Table 7. Over-current Error Conditions

TWR

ERRUVTE

Reported Condition

0

0

Thermal warning and thermal error and/or under-voltage error.

0

1

Thermal warning only.

1

0

Under-voltage error.

1

1

Junction temperature and VP voltage within normal limits.

Table 8. Thermal and Under-Voltage Error Conditions