VIPER11 datasheet(27/37 Pages) STMICROELECTRONICS

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DS11873 Rev 5

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VIPer11

General description

5.16

Auto-restart

When a fault occurs, the PWM is disabled in auto-restart until the fault is removed.

This means that:

PWM stops switching for a restart time, namely:

 tRESTART (1 sec, typ.), in case the fault is one of the following: overload/short-circuit, max.

duty cycle counter, VCC clamp, overtemperature.

 tDIS_RESTART (0.5 sec, typ.), in case the fault is triggered at the DIS pin (input/output

overvoltage).

At the end of restart time:

– if the fault is still present, the protection is tripped in the same way after a debounce

time (see Figure 34), namely:

 tSS + tOVL (8 + 50msec, typ.) in case the fault is overload/short-circuit;

 tclamp_max (0.5 msec, typ.) in case the fault is VCC clamp;

 tDIS (1 msec, typ) in case the fault is triggered at the DIS pin (input/output overvoltage);

 10 switching cycles in case the fault is max. duty cycle counter;

 1 switching cycle in case the fault is overtemperature;

– if the fault is no longer present, normal operation is restored, as shown in Figure 34.

During restart time, the HV generator is activated periodically, maintaining the VCC pin

voltage between VCSon and VCCon.

Figure 34. Protection timing diagram with auto-restart option

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