Specifications

Section 43. High-Speed PWM

High-Speed PWM

Example 43-28: PWM Output Override Control

43.12.2 Override Priority

When the PENH bit (IOCONx<15>) and the PENL bit (IOCONx<14>) are set, the following

priorities apply to the PWM output:

1. If a fault is active, the FLTDAT<1:0> bits (IOCONx<5:4>) override all other potential

sources and set the PWM outputs.

2. If a fault is not active, but a current-limit event is active, the CLDAT<1:0> bits

(IOCONx<3:2>) are selected as the source to set the PWM outputs.

3. If neither a fault nor a current-limit event is active, and a user Override Enable bit is set to

OVRENH and OVRENL, the associated OVRDAT<1:0> bits (IOCONx<7:6>) set the PWM

output.

4. If no override conditions are active, the PWM signals generated by the time base and duty

cycle comparator logic are the sources that set the PWM outputs.

43.12.3 Override Synchronization

If the OSYNC bit (IOCONx<0>) is set, the output overrides performed by the OVRENH bit

(IOCONx<9>), OVRENL bit (IOCONx<8>) and OVRDAT<1:0> bits (IOCONx<7:6>) bits are

synchronized to the PWM time base. Synchronous output overrides occur when the time base is

zero. If PTEN = 0, meaning the PWM timer is not running, writes to IOCONx take effect on the

next T

CY boundary.

43.12.4 Fault/Current-Limit Override and Dead Time Logic

In the event of a Fault and Current-Limit condition, the data in the FLTDAT<1:0>

bits (IOCONx<5:4>) or CLDAT<1:0> bits (IOCONx<3:2>) determine the state of the PWM I/O

pins.

If any of the FLTDAT<1:0> bits (IOCONx<5:4>) or CLDAT<1:0> bits (IOCONx<3:2>) are ‘0’, the

PWMxH and/or PWMxL outputs are driven inactive immediately, bypassing the dead time logic.

This behavior turns off the PWM outputs immediately without any additional delays. This can aid

many power conversion applications that require a fast response to fault shutdown signals to limit

circuitry damage and control system accuracy.

If any of the FLTDAT<1:0> bits (IOCONx<5:4>) or CLDAT<1:0> bits (IOCONx<3:2>) are ‘1’, the

PWMxH and/or PWMxL outputs are driven active immediately passing through the dead time

logic and, therefore, are delayed by the specified dead time value. In this case, dead time is

inserted even if a Fault or Current-Limit condition occurs.

/* Define override state of the PWM outputs. PWMxH and PWMxL outputs will be

at logic level ‘0’when overridden. */

IOCON1bits.OVRDAT = 0;

/* Override PWMxH and PWMxL outputs */

IOCON1bits.OVRENH = 1;

__builtin_nop();

IOCON1bits.OVRENL = 1;

/* Clear overrides of PWMxH and PWMxL outputs */

IOCON1bits.OVRENH = 0;

__builtin_nop();

IOCON1bits.OVRENL = 0;