Datasheet

153

7734Q–AVR–02/12

AT90PWM81/161

13.5.2.2 Two Ramp Mode

In Two Ramp mode, the whole cycle is divided in two moments:

• One moment for PSCr0 description with OT0 which gives the time of the whole moment

• One moment for PSCr1 description with OT1 which gives the time of the whole moment

Figure 13-5. PSCr0 & PSCr1 basic waveforms in Two Ramp mode.

PSCOUTr0 and PSCOUTr1 signals are defined by On-Time 0, Dead-Time 0, On-Time 1 and

Dead-Time 1 values with:

On-Time 0 = (OCRrRAH/L - OCRrSAH/L) × 1/Fclkpsc

On-Time 1 = (OCRrRBH/L - OCRrSBH/L) × 1/Fclkpsc

Dead-Time 0 = (OCRrSAH/L + 1) × 1/Fclkpsc

Dead-Time 1 = (OCRrSBH/L + 1) × 1/Fclkpsc

Note: Minimal value for Dead-Time 0 and Dead-Time 1 = 1/Fclkpsc.

13.5.2.3 One Ramp Mode

In One Ramp mode, PSCOUTr0 and PSCOUTr1 outputs can overlap each other.

On-Time 0 On-Time 1

PSCOUTn0

PSCOUTn1

Dead-Time 1

Dead-Time 0

PSC Cycle

OCRnRB

OCRnSB

OCRnRA

OCRnSA

PSC Counter