AT90PWM2B-16SU 查看數據表（PDF） - Atmel Corporation

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AT90PWM2B-16SU

8-bit Atmel Microcontroller with 8K Bytes In-System Programmable Flash

Atmel Corporation 

AT90PWM2/3/2B/3B

16.5.2

Running Mode Description

Waveforms and length of output signals are determined by Time Parameters (DT0, OT0, DT1,

OT1) and by the running mode. Four modes are possible :

– Four Ramp mode

– Two Ramp mode

– One Ramp mode

– Center Aligned mode

16.5.2.1

Four Ramp Mode

In Four Ramp mode, each time in a cycle has its own definition

Figure 16-6. PSCn0 & PSCn1 Basic Waveforms in Four Ramp mode

PSC Counter

OCRnSA

OCRnRA

OCRnSB

OCRnRB

0

0

On-Time 0

On-Time 1

PSCOUTn0

PSCOUTn1

Dead-Time 0

PSC Cycle

Dead-Time 1

16.5.2.2

The input clock of PSC is given by CLKPSC.

PSCOUTn0 and PSCOUTn1 signals are defined by On-Time 0, Dead-Time 0, On-Time 1 and

Dead-Time 1 values with :

On-Time 0 = OCRnRAH/L * 1/Fclkpsc

On-Time 1 = OCRnRBH/L * 1/Fclkpsc

Dead-Time 0 = (OCRnSAH/L + 2) * 1/Fclkpsc

Dead-Time 1 = (OCRnSBH/L + 2) * 1/Fclkpsc

Note: Minimal value for Dead-Time 0 and Dead-Time 1 = 2 * 1/Fclkpsc

Two Ramp Mode

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

One moment for PSCn0 description with OT0 which gives the time of the whole moment

One moment for PSCn1 description with OT1 which gives the time of the whole moment

4317K–AVR–03/2013

137

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