AT90PWM2 datasheet(349/361 Pages) ATMEL

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349

4317J–AVR–08/10

AT90PWM2/3/2B/3B

5. PSC: Output Polarity in Centered Mode

In centered mode, PSCOUTn1 outputs are not inverted, so they are active at the same time

as PSCOUTn0.

Workaround:

Use an external inverter (or a driver with inverting output) to drive the load on

PSCOUTn1.

6. PSC : POACnA/B Output Activity

These register bits are not implemented in rev A.

Workaround:

Do not use this feature.

7. VREF

Remark: To have Internal Vref on AREF pin select an internal analog feature such as DAC

or ADC.

Some stand by power consuption may be observed if Vref equals AVcc

8. DALI

Some troubles on Dali extension when edges are not symmetric.

Workaround:

Use an optocoupler providing symmetric edges on Rx and Tx DALI lines (only recom-

manded for software validation purpose).

9. DAC: Register Update

Registers DACL & DACH are not written when the DAC is not enabled.

Workaround:

Enable DAC with DAEN before writing in DACL & DACH. To prevent an unwanted zero out-

put on DAC pin, enable DAC output, with DAOE afterwards.

10. DAC : Output spikes

During transition between two codes, a spike may appears

Work around:

Filter spike or wait for steady state

No spike appears if the 4 last signifiant bits remain zero.

11. DAC driver: Output Voltage linearity

The voltage linearity of the DAC driver is limited when the DAC output goes above Vcc - 1V.

Work around:

Do not use AVcc as Vref ; internal Vref gives good results

12. ADC : Conversion accuracy

The conversion accuracy degrades when the ADC clock is 1 & 2 MHz.

Work around:

When a 10 bit conversion accuracy is required, use an ADC clock of 500 kHz or below.

13. Analog comparator: Offset value

The offset value increases when the common mode voltage is above Vcc - 1.5V.

Work around:

Limit common mode voltage

14. Analog comparator: Output signal

AT90PWM2 Datasheet(PDF) 349 Page - ATMEL Corporation

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