Rainbow-electronics T89C5115 Bedienungsanleitung PDF herunterladen (Seite 80)

T89C5115

4128A–8051–04/02

Table 54. Selected Analog Input

Voltage Conversion When the ADCIN is equals to VAREF the ADC converts the signal to 3FFh (full scale). If

the input voltage equals VAGND, the ADC converts it to 000h. Input voltage between

VAREF and VAGND are a straight-line linear conversion. All other voltages will result in

3FFh if greater than VAREF and 000h if less than VAGND.

Note that ADCIN should not exceed VAREF absolute maximum range! (see section

“AC-DC”)

Clock Selection The ADC clock is the same as CPU.

The maximum clock frequency for ADC is 700 KHz. A prescaler is featured (ADCCLK)

to generate the ADC clock from the oscillator frequency.

Figure 38. A/D Converter Clock

ADC Standby Mode When the ADC is not used, it is possible to set it in standby mode by clearing bit ADEN

in ADCON register. In this mode its power dissipation is about 1 uW.

SCH2 SCH1 SCH0 Selected Analog input

000AN0

001AN1

010AN2

011AN3

100AN4

101AN5

110AN6

111AN7

Prescaler ADCLK

A/D

Converter

ADC Clock

CPU

CLOCK

CPU Core Clock Symbol

÷ 2

1 2 ... 75 76 77 78 79 80 81 82 83 84 85 ... 104 105

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Rainbow-electronics T89C5115 Bedienungsanleitung Seite 80