FS98O02B-PCE datasheet(29/50 Pages) FORTUNE

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FS98O02

Rev.1.5

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16.3 ADC Control Register

There are some ADC control related registers in FS98O02. There will be some more detail descriptions

about using the ADC control register to get the proper ADC operation in users’ applications.

Table 16-1: ADC Control Related Registers

Address

Name

Bit 7

Bit 6

Bit 5

Bit 4

Bit 3

Bit 2

Bit 1

Bit 0

Reset State

WDT Reset State

06h

INTF

ADIF

---0 --00

07h

INTE

GIE

ADIE

0--0 --00

10h

ADOH

ADO [23:16]

0000 0000

11h

ADOM

ADO [15:8]

0000 0000

12h

ADOL

ADO [7:0]

0000 0000

13h

ADCON

ADRST

ADM [2:0]

---- 0000

2Fh

NETG

ADG [1:0]

ADEN

---- 0000

IN+

IN-

VRH

VRL

{ADOH, ADOM, ADOL}

VIH

VIL

MUX

Modulator

Digital

Comb

Filter

ADG [1:0]

ADRST

ADEN

Figure 16-1: the Block Diagram of ADC

The ADC contains a ΔΣ modulator and a digital comb filter. When ADEN = 1, the ΔΣ modulator (ADC) will

be enabled. When ADEN = 0, the ΔΣ modulator (ADC) will be disabled. When ADRST = 1, the digital comb filter

will be enabled. When ADRST = 0, the digital comb filter will be reset.

16.3.1

ADC Output Rate and Settling Time

The ΔΣ ADC is generally an over-sampling ADC. The ADC’s each digital output code is the result of

sampling the input signal N times and processed by DSP. The ADC’s sampling frequency is decided by ADCF.

ADM decides when to send out a 16-bit digital code after sampling N times, and raises an interrupt signal

every time the ADC produces a digital output code. In fact, the ADC’s each digital output code is the result from

the previous 2*N times sampling results. If any of the ADC’s input, reference voltage, ADG or AZ is switched,

the first two output codes are normally not stable, and the third output code and later codes are stable for

calculation.

The ADC’s output rate is selected by ADM [2:0] as described in Table 16-2.

Table 16-2: ADC Output Rate

ADM [2:0]

ADC Output Rate

000

ADCF/125 (~320Hz for 1MHz MCK or ~1.28kHz for 4MHz MCK)

001

ADCF/250 (~160Hz for 1MHz MCK or ~640Hz for 4MHz MCK)

FS98O02B-PCE Datasheet(PDF) 29 Page - Fortune Semiconductor Corp.

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