HI-7159A データシートの表示（PDF） - Intersil

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HI-7159A

Microprocessor-Compatible, 5-1/2 Digit A/D Converter

Intersil 

HI-7159A

TABLE 7. REQUEST BYTE FORMAT, SERIAL MODE 2 (SENT TO HI-7159A)

(RESERVED)

BYTE REQUEST

REQUEST BIT

D7

D6

D5

D4

D3

D2

D1

D0

0

0

0

0

Digit 0

0

0

0

1

Digit 1

0

0

1

Digit 2

0

1

0

Digit 3

0

1

1

Digit 4

1

0

0

Digit 5

1

0

1

Converter Status

1

1

0

CONVERTER

(†)

UPDATE STATUS

D7

D6

0 No Update

0

Updated

1

(† = Reserved)

TABLE 8. STATUS BYTE FORMAT (RECEIVED FROM HI-7159A)

(†)

CONTINUITY

RESOLUTION

CONVERSION TYPE

PARITY

ERROR

D5

0 Single

Continuous

D4

0 51/2

1 41/2

D3

1 Comp

0 Uncomp

Error

D2

D1

D0

1

1 No

0

1

0 Yes

1

0

1

TABLE 9. DIGIT BYTE FORMAT, PARALLEL AND SERIAL MODE 1 (RECEIVED FROM HI-7159A)

DIGIT BYTE

D7

D6

D5

D4

D3

D2

D1

Digit Pair 0, 1

MSB1

LSB1

MSB0

Digit Pair 2, 3

MSB3

LSB3

MSB2

Digit Pair 4, 5

Polarity

(1 = POS)

Overrange

(1 = OR)

MSB5

LSB5

MSB4

D0

LSB0

LSB2

LSB4

TABLE 10. DIGIT BYTE FORMAT, SERIAL MODE 2 (RECEIVED FROM HI-7159A)

DIGIT BYTE

D7

D6

D5

D4

D3

D2

D1

D0

Digits 0 - 4

0

0

1

1

MSB

LSB

Digit 5

0

0

1

1

Polarity

Overrange

MSB

LSB

(1 = POS)

(1 = OR)

Single Conversion Mode

The suggested algorithm for reading the HI-7159A in its

single conversion mode of operation is shown in Figure 5.

Essentially it consists of initiating a conversion, waiting until

the conversion is complete, and then reading the results.

Since no further conversions take place, the data may be

read out at any time and at any speed. This is the most

straightforward method of reading the HI-7159A.

Continuous Conversion Mode

Once a command byte is sent to the HI-7159A initiating the

continuous conversion mode, the output data registers will be

updated continuously after every conversion. This makes

obtaining a valid reading more difficult, since the possibility

exists that the current data could be overwritten by a new

conversion before all the digit bytes are read. To prevent this,

the status byte should be read before and after the data is

read from the converter, to ensure that the converter has not

updated during the reads. This is demonstrated in Figure 6.

9

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