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ADS8556, ADS8557, ADS8558

SBAS404D – OCTOBER 2006 – REVISED FEBRUARY 2016

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Product Folder Links: ADS8556 ADS8557 ADS8558

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(1)

AI = analog input; AIO = analog input/output; DI = digital input; DO = digital output; DIO = digital input/output; and P = power supply.

Pin Functions

PIN

DESCRIPTION

NAME

NO.

PARALLEL INTERFACE (PAR/SER = 0)

SERIAL INTERFACE (PAR/SER = 1)

1

DIO, DI

Data bit 14 input/output

Output is '0' for the ADS8557, ADS8558

Hardware mode (HW/SW = 0):

Reference buffers enable input.

When low, all reference buffers are enabled

(mandatory if internal reference is used). When

high, all reference buffers are disabled.

Software mode (HW/SW = 1):

Connect to BGND or BVDD.

The reference buffers are controlled by bit C24

(REFBUF) in control register (CR).

DB13/SDI

2

DIO, DI

Data bit 13 input/output

Output is MSB for the ADS8557

and '0' for the ADS8558

Hardware mode (HW/SW = 0):

Connect to BGND

Software mode (HW/SW = 1):

Serial data input

DB12

3

DIO

Data bit 12 input/output

Output is '0' for the ADS8558

Connect to BGND

DB11

4

DIO

Data bit 11 input/output

Output is MSB for the ADS8558

Connect to BGND

DB10/SDO_C

5

DIO, DO

Data bit 10 input/output

When SEL_C = 1, data output for channel C

When SEL_C = 0, tie this pin to BGND

DB9/SDO_B

6

DIO, DO

Data bit 9 input/output

When SEL_B = 1, data output for channel B

When SEL_B = 0, tie this pin to BGND

When SEL_C = 0, data from channel C1 are

also available on this output

DB8/SDO_A

7

DIO, DO

Data bit 8 input/output

Data output for channel A

When SEL_C = 0, data from channel C0 are

also available on this output

When SEL_C = 0 and SEL_B = 0, SDO_A acts

as the single data output for all channels

BGND

8

P

Buffer IO ground, connect to digital ground plane

BVDD

9

P

Buffer IO supply, connect to digital supply (2.7 V to 5.5 V). Decouple with a 1-

μF ceramic

capacitor or a combination of 100-nF and 10-

μF ceramic capacitors to BGND.

10

DIO, DI,

DI

Word mode (WORD/BYTE = 0): Data bit 7

input/output

Daisy-chain enable input.

When high, DB[5:3] serve as daisy-chain inputs

DCIN[A:C]. If daisy-chain mode is not used,

connect to BGND.

Byte mode (WORD/BYTE = 1):

High byte enable input.

When high, the high byte is output first on

DB[15:8]. When low, the low byte is output first

on DB[15:8].

DB6/SCLK

11

DIO, DI

Word mode (WORD/BYTE = 0):

Data bit 6 input/output

Serial interface clock input (36 MHz, max)

Byte mode (WORD/BYTE = 1):

Connect to BGND or BVDD

DB5/DCIN_A

12

DIO, DI

Word mode (WORD/BYTE = 0):

Data bit 5 input/output

channel A.

Byte mode (WORD/BYTE = 1):

Connect to BGND or BVDD

DB4/DCIN_B

13

DIO, DI

Word mode (WORD/BYTE = 0):

Data bit 4 input/output

daisy-chain data input for channel B.

Byte mode (WORD/BYTE = 1):

Connect to BGND or BVDD

DB3/DCIN_C

14

DIO, DI

Word mode (WORD/BYTE = 0):

Data bit 3 input/output

daisy-chain data input for channel C.

Byte mode (WORD/BYTE = 1):

Connect to BGND or BVDD