ADS8342

SBAS277 – MAY 2003

www.ti.com

9

Terminal Functions

TERMINAL

TYPE(1)

NAME

NO.

DESCRIPTION

Analog Input Signals

AIN0

45

AI

Analog input 0

AIN1

46

AI

Analog input 1

AIN2

47

AI

Analog input 2

AIN3

48

AI

Analog input 3

COMMON

44

AI

Analog input common signal

REFIN

41

AI

Reference voltage input pin for external reference voltage. Decouple to reference ground with a 0.1

µF

ceramic capacitor.

REFGND

42

AI

Reference ground. Connected to the ground of the external reference voltage.

Digital Interface Signals

A(x)

5, 6

DI

Address decode input, select analog input.

DB(x)

16–23,

26–33

DO

Output 3-state data bus. DB15 (MSB) to DB0 (LSB). Data lines are 3-state during conversion.

RD should be asserted only when the part is not converting.

CS

10

DI

Active low chip select signal

RD

9

DI

Active low read signal

CLK

11

DI

System clock

CLKDIV(x)

3, 4

DI

Select clock divider ratio. Internally divides external clock (pin 11) by 1, 2, 4, or 8.

CONV

8

DI

Convert start. When CONV switches from high to low, the device switches from sample mode to hold

mode, independent of the external clock status. The address for the next conversion will be latched on

low-to-high transition.

BUSY

15

DO

BUSY goes high during a conversion and returns low at the end when data is available for reading.

BYTE

7

DI

Active high bus width is 8 bits. When BYTE is low, the bus width is 16 bits.

Power Supply

+AVDD

39

P

Positive analog power supply, +5VDC. Decouple to analog ground with a 0.1µF ceramic capacitor and a

4.7

µF tantalum capacitor. Referenced to the same power supply as +DVDD (pin 12).

–AVDD

37

P

Negative analog power supply –5VDC. Decouple to analog ground with a 0.1µF ceramic capacitor and

a 4.7

µF tantalum capacitor. Referenced to the same power supply as –DVDD (pin 14).

BVDD

24

P

Digital I/O power supply in the range 2.7V to DVDD. Decouple to digital I/O ground with a 0.1µF

ceramic capacitor and a 4.7

µF tantalum capacitor.

+DVDD

12

P

Positive digital power supply +5VDC. Decouple to digital ground with a 0.1µF ceramic capacitor and a

4.7

µF tantalum capacitor. Referenced to the same power supply as +AVDD (pin 39).

–DVDD

14

P

Negative digital power supply –5VDC. Decouple to digital ground with a 0.1µF ceramic capacitor and a

4.7

µF tantalum capacitor. Referenced to the same power supply as –AVDD (pin 37).

AGND

36, 38

P

Analog ground. Connected directly to digital ground (pin 13) and digital I/O ground (pin 25).

BGND

25

P

Digital I/O ground. Connected directly to analog ground (pins 36 and 38) and digital ground (pin 13).

DGND

13

P

Digital ground. Connected directly to analog ground (pins 36 and 38) and digital I/O ground (pin 25).

(1) AI is analog input, AO is analog output, DI is digital input, DO is digital output, and P is power-supply connection.