REV. B

–4–

AD7896

PIN FUNCTION DESCRIPTION

Pin

Pin

No.

Mnemonic

Description

Positive supply voltage, +2.7 V to 5.5 V.

3

AGND

Analog Ground. Ground reference for track/hold, comparator and DAC.

4

SCLK

Serial Clock Input. An external serial clock is applied to this input to obtain serial data from

the AD7896. A new serial data bit is clocked out on the falling edge of this serial clock. Data

is guaranteed valid for 10 ns after this falling edge so data can be accepted on the falling edge

when a fast serial clock is used. The serial clock input should be taken low at the end of the

serial data transmission.

5

SDATA

Serial Data Output. Serial data from the AD7896 is provided at this output. The serial data

is clocked out by the falling edge of SCLK, but the data can also be read on the falling edge

of the SCLK. This is possible because data bit N is valid for a specified time after the falling

edge of the SCLK (data hold time) and can be read before data bit N+1 becomes valid a

specified time after the falling edge of SCLK (data access time) (see Figure 4). Sixteen bits

of serial data are provided with four leading zeros followed by the 12 bits of conversion data.

On the sixteenth falling edge of SCLK, the SDATA line is held for the data hold time and

then disabled (three-stated). Output data coding is straight binary.

6

DGND

Digital Ground. Ground reference for digital circuitry.

7

CONVST

Convert Start. Edge-triggered logic input. On the falling edge of this input, the track/hold

goes into its hold mode and conversion is initiated. If CONVST is low at the end of conver-

sion, the part goes into power down mode. In this case, the rising edge of CONVST

“wakes up” the part.

8

BUSY

The BUSY pin is used to indicate when the part is doing a conversion. The BUSY pin will go

high on the falling edge of CONVST and will return low when the conversion is complete.

PIN CONFIGURATION

1

2

3

4

8

7

6

5

TOP VIEW

(Not to Scale)

AD7896

SDATA

DGND

CONVST

BUSY

AGND

SCLK

ORDERING GUIDE

Temperature

Linearity

SNR

Package

Model

Range

Error (LSB)

(dB)

Option*

AD7896AN

–40

°C to +85°C

±1 LSB

70 dB

N-8

AD7896BN

–40

°C to +85°C

±1/2 LSB

70 dB

N-8

AD7896AR

–40

°C to +85°C

±1 LSB

70 dB

SO-8

AD7896BR

–40

°C to +85°C

±1/2 LSB

70 dB

SO-8

AD7896JR

0

°C to +70°C

±1 LSB

70 dB

SO-8

AD7896SQ

–55

°C to +125°C

±1 LSB

70 dB

Q-8

*N = Plastic DIP; Q = Cerdip; SO = SOIC.