CS5451A

DS635F3

3

1.

PIN DESCRIPTION

Clock Generator

Master Clock Input

25

XIN - External clock signal or oscillator input.

Control Pins and Serial Data I/O

Serial Clock Output

1

SCLK - Serial port clock signal that determines the output data rate for SDO pin. Rate of SCLK is

dependent on the XIN frequency and state of OWRS pin.

Serial Data Output

2

SDO -Serial port data output pin. Data will be output at a rate defined by SCLK.

Frame Sync

3

FSO - Framing signal indicates when data samples are about to be transmitted on the SDO pin.

Serial Port Enable

4

SE - When SE is low, the output pins of the serial port are tri-stated.

Current Input Gain

5

GAIN - A logic high sets current channel gain to 1, a logic low sets the gain to 20. If no connection

is made to this pin, it will default to logic low level (through internal 200 k

Ω resistor to DGND).

Output Word Rate Select

23

OWRS - A logic low sets the output word rate (OWR) to XIN/2048 (Hz). A logic high sets the

OWR to XIN/1024 (Hz). If no connection is made to this pin, then OWRS will default to logic low

level (through internal 200 k

Ω resistor to DGND).

Reset

24

RESET - Low activates Reset, all internal registers are set to their default states.

Analog Inputs/Outputs

Voltage Reference Input

7

VREFIN - The input to this pin establishes the voltage reference for the on-chip modulator.

Voltage Reference Output

8

VREFOUT - The on-chip voltage reference output. The voltage reference has a nominal magni-

tude of 1.2 V and is referenced to the AGND pin on the converter.

Differential Voltage Inputs

11,12

18,17

22,21

VIN3+, VIN3- - Differential analog input pins for the voltage channel 3.

VIN2+, VIN2- - Differential analog input pins for the voltage channel 2.

VIN1+, VIN1- - Differential analog input pins for the voltage channel 1.

Differential Current Inputs

13,14

16,15

20,19

IIN3+, IIN3- - Differential analog input pins for the current channel 3.

IIN2+, IIN2- - Differential analog input pins for the current channel 2.

IIN1+, IIN1- - Differential analog input pins for the current channel 1.

Power Supply Connections

Analog Ground

6

AGND - Analog ground.

Positive Analog Supply

9

VA+ - The positive analog supply. Typical +3 V ±10% relative to AGND.

Negative Analog Supply

10

VA- - The negative analog supply. Typical -2 V ±10% relative to AGND.

Charge Pump Drive

26

CPD - Designed to drive external charge pump circuitry that will produce a negative analog sup-

ply (VA-)voltage.

Digital Ground

27

DGND - Digital Ground.

Positive Digital Supply

28

VD+ - The positive digital supply. Typical +3 V ±10% relative to AGND.

1

14

7

13

6

12

5

11

9

4

3

8

10

2

15

18

16

24

20

19

25

21

17

26

27

22

28

23

IIN2-

VIN2+

IIN2+

RESET

IIN1+

IIN1-

XIN

VIN1-

VIN2-

CPD

DGND

VIN1+

VD+

OWRS

IIN3-

VIN3+

IIN3+

GAIN

VA+

VA -

SE

VREFOUT

VIN3-

FSO

SDO

VREFIN

SCLK

AGND

Differential Current Input 2

Differential Voltage Input 2

Differential Current Input 2

Reset

Differential Current Input 1

Differential Current Input 1

Master Clock

Differential Voltage Input 1

Differential Voltage Input 2

Charge Pump Drive

Digital Ground

Differential Voltage Input 1

Digital Supply

Output Word Rate Select

Differential Current Input 3

Differential Voltage Input 3

Differential Current Input 3

Current Input Gain

Positive Analog Supply

Negative Analog Supply

Serial Port Enable

Reference Output

Differential Voltage Input 3

Frame Sync

Serial Data Output

Reference Input

Serial Clock Output

Analog Ground