CS5566

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DS806PP2

5/4/09

4. PIN DESCRIPTIONS

CS – Chip Select, Pin 1

The Chip Select pin allows an external device to access the serial port. If SMODE = VL (SSC

Mode) and CS is held high, the SDO output and the SCLK output will be held in a

high-impedance output state.

TST – Factory Test, Pin 2

Factory test only. Connect to VLR.

SMODE – Serial Mode Select, Pin 3

The serial interface mode pin (SMODE) dictates whether the serial port behaves as a master or

slave interface. If SMODE is tied high (to VL), the port will operate in the Synchronous

Self-Clocking (SSC) mode. In SSC mode, the port acts as a master in which the converter out-

puts both the SDO and SCLK signals. If SMODE is tied low (to VLR), the port will operate in the

Synchronous External Clocking (SEC) mode. In SEC mode, the port acts as a slave in which

the external logic or microcontroller generates the SCLK used to output the conversion data

word from the SDO pin.

AIN+, AIN- – Differential Analog Input, Pin 4, 5

AIN+ and AIN- are differential inputs for the converter.

V1- – Negative Power 1, Pin 6

The V1- and V2- pins provide a negative supply voltage to the core circuitry of the chip. These

two pins should be decoupled as shown in the application block diagrams. V1- and V2- should

be supplied from the same source voltage. For single-supply operation, these two voltages are

nominally 0 V (Ground). For dual-supply operation, they are nominally -2.5 V.

V1+ – Positive Power 1, Pin 7

The V1+ and V2+ pins provide a positive supply voltage to the core circuitry of the chip. These

two pins should be decoupled as shown in the application block diagrams. V1+ and V2+ should

be supplied from the same source voltage. For single supply-operation, these two voltages are

nominally +5 V. For dual-supply operation, they are nominally +2.5 V.

BUFEN – Buffer Enable, Pin 8

Buffers on input pins AIN+ and AIN- are enabled if BUFEN is connected to V1+ and disabled if

connected to V1-.

VREF+, VREF- – Voltage Reference Input, Pin 9, 10

A differential voltage reference input on these pins functions as the voltage reference for the

converter. The voltage between these pins can range between 2.4 volts and 4.2 volts, with

4.096 volts being the nominal reference voltage value.

SLEEP

12

Sleep Mode Select

BP/UP

11

Bipolar/Unipolar Select

VREF-

10

Voltage Reference Input

VREF+

9

Voltage Reference Input

BUFEN

8

Buffer Enable

V1+

7

Positive Power 1

V1-

6

Negative Power 1

AIN-

5

Differential Analog Input

AIN+

4

Differential Analog Input

3

2

CS

1

Chip Select

RST

13

Reset

VLR2

14

Logic Interface Return

CONV

15

Convert

DCR

16

Digital Core Regulator

V2+

17

Positive Voltage 2

V2-

18

Negative Voltage 2

MCLK

19

Master Clock

VLR

20

Logic Interface Return

VL

21

Logic Interface Power

SDO

22

Serial Data Output

SCLK

23

Serial Clock Input/Output

RDY

24

Ready

TST

Factory Test

SMODE

Serial Mode Select