Preliminary Technical Data

Rev. PrA 15-Nov-04| Page 11 of 27

PIN CONFIGURATION AND FUNCTION DESCRIPTIONS

AD5744/64

TOP VIEW

(Not to Scale)

SYNC

SCLK

SDIN

SDO

CLR

LDAC

D1

D0

AGNDA

VOUTA

VOUTB

AGNDB

AGNDC

VOUTC

VOUTD

AGNDD

1

32

25

916

8

24

17

PIN 1

INDICATOR

Figure 6. 32-Lead TQFP Pin Configuration Diagram

Table 5. Pin Function Descriptions

Pin No.

Mnemonic

Function

1

SYNC

Active Low Input. This is the frame synchronization signal for the serial interface.

While SYNC is low, data is transferred in on the falling edge of SCLK.

2

Serial Clock Input. Data is clocked into the shift register on the falling edge of SCLK.

This operates at clock speeds up to 30 MHz.

3

Serial Data Input. Data must be valid on the falling edge of SCLK.

4

SDO

Serial Data Output. Used to clock data from the serial register in daisy-chain or

readback mode.

5

Active Low Input. Asserting this pin sets the DAC registers to 0x0000.

6

LDAC

Load DAC. Logic input. This is used to update the DAC registers and consequently

the analog output. When tied permanently low, the addressed DAC register is

write cycle, the DAC input register is updated but the output is held off until the

falling edge of LDAC. In this mode, all analog outputs can be updated

simultaneously on the falling edge of LDAC.

7, 8

D0, D1

D0 and D1 form a digital I/O port. The user can configure these pins as inputs or

outputs that are configurable and readable over the serial interface. When

9

RSTOUT

Reset Logic Output. This is the output from the on-chip voltage monitor used in the

reset circuit. If desired, it may be used to control other system components.

10

RSTIN

Reset Logic Input. This input allows external access to the internal reset logic.

Applying a Logic 0 to this input resets the DAC output to 0 V. In normal operation,

RSTIN should be tied to Logic 1.

11

DGND

Digital GND Pin.

12

Digital Supply Pin. Voltage ranges from 2.7 V to 5.5 V. When programmed as

13, 31

Positive Analog Supply Pins. Voltage ranges from 11.4 V to 16.5 V.

14

PGND

Ground Reference Point for Analog Circuitry.

15, 30

Negative Analog Supply Pins. Voltage ranges from –11.4 V to –16.5 V.

AD5744/AD5764