Data Sheet

AD5780

Rev. C | Page 9 of 28

PIN CONFIGURATION AND FUNCTION DESCRIPTIONS

2

1

3

4

5

6

7

18

19

17

16

15

14

13

LDAC

CLR

RESET

SCLK

SYNC

DGND

AGND

NOTES

1. DNC = DO NOT CONNECT. DO NOT CONNECT TO THIS PIN.

A VOLTAGE IN THE RANGE OF –16.5 V TO –2.5 V

TO AGND. THE PADDLE CAN BE LEFT ELECTRICALLY

UNCONNECTED PROVIDED THAT A SUPPLY

CONNECTION IS MADE AT THE VSS PINS. IT IS

RECOMMENDED THAT THE PADDLE BE THERMALLY

CONNECTED TO A COPPER PLANE FOR ENHANCED

THERMAL PERFORMANCE.

AD5780

TOP VIEW

(Not to Scale)

Figure 5. Pin Configuration

Table 5. Pin Function Descriptions

Pin No.

Mnemonic

Description

1

Analog Output Voltage.

2

3, 5

decoupled to AGND.

4

RESET

Active Low Reset. Asserting this pin returns the AD5780 to its power-on status.

6

CLR

Active Low Input. Asserting this pin sets the DAC register to a user defined value (see

Table 12) and updates the DAC

output. The output value depends on the DAC register coding that is being used, either binary or twos complement.

7

LDAC

Active Low Load DAC Logic Input. This pin is used to update the DAC register and, consequently, the analog output.

When tied permanently low, the output is updated on the rising edge of SYNC. If LDAC is held high during the write cycle,

the input register is updated, but the output update is held off until the falling edge of LDAC. Do not leave the LDAC pin

unconnected.

8

9

Digital Interface Supply. Digital threshold levels are referenced to the voltage applied to this pin. Voltage range is from

1.71 V to 5.5 V.

10, 21,

22, 23

DNC

Do Not Connect. Do not connect to these pins.

11

SDO

Serial Data Output.

12

SDIN

Serial Data Input. This device has a 24-bit input shift register. Data is clocked into the register on the falling edge of the

serial clock input.

13

SCLK

Serial Clock Input. Data is clocked into the input shift register on the falling edge of the serial clock input. Data can be

transferred at rates of up to 35 MHz.

14

SYNC

Level Triggered Control Input (Active Low). This is the frame synchronization signal for the input data. When SYNC goes

low, it enables the input shift register, and data is then transferred in on the falling edges of the following clocks. The DAC

is updated on the rising edge of SYNC.

15

DGND

Ground Reference Pin for Digital Circuitry.

16

Negative Reference Voltage Input.

17, 18

Negative Analog Supply Connection. A voltage in the range of −16.5 V to −2.5 V can be connected to this pin.

19

AGND

Ground Reference Pin for Analog Circuitry.

20

Feedback Connection for External Amplifier. See the

AD5780 Features section for further details.

24

INV

Inverting Input Connection for External Amplifier. See the

AD5780 Features section for further details.

EPAD

must be decoupled to AGND. The paddle can be left electrically unconnected provided that a supply connection is made

performance.