SP9600DS/04

SP9600 12-Bit, Low Power Voltage Output D/A Converter

© Copyright 2000 Sipex Corporation

4

THEORY OF OPERATION

The SP9600 consists of four main functional

blocks – the input shift register, DAC register,

12-Bit D/A converter and a output buffer

amplifier, Figure 1.

The input shift register is used to convert the

serial input data stream to a parallel 12–Bit

digital word. The input data is shifted on posi-

tive clock (SCLK) edges when the Chip Select

(CS) signal is in the “low” state. The MSB is

loaded first and LSB last. No shifting of the

input data occurs when the Chip Select (CS)

signal is in the “high” state.

The DAC register is used to store the digital

word which is sent to the R–2R DAC. Its value

is updated on the positive transition of the Chip

Select (CS) signal.

The 12–Bit D/A converter is an “inverted” R-2R

ladder network. The DAC itself is implemented

with precision thin-film resistors and CMOS

transmission gate switches. The resistor net-

work is laser-trimmed to achieve better than 12–

Bit accuracy. The D/A converter is used to

convert the 12-bit input word to a precision

voltage.

The operational amplifier is a rail-to-rail input,

rail-to-rail output CMOS amplifier. It is capable

of supplying 1mA of load current in the 1.5 to

3.5 output voltage range. The initial offset volt-

age is laser-trimmed to improve accuracy. Set-

tling time is 20

µs for a full scale output transi-

tion to 0.012% accuracy.

INPUT

OUTPUT

MSB

LSB

1111

1111

1111

V

REF

- 1 LSB

1111

1111

1110

V

REF

- 2 LSB

0000

0000

0001

AGND + 1 LSB

0000

0000

0000

AGND

(V

1 LSB =

Table 1. Binary Coding

FEATURES...

The SP9600 is a low power 12–Bit Digital-to-

Analog Converter. The converter features 0.5 to

4.5 volt output swings with a single +5V supply.

The input coding format used is standard binary,

Table 1.

This Digital-to Analog Converter uses a stan-

time is specified at 20

µs to full 12-bit accuracy

when driving a 10k

Ω, 10pF load combination.

The SP9600 Digital-to-Analog Converter is

ideally suited for applications such as ATE,

process controllers, robotics and instrumenta-

tion. The SP9600 is available in an 8-pin 0.15"

SOIC and 0.3" PDIP packages, specified over

commercial and industrial temperature ranges.

PIN ASSIGNMENTS

Pin 1- V

OUT

- Voltage Output.

Pin 2- V

Pin 3- SCLK - Serial Clock Input.

Pin 4- D

Pin 5- CS - Chip Select Input.

Pin 6 - DGND - Digital Ground

Pin 7- AGND - Analog Ground.

Pin 8- V

1

2

3

4

8

7

6

5

DGND

CS

AGND

SCLK

SP9600

PINOUT – 8-PIN PLASTIC DIP & SOIC