Detailed Description

The MAX5232/MAX5233 10-bit, voltage-output DACs

are easily configured with a 3-wire SPI-, QSPI-,

MICROWIRE-compatible serial interface. The devices

include a 16-bit data-in/data-out shift register and have

an input consisting of an input register and a DAC reg-

ister. In addition, these devices employ precision

trimmed internal resistors to produce a gain of

1.6384V/V, maximizing the output voltage swing, and a

programmable-shutdown output impedance of 1k

Ω or

200k

Ω The full-scale output voltage is 4.092V for the

MAX5233 and 2.046V for the MAX5232. These devices

produce a weighted output voltage proportional to the

network (Figure 3).

Internal Reference

The MAX5230/MAX5231 use an on-board precision

bandgap reference to generate an output voltage of

1.234V (MAX5232) or 2.465V (MAX5233). With a low

temperature coefficient of only 10ppm/°C, REF can

source up to 100µA and is stable for capacitive loads

less than 200pF.

Output Amplifiers

The output amplifiers have internal resistors that pro-

vide for a gain of 1.6384V/V when OS_ is connected to

AGND. The output amplifiers have a typical slew rate of

0.6V/µs and settle to 1/2LSB within 10µs with a load of

5k

Ω in parallel with 100pF. Use the serial interface to

set the shutdown output impedance of the amplifiers to

1k

Ω or 200kΩ.

OS_ can be used to produce an offset voltage at the

output. For instance, to achieve a 1V offset, apply -1V

to OS_ to produce an output range from 1V to (1V +

ited by the maximum output voltage specification.

3V/5V, 10-Bit, Serial Voltage-Output Dual DACs

with Internal Reference

______________________________________________________________________________________

11

CS

SCLK

DIN

DOUT

LDAC

Figure 2. Detailed Serial Interface Timing

OUT_

OS_

SHOWN FOR ALL ONES ON DAC

D9

D8

D7

D0

2R

121k

Ω

77.25k

Ω

1k

Ω

2R

2R

2R

2R

RR

R

REF

AGND

Figure 3. Simplified DAC Circuit Diagram

Rail-to-Rail is a registered trademark of Nippon Motorola, Ltd.