MAX5362(2001) Просмотр технического описания (PDF) - Maxim Integrated

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MAX5362
(Rev.:2001)

Low-Cost, Low-Power 6-Bit DACs with 2-Wire Serial Interface in SOT23 Package

Maxim Integrated 

Low-Cost, Low-Power 6-Bit DACs with

2-Wire Serial Interface in SOT23 Package

VDD

REF

SDA

CONTROL

SCL

LOGIC

CURRENT-

STEERING

DAC

255

DATA LATCH

6+2

SERIAL INPUT

REGISTER

MAX5360

MAX5361

MAX5362

OUT

10k

GND

VREF

SW1

SW2

SW255

OUT

Figure 1. Functional Diagram

Table 1. Unipolar Code Current

DAC CODE

6 BITS + 2 SUBBITS

111111 (00)

100000 (00)

000001 (00)

000000 (00)

MAX5360

2V ✕ (63/64)

1V

31mV

0

Figure 2. Current-Steering Topology

OUTPUT VOLTAGE

MAX5361

4V ✕ (63/64)

2V

62mV

0

MAX5362

0.9 ✕ VDD ✕ (63/64)

0.9 ✕ VDD / 2

0.9 ✕ VDD / 64

0

Detailed Description

The MAX5360/MAX5361/MAX5362 voltage-output, 6-bit

DACs offer full 6-bit performance with less than 1LSB

integral nonlinearity (INL) error and less than 1LSB dif-

ferential nonlinearity (DNL) error ensuring monotonic

performance. The devices use a simple two-wire, fast-

mode I2C-compatible serial interface that operates up

to 400kHz. The MAX5360/MAX5361/MAX5362 include

an internal reference, an output buffer, and low-current

shutdown mode, making them ideal for low-power,

highly integrated applications. Figure 1 shows the

devices’ functional diagram.

Analog Section

The MAX5360/MAX5361/MAX5362 employ a current-

steering DAC topology as shown in Figure 2. At the

core of the DAC is a reference voltage-to-current con-

verter (V/I) that generates a reference current. This cur-

rent is mirrored to 255 equally weighted current

sources. DAC switches control the outputs of these cur-

rent mirrors, so only the desired fraction of the total cur-

rent-mirror currents is steered to the DAC output. The

current is then converted to a voltage across a resistor,

and this voltage is buffered by the output buffer amplifier.

Output Voltage

Table 1 shows the relationship between the DAC code

and the analog output voltage. The 6-bit DAC code is

binary unipolar with 1LSB = (VREF / 64). The MAX5360/

MAX5361 have a full-scale output voltage of (+2V -

1LSB) and (+4V - 1LSB), respectively, set by the inter-

nal references. The MAX5362 has a full-scale output

voltage of (0.9 ✕ VDD - 1LSB). Each device accepts 8-bit

DAC codes, but the accuracy is guaranteed only for

6 bits.

Output Buffer

The DAC voltage output is an internally buffered unity-

gain follower that typically slews at ±0.4V/µs. The out-

put can swing from 0 to full scale. With a 1/4 FS to 3/4

FS output transition, the amplifier outputs typically settle

to 1/2LSB in less than 5µs when loaded with 10kΩ in

parallel with 50pF. The buffer amplifiers are stable with

any combination of resistive loads >10kΩ and capaci-

tive loads <50pF.

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