MAX5811(2002) データシートの表示（PDF） - Maxim Integrated

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MAX5811
(Rev.:2002)

10-Bit, Low-Power, 2-Wire Interface, Serial, Voltage-Output DAC

Maxim Integrated 

10-Bit Low Power 2-Wire Interface Serial,

Voltage-Output DAC

MSB

LSB

MSB

S

A6

A5

A4

A3

A2

A1

A0

R/W

=0

ACK

C3 C2 X

X

X

LSB

X X X ACK

DATA BYTES GENERATED BY MASTER DEVICE

MSB

LSB

MSB

LSB

Sr

A6

A5

A4

A3

A2

A1

A0

R/W

=1

ACK

X X PD1 PD0 D9 D8 D7 D6 ACK

DATA BYTES GENERATED BY MAX5811

MSB

LSB

D5 D4 D3 D2 D1 D0 X X ACK

P

Figure 7. Read Word Data Sequence

ACK GENERATED BY

MASTER DEVICE

IN

OUT

MAX6030/

MAX6050

GND

VDD

MAX5811 OUT

GND

Figure 8. Powering the MAX5811 from an External Reference

data flow reverses following the address acknowledge

by the MAX5811. The device transmits the first byte of

data, waits for the master to acknowledge, then trans-

mits the second byte. Figure 7 shows an example read

data sequence.

I2C Compatibility

The MAX5811 is compatible with existing I2C systems.

SCL and SDA are high-impedance inputs; SDA has an

open drain that pulls the data line low during the ninth

clock pulse. The Typical Operating Circuit shows a typ-

ical I2C application. The communication protocol sup-

ports the standard I2C 8-bit communications. The

general call address is ignored. The MAX5811 address

is compatible with the 7-bit I2C addressing protocol

only. No 10-bit address formats are supported.

Digital Feedthrough Suppression

When the MAX5811 detects an address mismatch, the

serial interface disconnects the SCL signal from the

core circuitry. This minimizes digital feedthrough

caused by the SCL signal on a static output. The serial

interface reconnects the SCL signal once a valid

START condition is detected.

Applications Information

Powering the Device from an

External Reference

The MAX5811 uses the VDD as the DAC voltage refer-

ence. Any power-supply noise is directly coupled to the

device output. The circuit in Figure 8 uses a precision

voltage reference to power the MAX5811, isolating the

device from any power-supply noise. Powering the

MAX5811 in such a manner greatly improves overall

performance, especially in noisy systems. The

MAX6030 (3V, 75ppm/°C) or the MAX6050 (5V,

75ppm/°C) precision voltage references are ideal

choices due to the low power requirements of the

MAX5811.

Digital Inputs and Interface Logic

The MAX5811 2-wire digital interface is I2C and SMBus

compatible. The two digital inputs (SCL and SDA) load

the digital input serially into the DAC. Schmitt-trigger

buffered inputs allow slow-transition interfaces such as

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