MAX530AEWG View Datasheet(PDF) - Maxim Integrated

Part Name

Description

Manufacturer

MAX530AEWG

+5V, Low-Power, Parallel-Input, Voltage-Output, 12-Bit DAC

Maxim Integrated 

+5V, Low-Power, Parallel-Input,

Voltage-Output, 12-Bit DAC

REFOUT

REFIN

ROFS

33µF

2.048V

REFERENCE

2N7002

REFGND

AGND

DGND

POWER-ON

RESET

CLR

A0

A1

CONTROL

LOGIC

CS

WR

LDAC

MAX530

DAC

12-BIT DAC LATCH

NBL

INPUT

LATCH

NBM

INPUT

LATCH

NBH

INPUT

LATCH

RFB

VOUT

VDD +5V

VSS

D0/D8 D2/D10

D4 D6

D1/D9 D3/D11 D5 D7

Figure 3. Low-Current Shutdown Mode

An additional 110µA of supply current can be saved

when the internal reference is not used by connecting

REFGND to VDD. A low on resistance N-channel FET,

such as the 2N7002, can be used to turn off the internal

reference to create a shutdown mode with minimum

current drain (Figure 3). When CLR is high, the transis-

tor pulls REFGND to AGND and the reference and DAC

operate normally. When CLR goes low, REFGND is

pulled up to VDD and the reference is shut down. At the

same time, CLR resets the DAC register to all 0s, and

the op-amp output goes to 0V for unity-gain and G = 2

Table 2. Input Latch Addressing

CLR CS WR LDAC A0 A1 DATA UPDATED

LXX

X

X X Reset DAC Latches

HHX

H

X X No Operation

HXH

H

X X No Operation

HLL

H

H H NBH (D8-D11)

HLL

H

H L NBM (D4-D7)

HLL

H

L H NBL (D0-D3)

HHH

L

X X Update DAC Only

HLL

X

L L DAC NOT UPDATED

HLL

L

H H NBH and Update DAC

modes. This reduces the total single-supply operating

current from 250µA (400µA max) to typically 40µA in

shutdown mode.

A small error voltage is added to the reference output

by the reference current flowing through the N-channel

pull-down transistor. The switch’s on resistance should

be less than 5Ω. A typical reference current of 100µA

would add 0.5mV to REFOUT. Since the reference cur-

rent and on resistance increase with temperature, the

overall temperature coefficient will degrade slightly.

As data is loaded into the DAC and the output moves

above GND, the op-amp quiescent current increases to

its nominal value and the total operating current aver-

ages 250µA. Using dual supplies (±5V), the op amp is

fully biased continuously, and the VDD supply current is

more constant at 250µA. The VSS current is typically

150µA.

The MAX530 logic inputs are compatible with TTL and

CMOS logic levels. However, to achieve the lowest

power dissipation, drive the digital inputs with rail-to-rail

CMOS logic. With TTL logic levels, the power require-

ment increases by a factor of approximately 2.

10 ______________________________________________________________________________________

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