MAX5139 データシートの表示（PDF） - Maxim Integrated

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MAX5139

Low-Power, Single, 16-/12-Bit, Buffered Voltage-Output DACs

Maxim Integrated 

PIN

1, 4, 9

2

3

5

6

7

8

10

11

12

13

14

15

16

—

MAX5138/MAX5139

Low-Power, Single, 16-/12-Bit,

Buffered Voltage-Output DACs

NAME

N.C.

M/Z

LDAC

SCLK

CS

DIN

AGND

READY

DVDD

OUT

AVDD

REFI

REFO

AGND

EP

Pin Description

FUNCTION

No Connection. Not internally connected.

Power-Up Reset Select. Connect M/Z low to AGND to power up the DAC output. Connect M/Z

high to power up the DAC output to midscale.

Load DAC. Active-low hardware load DAC input.

Serial-Clock Input

Active-Low Chip-Select Input

Data In

Analog Ground. Internally connected to AGND. Connect AGND to AGND externally.

Data Output

Digital Power Supply. Bypass DVDD with a 0.1μF capacitor to AGND.

Buffered DAC Output

Analog Power Supply. Bypass AVDD with a 0.1μF capacitor to AGND.

Reference Voltage Input. Bypass REFI with a 0.1μF capacitor to AGND.

Reference Voltage Output

DAC Ground. Internally connected to AGND. Connect AGND to AGND externally.

Exposed Pad. Not internally connected. Connect EP to AGND or leave unconnected. Not

intended as an electrical connection point.

Detailed Description

The MAX5138/MAX5139 are a family of single-channel,

pin-compatible and software-compatible, 16-bit and 12-

bit DACs. The parts are low-power, buffered voltage-

output, high-linearity DACs. The MAX5138/MAX5139

minimize the digital noise feedthrough from input to out-

put by powering down the SCLK and DIN input buffers

after completion of each 24-bit serial input. On power-

up, the MAX5138/MAX5139 reset the DAC output to zero

or midscale, depending on the state of the M/Z input,

providing additional safety for applications that drive

valves or other transducers that need to be off on power-

up. The MAX5138/MAX5139 contain a segmented resis-

tor string-type DAC, a serial-in parallel-out shift register,

a DAC register, power-on reset (POR) circuit, and con-

trol logic. On the falling edge of the clock (SCLK) pulse,

the serial input (DIN) data is shifted into the device, MSB

first. During power-down, an internal 80kΩ resistor pulls

DAC outputs to AGND.

Output Amplifier (OUT)

The MAX5138/MAX5139 include an internal buffer for the

DAC output. The internal buffer provides improved load

regulation and transition glitch suppression for the DAC

output. The output buffer slews at 1.25V/µs and drives up

to 2kΩ in parallel with 200pF. The analog supply voltage

(AVDD) determines the maximum output voltage range

of the device as AVDD powers the output buffer.

DAC Reference

Internal Reference

The MAX5138/MAX5139 feature an internal reference

with a nominal +2.44V output. Connect REFO to REFI

when using the internal reference. Bypass REFO to

AGND with a 47pF (maximum 100pF) capacitor.

Alternatively, if heavier decoupling is required, add a

1kΩ resistor in series with a 1µF capacitor in parallel

with the existing 100pF capacitor. REFO can deliver up

to 100µA of current with no degradation in perfor-

mance. Configure other reference voltages by applying

a resistive potential divider with a total resistance

greater than 33kΩ from REFO to AGND.

External Reference

The external reference input features a typical input

impedance of 113kΩ and accepts an input voltage

from +2V to AVDD. Connect an external voltage

supply between REFI and AGND to apply an ex-

ternal reference. Leave REFO unconnected. Visit

www.maximintegrated.com/products/references for

a list of available external voltage-reference devices.

Maxim Integrated

9

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