10-Bit, 40MHz, Current/Voltage-Output DACs

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9

Ω) sets

External Reference

To disable the MAX5181/MAX5184’s internal reference,

connect

reference may now be applied to drive the REFO pin to

set the full-scale output (Figure 3). Choose a reference

capable of supplying at least 150µA to drive the bias

circuit that generates the cascode current for the cur-

rent array. For improved accuracy and drift perfor-

mance, choose a fixed output voltage reference such

as the 1.2V, 25ppm/°C MAX6520 bandgap reference.

Standby Mode

To enter the lower-power standby mode, connect digital

inputs PD and DACEN to DGND. In standby, both the

reference and the control amplifier are active with the

current array inactive. To exit this condition, DACEN

must be pulled high with PD held at DGND. The

MAX5181/MAX5184 typically require 50µs to wake up

and let both outputs and the reference settle.

Shutdown Mode

For lowest power consumption, the MAX5181/MAX5184

provide a power-down mode in which the reference, con-

trol amplifier, and current array are inactive and the DAC

supply current is reduced to 1µA. To enter this mode,

required for the parts to leave shutdown mode and settle

to their outputs’ values prior to shutdown. Table 1 lists the

power-down mode selection.

Timing Information

Figure 4 shows a detailed timing diagram for the

MAX5181/MAX5184. With each high transition of the

clock, the input latch is loaded with the digital value set

by bits D9 through D0. The content of the input latch is

then shifted to the DAC register, and the output up-

dates at the rising edge of the next clock.

Outputs

The MAX5181 output is designed to supply full-scale

output currents of 1mA into 400

Ω loads in parallel with

a capacitive load of 5pF. The MAX5184 features inte-

grated 400

Ω resistors that restore the array current to

proportional, differential voltages of 400mV. These dif-

ferential output voltages can then be used to drive a

balun transformer or a low-distortion, high-speed oper-

ational amplifier to convert the differential voltage into a

single-ended voltage.

9.6k

Ω

REFR

AGND

AGND

DGND

REFO

MAX4040

1.2V

BANDGAP

REFERENCE

REN

CURRENT-

SOURCE ARRAY

**9.6k

ΩREFERENCE CURRENT-SET RESISTOR

INTERNAL TO MAX5184 ONLY. USE EXTERNAL

OPTIONAL EXTERNAL BUFFER

FOR HEAVIER LOADS

MAX5181

MAX5184