Digital Programmable Current Source

Figure 15 depicts a digitally programmable, unidirec-

tional current source that can be used in industrial con-

trol applications. The output current is:

where NB is the DAC code and R is the sense resistor.

Power-Supply Considerations

On power-up, the input and DAC registers clear (reset

a 4.7µF capacitor in parallel with a 0.1µF capacitor to

GND. Minimize lead lengths to reduce lead inductance.

Grounding and Layout Considerations

Digital and AC transient signals on AGND can create

noise at the output. Connect AGND to the highest quali-

ty ground available. Use proper grounding techniques,

such as a multilayer board with an unbroken, low-

inductance ground plane. Carefully lay out the traces

between channels to reduce AC cross-coupling and

crosstalk. Wire-wrapped boards and sockets are not

recommended. If noise becomes an issue, shielding

may be required.

Low-Power, Dual, 13-Bit Voltage-Output DACs

with Configurable Outputs

16

______________________________________________________________________________________

MAX5152

MAX5153

DAC_

REF_

2N3904

R

AGND

FB_

OUT_

+5V/+3V

DGND

Figure 15. Digitally Programmable Current Source