Sink/Source Current DAC

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9

Applications Information

Example Calculation

for an Adjustable Power Supply

In this example, the Typical Operating Circuit is used

as a base to create Figure 3, a 2.0V voltage supply with

±20% margin. The adjustable power supply has a

the equation:

rent for the DS4412). Summing the currents into the

feedback node, we have the following

Where:

And

To create a 20% margin in the supply voltage, the value

calculated to be 267

The current DAC in this configuration allows the output

voltage to be moved linearly from 1.6V to 2.4V using 15

settings. This corresponds to a resolution of 25.8mV/step.

To achieve the best results when using the DS4412,

decouple the power supply with a 0.01µF or 0.1µF

capacitor. Use a high-quality ceramic surface-mount

capacitor if possible. Surface-mount components mini-

mize lead inductance, which improves performance,

and ceramic capacitors tend to have adequate high-

frequency response for decoupling applications.

I

VV

R

RA

OUT

FB

A

0

0

=

−

I

V

R

RB

FB

B

0

0

=

II

I

OUT

R B

R A

00

0

=

−

V

R

RR

V

FB

B

AB

OUT

=

+

×

0

00

DC-DC

CONVERTER

FB

OUT

SDA

SCL

OUT0

GND

Ω

4.7k

Ω

4.7k

Ω

FS0

Ω

Ω

DS4412

Figure 3. Example Application Circuit

PACKAGE TYPE

PACKAGE CODE

DOCUMENT NO.

8 µSOP

U8+1

21-0036

Package Information