Rainbow Electronics DS4432 - Manual (Page 9)

DS4432
Dual-Channel, I
2
C, 7-Bit Sink/Source
Current DAC
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I OUT0 is chosen to be 100µA (midrange source/sink
current for the DS4432). Summing the currents into the
feedback node, we have the following:
where
and
To create a 20% margin in the supply voltage, the value
of V
OUT is set to 2.4V. With these values in place, R 0B
is calculated to be 2.67k
Ω, and R
0A is calculated to be
4k
Ω. The current DAC in this configuration allows the
output voltage to be moved linearly from 1.6V to 2.4V
using 127 settings. This corresponds to a resolution of
6.3mV/step.
V CC Decoupling
To achieve the best results when using the DS4432,
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
V V
R
R A
OUT FB
A
0
0
=
−
I
V
R
R B
FB
B
0
0
=
I I I
OUT R B R A 0 0 0
= −
DC-DC
CONVERTER
FB
OUT
SDA
SCL
OUT0
GND
R FS0 = 80k Ω
4.7k Ω 4.7k Ω V CC
V
CC
V
OUT
= 2.0V*
FS0
R 0B = 2.67k Ω
R
0A
= 4k Ω
V FB = 0.8V*
I R0A
I R0B
I OUT0
DS4432
*V OUT AND V FB VALUES ARE DETERMINED BY THE DC-DC CONVERTER AND SHOULD NOT BE CONFUSED WITH V OUT AND V RFS OF THE DS4432.
Figure 3. Example Application Circuit
PACKAGE TYPE PACKAGE CODE DOCUMENT NO.
8 µSOP U8+1 21-0036
Package Information
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