MAX5120/MAX5121
+3V/+5V, 12-Bit, Serial Voltage-Output DACs
with Internal Reference
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Figure 14. External Reference with AC Components
Using an External Reference
with AC Components
The MAX5120/MAX5121 have multiplying capabilities
within the reference input voltage range specifications.
Figure 14 shows a technique for applying a sinusoidal
input to REF, where the AC signal is offset before being
applied to the reference input.
Power-Supply and Bypassing
Considerations
On power-up, the input and DAC registers are cleared
to either zero (RSTVAL = DGND) or midscale (RSTVAL
= V
DD
). Bypass the power supply with a 4.7µF capaci-
tor in parallel with a 0.1µF capacitor to AGND. Minimize
lead lengths to reduce lead inductance.
Layout Considerations
Digital and AC transient signals coupling to AGND can
create noise at the output. Connect AGND to the high-
est quality ground available. Use proper grounding
techniques, such as a multilayer board with a low-
inductance ground plane. Wire-wrapped boards and
sockets are not recommended. If noise becomes an
issue, shielding may be required.
