Rainbow Electronics MAX5133 - Manual (Page 18)

MAX5132/MAX5133
+5V/+3V, 13-Bit, Serial, Force/Sense DACs
with 10ppm/°C Internal Reference
18 ______________________________________________________________________________________
DAC
OUT
MAX5132
MAX5133
10k
26k
FB
REF V
DD
DGND AGND
+5V/
+3V
AC
REFERENCE
INPUT
500mVp-p
MAX495
+5V/+3V
Figure 13. External Reference with AC Components
Using an External Reference
with AC Components
The MAX5132/MAX5133 have multiplying capabilities
within the reference input voltage range specifications.
Figure 13 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 (V DD ) with a 4.7µF
capacitor in parallel with a 0.1µF capacitor to AGND.
Minimize lead lengths to reduce lead inductance.
Layout Considerations
Digital and AC signals coupling to 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 a low-inductance
ground plane. Wire-wrapped boards and sockets are
not recommended. If noise becomes an issue, shield-
ing may be required.
___________________Chip Information
TRANSISTOR COUNT: 3308
SUBSTRATE CONNECTED TO AGND.