Rainbow Electronics MAX5157 - Manual (Page 14)

MAX5156/MAX5157
Using an AC Reference
In applications where the reference has an AC signal
component, the MAX5156/MAX5157 have multiplying
capabilities within the reference input voltage range
specifications. Figure 12 shows a technique for apply-
ing a sinusoidal input REF_, where the AC signal is off-
set before being applied to the reference input.
Harmonic Distortion and Noise
The total harmonic distortion plus noise (THD+N) is typ-
ically less than -80dB at full scale with a 1Vp-p input
swing at 5kHz. The typical -3dB frequency is 600kHz
for both devices, as shown in the
Typical Operating
Characteristics .
Low-Power, Dual, 12-Bit Voltage-Output DACs
with Configurable Outputs
14 ______________________________________________________________________________________
MAX5156
MAX5157
DAC
V
OUT
=
(
1 + R1
) (
N
)(
V REF_
)
R2 4096
REF_
V OUT
FB_
OUT_
AGND DGND
+5V/+3V
V DD
R1
R2
Figure 10. Configurable Output Gain
AGND DGND
MAX5156
MAX5157
DAC _
REF_
OUT_
FB_
10k 10k
V-
V+
V DD
V
OUT
+5V/+3V
Figure 11. Bipolar Output Circuit
DAC_
OUT_
FB_
MAX5156
MAX5157
10k
26k
REF_ V DD
DGND AGND
+5V/
+3V
AC
REFERENCE
INPUT
500mVp-p
MAX495
+5V/+3V
Figure 12. AC Reference Input Circuit
Table 3. Bipolar Code Table
0 0 0 0 0 0 0 0 0 0 0 1 ( 0 )
0 0 0 0 0 0 0 0 0 0 0 0 ( 0 )
0 1 1 1 1 1 1 1 1 1 1 1 ( 0 )
0V 1 0 0 0 0 0 0 0 0 0 0 0 ( 0 )
DAC CONTENTS
MSB LSB
1 0 0 0 0 0 0 0 0 0 0 1 ( 0 )
1 1 1 1 1 1 1 1 1 1 1 1 ( 0 )
ANALOG OUTPUT
+V
2047
2048 REF

 

+V
1
2048
REF

 

-V
1
2048 REF

 

-V
2047
2048
REF

 

-V
2048
2098
- V
REF REF

 

=
Note: ( ) are for the sub bit.