Output Clamp Feature - Analog Devices AD8556-EVALZ User Manual

AD8556-EVALZ/AD8556CP-EBZ User Guide
In Figure 6, overall gain = 100 (G1 = default = 4, G2 = Code 1 =
25, offset = 2.5 V or Code 128).
[
T
T
1
2
B W
Ch1 50.0mV Ch2 2.00V
Figure 6. Output with Overall Gain = 100
In Figure 7, V = 2 mV p-p, G1 = 6.4, G2 = 35, and offset =
IN
2.5 V or Code 128.
[
T
T
1
2
Ch1 20.0mV B W Ch2 2.00V
Figure 7. Output at V = 2 mV p-p, G1 = 6.4, G2 = 35, Offset = 2.5 V
IN

OUTPUT CLAMP FEATURE

The output of the device can be clamped to the desired level.
The output clamp feature is provided to protect the circuitry
that follows the AD8556-EVALZ, in case the input to
EVALZ is accidentally larger than anticipated.
In normal situations (V
SUPPLIES
input = 40 mV p-p), the response to an input is as shown in
Figure 8.
]
B W
M 400ms A Ch1 2.00mV
T 9.600%
]
B W M 400ms A Ch1 –1.20mV
T 9.600%
AD8556-
= ±2.5 V, gain = 70, V = 2.5 V,
OFFSET
1
2
Ch1 20.0mV
Figure 9 shows the output after VCLAMP is set to 0.8 V.
1
2
Ch1 20.0mV
Applying a large gain to an input yields saturation, as shown in
Figure 10. The conditions are V
200, offset = 2.5 V.
T
1
2
Ch1 20.0mV
Note that Resistor RT1 and Resistor RT2 are used for pulse
stretching; do not adjust them. They are factory-adjusted for
optimal results.
Rev. A | Page 7 of 9
[ ]
T
T
B W Ch2 2.00V B W M 100ms A Ch1
T 0.00000s
Figure 8. Normal Response
[ ]
T
T
B W B W
Ch2 2.00V M 100ms A Ch1
T 0.00000s
Figure 9. Response with VCLAMP Set
= 20 mV p-p, G1 = 6.4, G2 =
IN
[ ]
T
B W B W
Ch2 2.00V M 400ms A Ch1
T 9.600%
Figure 10. Results with Saturation
UG-896
2.00mV
2.00mV
–1.20mV