AD8565/AD8566/AD8567
Rev. G | Page 11 of 16
TOTAL HARMONIC DISTORTION + NOISE (THD + N)
The AD8565/AD8566/AD8567 feature low total harmonic dis-
tortion
. Figure 31 shows THD + N vs. frequency. The THD + N
over the entire supply range is below 0.008%. When the device
is powered from a 16 V supply, the THD + N stays below
configuration.
FREQUENCY (Hz)
20
T
HD+
N
(
%)
100
10
1
0.01
0.1
1k
10k
30k
VS = ±2.5V
VS = ±8V
01909-
031
Figure 31. THD + N vs. Frequency
SHORT-CIRCUIT OUTPUT CONDITIONS
The AD8565/AD8566/AD8567 do not have internal short-
circuit protection circuitry. As a precautionary measure, it is
recommended not to short the output directly to the positive
power supply or to ground.
It is not recommended to operate the AD8565/AD8566/AD8567
with more than 35 mA of continuous output current. The
output current can be limited by placing a series resistor at the
output of the amplifier whose value can be derived using
mA
35
S
X
V
R ≥
For a 5 V single-supply operation, RX should have a minimum
value of 143 .
LCD PANEL APPLICATIONS
The AD8565/AD8566/AD8567 amplifier is designed for LCD
panel applications or applications where large capacitive load
drive is required. It can instantaneously source/sink greater than
250 mA of current. At unity gain, it can drive 1 F without
compensation. This makes the AD8565/AD8566/AD8567 ideal
for LCD VCOM driver applications.
To evaluate the performance of the AD8565/AD8566/AD8567,
a test circuit was developed to simulate the VCOM driver
application for an LCD panel.
Figure 32 shows the test circuit.
Series capacitors and resistors connected to the output of the op
amp represent the load of the LCD panel. The 300 and 3 k
feedback resistors are used to improve settling time. This test
circuit simulates the worst-case scenario for a VCOM. It drives a
represented load that is connected to a signal switched symmet-
rically around VCOM.
Figure 33 shows a scope photo of the instantaneous output peak
current capability of the AD8565/AD8566/AD8567.
INPUT 0V TO 8V
SQUARE WAVE WITH
15.6s PULSE WIDTH
300
3k
10
10
10
10
10nF
MEASURE
CURRENT
4V
8V
10
TO 20
01909-
032
Figure 32. VCOM Test Circuit with Supply Voltage at 16 V
TIME (2s/DIV)
01909-
033
CH 2 = 100mA/DIV
CH 1 = 5V/DIV
10
0%
100
90
Figure 33. Scope Photo of the VCOM Instantaneous Peak Current