AD8565/AD8566/AD8567
Figure 5 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 Ω and 3 kΩ 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 symmetrically around VCOM. Figure 6 displays
a scope photo of the instantaneous output peak current capability
of the AD856x family.
300⍀
8V
3k⍀
INPUT 0V TO 8V
SQUARE WAVE WITH
15.6s PULSEWIDTH
10⍀ 10⍀ 10⍀ 10⍀
4V
MEASURE
CURRENT
10nF
10nF
10nF
10nF
10⍀–20⍀
Figure 5. VCOM Test Circuit with Supply Voltage at 16 V
100
90
CH 2 =
100mA/DIV
CH 1 = 5V/DIV
10
0%
TIME – 2s/DIV
Figure 6. Scope Photo of the VCOM Instantaneous
Peak Current
–10–
REV. A