Manual/Software Adjustable Lcd Panel Negative Power Supply (Vlcd) - Epson S1D13706 Technical Manual

Epson Research and Development
Vancouver Design Center
Signal
GPO
CVOUT
X = don't care
Note

6.5 Manual/Software Adjustable LCD Panel Negative Power Supply (VLCD)

Signal
GPO
CVOUT
X = don't care
Note
S5U13706B00C Rev. 1.0 Evaluation Board User Manual
Issue Date: 01/02/23
The S5U13706B00C uses GPO and CVOUT to control the MAX754 as shown in the
following table..
Table 6-1: Controlling the MAX754
Turn MAX754 On
high
X
When JP5 is set to position 2-3, VDDH is adjustable using R24 (200Ω potentiometer) to
provide an output voltage from +24V to +40V.
When manually adjusting the voltage, set the potentiometer according to the panel's
specific power requirements before connecting the panel.
Most passive monochrome LCD panels require a negative bias voltage between -14V and
-24V. The S5U13706B00C uses a Maxim MAX749 Digitally Adjustable LCD Bias Supply
to provide this voltage range. The signal VLCD can be adjusted manually (using a potenti-
ometer) or controlled through software.
When JP7 is set to position 1-2, VLCD can be controlled through software to provide an
output voltage from -8V to -24V. CVOUT and GPO of the S1D13706 are connected to ADJ
and CTRL of MAX749. The output voltage (VLCD) can be adjusted from -8V to -24V in
64 steps by sending pulses to CVOUT. Each CVOUT pulse increments VLCD one step
towards -24V. When decremented beyond -24V, VLCD resets to -8V again. In other words,
63 pulses equal incrementing 1 step. After the MAX749 is reset (see "Controlling the
MAX749" on page 21), VLCD is set at -16V.
The S5U13706B00C uses GPO and CVOUT to control the MAX749 as shown in the
following table..
Table 6-2: Controlling the MAX749
Turn MAX749 On
high
X
When jumper JP7 is set to position 2-3, VLCD can be adjusted by R41 (500K potenti-
ometer) to provide an output voltage from -16V to -23V.
When using manual adjust, set the potentiometer according to the panel's specific power
requirements before connecting the panel.
Turn MAX754 Off
low
low
Turn MAX749 Off
low
low
Reset MAX754
low
high
Reset MAX749
low
high
S1D13706
X31B-G-004-04
Page 21