ST7669V
7.8.2 VOLTAGE FOLLOWER CIRCUITS
There is a build-in voltage follower circuits in ST7669V for generating Vg and Vm. These voltages are decided by
bias ratio selection circuitry which is set by users with software to control 1/5 to 1/14 bias ratios to match the optimum
display performance of LCD panel. Bias driving rule is listed below:
LCD bias
1/N bias
Vg
Vm
(2/N) x V0
N=5 to 14
(1/N) x V0
7.8.3 OTP SETTING FLOW
ST7669V provides the Write and Read function to write the electronic control value and built-in resistance ratio into
OTP (One-time programming register), and then read them from it. Using the Write and Read functions, you can store
these values appropriate to each LCD panel. This function is very convenient for user in setting from some different panel’s
voltage. But using this function must attention the setting procedure. Please see the following diagram.
Figure 7.3-6 OTP programming flow
Note1: This setting flow is used for LCM assembler.
Note2: OTP shouldn’t be written without preceding loading correctly from OTP in order to avoid some
errors during IC operation.
Note3: When writing value to OTP, the voltage of VPP must be 7.5V~7.75V; the current of Ivpp must be
more than 4 mA.
Note4: If the OTP is exposed to a high temperature for hours, data in the memory cell may probably be
lost before the data retention guarantee period. To retain data in the memory cell, keep the memory cell
below 90
℃
. The data retention guarantee period is specified including the retention period.
Ver 1.3
54/208
6/4/2008
SITRONIX [ SITRONIX TECHNOLOGY CO., LTD. ]
