ST7669 datasheet(59/216 Pages) SITRONIX

59 / 216 page

ST7669

Ver 1.3a

59/216

3/2/2009

7.9.2

Voltage Follower Circuits

There is a build-in voltage follower circuits in ST7669 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

(2/N) x V0

(1/N) x V0

N=5 to 14

7.9.3

OTP Setting Flow

ST7669 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 7.9-2

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 to OTP, the voltage of VPP must be 7.50~7.75V; 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.

ST7669 Datasheet(PDF) 59 Page - Sitronix Technology Co., Ltd.