HX8347 - Adafruit

HX8347-G(T)240RGB x 320 dot, 262K color, TFT Mobile Single Chip Driver5.14.2 Brightness control blockDATA SHEET Preliminary V01There is an external output signal from brightness block, CABC_PWM_OUT, tocontrol the LED driver IC in order to control display brightness.There are resister bits, DBV[7:0] of R3Ch, for display brightness of manual brightnesssetting. The CABC_PWM_OUT duty is calculated as DBV[7:0]/255 x CABC duty(generated after one-frame display data content analysis).For example: CABC_PWM_OUT period = 2.95 ms, and DBV[7:0](R3Ch) = ‘228 DEC ’and CABC duty is 74%. Then CABC_PWM_OUT duty = 228 / 255 x 74% ≡ 65.90%.Correspond to the CABC_PWM_OUT period = 2.95 ms, the high-level ofCABC_PWM_OUT (high effective) = 1.94ms, and the low-level of CABC_PWM_OUT= 1.01ms.One PeriodCABC_PWM_OUTONOFFDisplayBrightnessDuty = 100%OFFDuty = 100%MaximumDuty = 33% Duty = 65.90%Figure 5.43: CABC_PWM_OUT output dutyWhen Architecture II module is used (BL=’0’) with the example below, theCABC_PWM_OUT is always output low and the DBV[7:0](R3Ch) will be read a valueas 169 DEC (169/255≡ 66.27%).Himax ConfidentialFor Go-tek OnlyThis information contained herein is the exclusive property of Himax and shall not be distributed, reproduced, or disclosedin whole or in part without prior written permission of Himax.-P.115-October, 2009