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R61509V Target Spec
Rev. 0.11 April 25, 2008, page 137 of 181
Frame-Frequency Adjustment Function
The R61509V supports a function to adjust frame frequency. The frame frequency for driving liquid
crystal can be adjusted by setting the DIVI, RTNI bits without changing the oscillation frequency.
By changing the DIVI and RTNI settings, the R61509V can operate at high frame frequency when
displaying a moving picture, which requires the R61509V to rewrite data in high speed, and it can operate
at low frame frequency when displaying a still picture.
Relationship between Liquid Crystal Drive Duty and Frame Frequency
The following equation represent the relationship between liquid crystal drive duty and frame frequency.
The frame frequency can be changed by setting the 1H period adjustment bit (RTNI) and the operation
clock frequency division ratio setting bit (DIVI).
Equation for calculating frame frequency
][
)(/
Hz
BPFPLinetioDivisionRalineocksNumberofCl
fosc
encyFrameFrequ
++××
=
fosc: RC oscillation frequency
Number of clocks per line: RTNI bit
Division ratio: DIVI bit
Line: number of lines to drive the LCD panel (NL bit)
Number of lines for front porch: FP
Number of lines for back porch: BP
Example of Calculation: when maximum frame frequency = 60 Hz
fosc: 678 kHz
Number of lines: 432 lines
1H period: 25 clock cycles (RTNI [4:0] = “11001”)
Division ratio of operating clock: 1/1
Front porch: 2 lines
Back porch: 14 lines
f
FLM
= 678 (kHz) / 25 (clocks) × 1/1 × (432+2+14) (lines) ≒ 60.5 (Hz)