MSC1201-XX OKI electronic componets, MSC1201-XX Datasheet - Page 13

• Manufacturer Part Number: MSC1201-XX
• Description: 60-Bit VFD Tube Driver
• Manufacturer: OKI electronic componets

¡ Semiconductor
PWM Conversion
In the PWM conversion mode, "lamp PWM", which is used for dimming control of back-light for
instrument clusters or other displays, is used to generate the PWM signal for VFD tube dimming
control. The lamp PWM input to "PWM IN" pin is converted to PWM signal for VFD tube with
a built-in PWM conversion look-up table (User-Programmable Mask ROM).
The duty
Note: The duty cycle of the lamp PWM signal is measured with a reference point of 2.5 V typ.
GRID/SEG Driver Operation and Digital/Analog Dimming Operation
Figure 6 shows an output timing of the GRID and SEG Driver when the VK is "H" level.
Output timings of the GRID and SEG drivers are shown in figure 7 for the digital dimming mode
operation in figure 8 for the PWM conversion mode operation.
(1) GRID and SEG drivers output timings when VK = "H"
Note: One bit time = 2/f
GRID1
GRID2
SEG1-30
PWMIN
As the reference point of 2.5 V is the threshold voltage of "PWM IN" pin, it deviates to
some value between 0.8 V and 3.8 V due to process parameter deviation. Therefore, the
PWM conversion error increases as the rise/fall time of the lamp PWM increases.
cycle of the lamp PWM is defined as follows:
Fig. 6 GRID and SEG Output Timing (VK = "H")
OSC
PWM Input Frequency = 256 ± 80Hz
Duty Cycle = A / (A+B)
= 1 ms typ.
A
6-bit times
2038-bit times
2032-bit times
1 Frame (4096-bit times)
f
FR
B
10-bit times
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16-bit times
5V
MSC1201-xx
13/20