STFPC311 Datasheet, PDF (31/39 Pages) STMicroelectronics – Front panel controller/driver with standby power management

STFPC311
12 Timing characteristics
12 Timing characteristics
Note:
Table 10.
Symbol
Timing characteristics ( V_DD= 3.3V, T_A= -20 to 70°C, unless otherwise noted.
Typical values are at T_A= 25°C )
Parameter
Test conditions
Values
Unit
Min. Typ. Max.
PW_CLK Clock Pulse Width
400
ns
PW_STB Strobe Pulse Width
1
µs
t_SETUP Data Setup Time
100
ns
t_HOLD Data Hold Time
100
ns
t_CLK-STB Clock-Strobe Time
CLK
STB
1
µs
t_{WAIT Wait Time} ⁽¹⁾
CLK
CLK
1
µs
1. Refer to page on Serial Communication Format.
The pulse width of the segment signal is derived from the oscillator frequency. The value can be
modified by trimming ROSC. One cycle of key scanning consists of one frame and data of 12 x
2 matrices are stored in RAM.
The key scan is only at the end of the frame when the display is ON. When the display is OFF,
the key scan takes place continuously. The grid is turned off during the key scan.
Figure 27. Key scanning and display timing
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