PT6332 Datasheet, PDF (19/37 Pages) Princeton Technology Corp – VFD Driver/Controller IC

VFD Driver/Controller IC
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PT6332
MULTIPLE KEY PRESSES
The PT6332, even without diodes in the key scan lines, can scan for any combination of dual key
presses, any combination of triple key presses on any of the KI1 to KI5 key scan input pin lines, or any
combination of multiple key presses on any of the KS1 to KS5 key scan output lines. However, keys
that are not pressed may be seen as having been pressed for any other multiple key press combination.
Accordingly, applications must insert diodes at each key. Also, to reject any triple and higher multiple
key presses, if three or more data readout are 1 ignore the data by the software or in other ways.
NOTES ON THE /BLK PIN AND DISPLAY CONTROL
Since the states of the IC internal data (D1 to D168, and the control data) are undefined when power is
first applied, applications should turn off the display (i.e. set SG1 to SG56 and GR1 to GR3 low) by
setting the /BLK pin low at the same time as power is applied. Applications should transfer all 264 bits
of the serial data while /BLK is held low, and only then set /BLK high. This will prevent random
meaningless display at power on. (see figure 6)
ton
V DD
toff1
toff2
VFL
/BLK
CE
Internal data
D1 to D56
C ontrol data
Internal data
D5 7 to D 112
Internal data
D 113 to D1 68
Display and control data transfer
Undefined
V IL
tc
V IL
Defined
Undefined
Undefined
Defined
Undefined
Undefined
Defined
Figure 6
Undefined
ton > 0
toff1 > 0
toff2 > 0 ( toff1 > to ff2 )
tc ⋅⋅⋅⋅⋅⋅⋅⋅⋅⋅1 0µ s mi n.
PT6332 V1.0
- 19 -
February, 2006