BU91501KV-M Datasheet, PDF (12/34 Pages) Rohm – Multi- function LCD Segment Drivers

BU91501KV-M
Datasheet
Sleep Mode
KS1/S42 - KS6/S47 pins are set high or low by SLP CTRL P3,P2 data. (Refer to the SLP CTRL description).
If a key on one of the lines corresponding to a KS1 to KS6 pin which is set high is pressed, the oscillator on the OSC pin
is started and a key scan is performed. Keys are scanned until all keys are released. Multiple key presses are recognized
by determining whether multiple key data bits are set.
If a key is pressed for longer than 610T(s)(Where T=1/fosc (When External clock input, fosc is a quarter of external
clock)) the BU91501KV-M outputs a key data read request (a low level on DO) to the controller. The controller
acknowledges this request and reads the key data. However, if CSB is ”L” during a serial data transfer, DO will be set
high.
After the controller reads the key data, the key data read request is cleared (DO is set high) and the BU91501KV-M
performs another key scan. However, this does not clear sleep mode. Also note that DO can be controlled to be an
open-drain output or a CMOS output. During open-drain output selection, DO is an open-drain output so a pull-up
resistor (between 1 KΩ and 10KΩ) is required.
Sleep mode key scan example
Example: when SLP CTRL P3= [0], P2= [1] (sleep with only KS6 high)
(Note8) These diodes are required to reliably recognize multiple key presses on the KS6 line when sleep mode state with only KS6 high, as in the
above example. That is, these diodes prevent incorrect operations due to sneak currents in the KS6 key scan output signal when keys on the KS1 to
KS5 lines are pressed at the same time.
Key Input 1
Key Scan
610T[s]
CSB
Serial data transfer
Serial data transfer
SD
610T[s]
Key RD
Command (85H)
Serial data transfer
Key RD
Command (85H)
DO
Key data read
Key data read
Key data read request
Key data read request
 ^T

1
fosc

External Clock Input
：
 ^T

1
fosc
/
4

Figure 12. Key scan operation in sleep mode
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