三合微科股�½有限公司
S
AM
H
OP
Microelectronics Corp.
SM5221-001/002
32 KEYS ENCODER
BLOCK DIAGRAM
OSCI
OSCO
V
DD
Vss
OSC CIRCUIT
KI
0
OUTPUT
KI
1
KEY INPUT SCAN
CIRCUIT
TIMING GENERATION & CONTROL
CIRCUIT
CONTROL
CIRCUIT
DOUT
LED
CODE GENERATION CIRCUIT
KI
2
CODE
KI
3
KEY INPUT/OUTPUT SCAN CIRCUIT
SEL
KI/O0 KI/O1 KI/O2 KI/O3 KI/O4 KI/O5 KI/O6 KI/O7
FUNCTION DESCRIPTION
(1) Oscillation
The SM5221-001/002 oscillation circuit is designed for use of a 400 kHz or 500 kHz ceramic
resonator, but there may be mutual influence between variations in the IC and ceramic
resonator resulting in abnormal oscillation. The oscillation circuit starts to operate when a key
is depressed.
C
1
C
2
OSCI
OSCO
Page 3
V.2.0 Mar 8,2002
SAMHOP [ SAMHOP MICROELECTRONICS CORP. ]
