X51638
PIN DESCRIPTION
PIN
PIN
(SOIC/PDIP)
TSSOP
Name
Function
Chip Select Input. CS HIGH, deselects the device and the SO output pin
is at a high impedance state. Unless a nonvolatile write cycle is underway,
the device will be in the standby power mode. CS LOW enables the device,
placing it in the active power mode. Prior to the start of any operation after
power up, a HIGH to LOW transition on CS is required
1
1
CS/WDI
Watchdog Input. A HIGH to LOW transition on the WDI pin restarts the
Watchdog timer. The absence of a HIGH to LOW transition within the
watchdog time-out period results in RESET going active.
Serial Output. SO is a push/pull serial data output pin.A read cycle shifts data
out on this pin.The falling edge of the serial clock (SCK) clocks the data out.
2
5
2
8
SO
SI
Serial Input. SI is a serial data input pin. Input all opcodes, byte addresses,
and memory data on this pin.The rising edge of the serial clock (SCK) latches
the input data. Send all opcodes (Table 1), addresses and data MSB first.
Serial Clock. The Serial Clock controls the serial bus timing for data input and
output.The rising edge of SCK latches in the opcode, address, or data bits
present on the SI pin.The falling edge of SCK changes the data output on the
SO pin.
6
3
9
6
SCK
WP
Write Protect. The WP pin works in conjunction with a nonvolatile WPEN
bit to “lock” the setting of the Watchdog Timer control and the memory write
protect bits.
V
4
8
7
Ground
SS
V
14
Supply Voltage
CC
Reset Output. RESET is an active LOW open drain output which goes
active whenever Vcc falls below the minimum Vcc sense level. It will
remain active until Vcc rises above the minimum Vcc sense level for
800ms. RESET goes active if the Watchdog Timer is enabled and CS
remains either HIGH or LOW longer than the selectable Watchdog time-out
period. A falling edge of CS will reset the Watchdog Timer. RESET goes
active on power up at 1V and remains active for 800ms after the power
supply stabilizes.
7
13
RESET
NC
3-5,10-12
No internal connections
PIN CONFIGURATION
14-LEAD TSSOP
X51638
8-LEAD SOIC/PDIP
X51638
V
1
2
3
4
5
6
7
14
13
12
11
10
9
CS
SO
NC
CC
RESET
NC
V
1
2
3
4
8
7
6
5
CS
SO
WP
CC
RESET
SCK
SI
NC
NC
WP
NC
NC
V
SS
SCK
SI
V
SS
8
2
ETC [ ETC ]
