S-93C76A Datasheet, PDF (14/33 Pages) Seiko Instruments Inc – CMOS SERIAL E2PROM

CMOS SERIAL E²PROM
S-93C76A
Rev.3.2_00
„ 3-Wire Interface (Direct Connection between DI and DO)
There are two types of serial interface configurations: a 4-wire interface configured using the CS, SK, DI,
and DO pins, and a 3-wire interface that connects the DI input pin and DO output pin.
When the 3-wire interface is employed, a period in which the data output from the CPU and the data output
from the serial memory collide may occur, causing a malfunction. To prevent such a malfunction, connect
the DI and DO pins of the S-93C76A via a resistor (10 to 100 kΩ) so that the data output from the CPU
takes precedence in being input to the DI pin (refer to Figure 13).
CPU
S-93C76A
SIO
DI
DO
R: 10 to 100 kΩ
Figure 13 Connection of 3-Wire Interface
„ I/O Pins
1. Connection of input pins
All the input pins of the S-93C76A employ a C-MOS structure, so design the equipment so that high
impedance will not be input while the S-93C76A is operating. Especially, deselect the CS input (a low
level) when turning on/off power and during standby. When the CS pin is deselected (a low level),
incorrect data writing will not occur. Connect the CS pin to GND via a resistor (10 to 100 kΩ pull-down
resistor). To prevent malfunction, it is recommended to use equivalent pull-down resistors for pins other
than the CS pin.
2. Input and output pin equivalent circuits
The following shows the equivalent circuits of input pins of the S-93C76A. None of the input pins
incorporate pull-up and pull-down elements, so special care must be taken when designing to prevent a
floating status.
Output pins are high-level/low-level/high-impedance tri-state outputs. The TEST pin is disconnected
from the internal circuit by a switching transistor during normal operation. As long as the absolute
maximum rating is satisfied, the TEST pin and internal circuit will never be connected.
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Seiko Instruments Inc.