S93C76A Datasheet, PDF (15/28 Pages) Seiko Instruments Inc – FOR AUTOMOTIVE 105C OPERATION

Rev.3.1_00
FOR AUTOMOTIVE 105°C OPERATION 3-WIRE SERIAL E²PROM
S-93C76A H Series
 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 kΩ 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 kΩ to 100 kΩ
Figure 13 Connection of 3-Wire Interface
 I/O Pin
1. Connection of input pins
All the input pins of the S-93C76A employ a CMOS 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 kΩ 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. Equivalent circuit of input and output pin
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.
Seiko Instruments Inc.
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