S93C86B-H Datasheet, PDF (18/28 Pages) Seiko Instruments Inc – FOR AUTOMOTIVE OPERATION 3-WIRE SERIAL E2PROM

FOR AUTOMOTIVE 105°C OPERATION 3-WIRE SERIAL E²PROM
S-93C86B H Series
Rev.2.1_02
 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-
93C86B 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 Connection of 3-Wire Interface”).
CPU
S-93C86B
SIO
DI
DO
R: 10 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-93C86B employ a CMOS structure, so design the equipment so that high impedance will not be
input while the S-93C86B 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. Equivalent circuit of input and output pin
The following shows the equivalent circuits of input pins of the S-93C86B. 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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