S93L76A Datasheet, PDF (15/37 Pages) Seiko Instruments Inc – LOW VOLTAGE OPERATION 3-WIRE SERIAL E2PROM

Rev.6.0_02
LOW VOLTAGE OPERATION 3-WIRE SERIAL E²PROM
S-93L76A
 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-93L76A 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-93L76A
SIO
DI
DO
R: 10 kΩ to 100 kΩ
Figure 13 Connection of 3-Wire Interface
 Input Pin and Output Pin
1. Connection of input pins
All the input pins of the S-93L76A have the CMOS structure. Do not set these pins in high impedance during
operation when you design. Especially, set the CS pin to “L” at power-on, power-off, and during standby. The error
write does not occur as long as the CS pin is “L”. Set the CS pin to GND via a resistor (the pull-down resistor of 10 kΩ
to 100 kΩ).
To prevent the error for sure, it is recommended to use equivalent pull-down resistors for input pins other than the CS
pin.
2. Equivalent circuit of input pin and output pin
The following shows the equivalent circuits of input pins of the S-93L76A. 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.
15