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S-93C46B_1 Datasheet, PDF (21/50 Pages) Seiko Instruments Inc – 3-WIRE SERIAL E2PROM
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Rev.7.0_00
3-WIRE SERIAL E2PROM
S-93C46B/56B/66B
„ 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-93C46B/56B/66B 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 23 Connection of 3-Wire Interface”).
CPU
S-93C46B/56B/66B
SIO
DI
DO
R : 10 to 100 kΩ
Figure 23 Connection of 3-Wire Interface
„ I/O Pin
1. Connection of input pins
All the input pins of the S-93C46B/56B/66B employ a CMOS structure, so design the equipment so that high
impedance will not be input while the S-93C46B/56B/66B 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-93C46B/56B/66B. 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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