S-93A46A SII [Seiko Instruments Inc], S-93A46A Datasheet - Page 19

• Manufacturer Part Number: S-93A46A
• Description: CMOS SERIAL E2PROM
• Manufacturer: SII [Seiko Instruments Inc]

Rev.2.1
3-Wire Interface (Direct Connection between DI and DO)
I/O Pins
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-93A46A/56A/66A via a resistor (10 k
the CPU takes precedence in being input to the DI pin (Refer to “ Figure 18 Connection of 3-Wire
Interface ”).
1. Connection of Input Pins
2. Input and Output Pin Equivalent Circuits
All the input pins of the S-93A46A/56A/66A employ a CMOS structure, so design the equipment so that
high impedance will not be input while the S-93A46A/56A/66A 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 k
pull-down resistor). To prevent malfunction, it is recommended to use equivalent pull-down resistors for
pins other than the CS pin.
The following shows the equivalent circuits of input pins of the S-93A46A/56A/66A. 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.
_00
Figure 18 Connection of 3-Wire Interface
CPU
SIO
Seiko Instruments Inc.
R: 10 k to 100 k
S-93A46A/56A/66A
DI
DO
to 100 k ) so that the data output from
CMOS SERIAL E
S-93A46A/56A/66A
2
to 100 k
PROM
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