2-WIRE CMOS SERIAL E2PROM FOR DIMM SERIAL PRESENCE DETECT

S-34C02A

Seiko Instruments Inc.

21

Using S-34C02A

1. SDA I/O pin and SCL input pin

In consideration of I

resister of 1 to 5 k

Ω.

The S-34C02A cannot transmit normally without using a pull-up resistor.

*1.

In the case that the SCL input pin of the S-34C02A is connected to the tri-state output pin in the master device,

connect the SCL pin with a pull-up resistor as well in order not to set the SCL input pin in high impedance. This

prevents the S-34C02A from error caused by an uncertain output (high impedance) from the tri-state pin when

resetting the master device during the voltage drop.

2. Equivalent circuit of I/O pin

Each input pin (A0, A1, A2, WP) of the S-34C02A has a built-in pull-down register. The SDA line has an open-drain

output. The followings are equivalent circuits of the pins.

SCL

Figure 19 SCL Pin

SDA

Figure 20 SDA Pin