Integrated Silicon Solution, Inc. — 1-800-379-4774

3

REV. A

11/01/01

IS23SC4418

IS23SC4428

PIN NAMES

Pin

Card Contact

Symbol

Description

1

C1

Vcc

Supply Voltage

2

C2

RST

Reset

3

C3

CLK

Serial Clock

4

C4

NC

No Connect

5

C5

GND

Ground

6

C6

NC

No Connect

7

C7

I/O

Serial Data I/O (open drain)

8

C8

NC

No Connect

C1

C2

C3

C4

C5

C6

C7

C8

Vcc

RST

CLK

NC

GND

NC

I/O

NC

PIN DESCRIPTIONS

Symbol

Type

Card Contact

Name and Function

Vcc

C1

Supply Voltage

RST

C2

Reset: The device reset pin (RST) is used to take the device out of the power-on

reset state (POR). When the operating power is first applied to Vcc, the device goes

into POR state. The POR state can be terminated by RST in this sequence: bring

RST from 0 to 1 and then change CLK from 0 to 1 (See Figure 3). This reset

operation terminates any active command operation. After the POR state has been

terminated, a read operation must be performed before any data can be erased or

written. Also, IS23SC4418/28 meets the ISO 7816 specification on Answer to Reset

function. The Answer to Reset can be invoked by performing the following steps:

1) RST goes from 0 to 1; 2) CLK pulse is applied; 3) RST changes from 1 to 0.

If these steps are performed correctly, the device will set the address counter to 0

and the first data bit at byte address 0 will appear on the output (I/O). By continuing

to send pulses at CLK, the contents of the following byte addresses can be read out

of the device. (See Figure 3)

In normal operation, RST controls the data input and output directions. When

sending data/command to the device, RST is set to 1. When reading data/PSC

verification output from the device, RST is set to 0. (See Figure 4)

CLK

C3

Serial Clock: This is the device data clock pin. It is used to clock data bits into and

out of the device.

NC

C4, C6, C8

No Connect

GND

C5

Ground

I/O

C7

Serial Data Input and Output: This pin is where data is shifted in and out of the

device.

Figure 2. Pin Configuration