SR176

2/5

SUMMARY DESCRIPTION

The SR176 is a contactless memory, powered by

an externally transmitted radio wave. It contains

176 bits of user EEPROM, fabricated with STMi-

croelectronics CMOS technology. The memory is

organized as 16 blocks of 16 bits, of which 11

blocks are user accessible.

The SR176 is accessed via the 13.56MHz carrier.

Incoming data are demodulated and decoded

from the received Amplitude Shift Keying modula-

tion signal (ASK). The modulation index of this sig-

nal is 10%. Outgoing data are generated by load

variation using Bit Phase Shift Keying (BPSK) of a

847kHz subcarrier. The Data transfer rate be-

tween the SR176 and the reader is 106kbit/s in

both reception and emission modes.

The SR176 follows the ISO 14443 part 2 type B

recommendation for radio frequency power and

signal interface.

Figure 2. Logic Diagram

The SR176 is principally designed for short range

applications, such as in object identification, that

need a low cost and non-reusable product. The

SR176 does not include any anti-collision mecha-

nism, but does include a simple selection mecha-

nism to cope with cases where more than one tag

is present, within the range of the Reader, at the

any one time.

Table 1. Signal Names

The SR176 contactless EEPROM offers read and

write random access in block mode. One block is

composed by 16 bits. The device has an instruc-

tion set containing seven commands:

s

READ_BLOCK

s

WRITE_BLOCK

s

INITIATE

s

SELECT

s

COMPLETION

s

PROTECT_BLOCK

s

GET_PROTECTION.

The SR176 is divided into two major areas: the

unique identifier (UID) and the User EEPROM.

The UID is a 64-bit unique identifier written by ST

during product manufacturing. The User EEPROM

is divided into areas which can be write-protected

so that they behave as ROM. The write protection

is activated using an OTP lock bits register. It is

possible to program the SR176 4-bit chip_ID used

by the SELECT command. Its default value is fixed

up to sixteen SRIX4Ks can be selected individual-

ly.

AI04995

AC1

SR176

AC0

Power

Supply

Regulator

BPSK

Load

Modulator

ASK

Demodulator

176 bit

User

EEPROM

AC1

Antenna Coil

AC0

Antenna Coil