HT672B

13.56MHz RFID Transponder

Block Diagram

Rev. 1.10

1

November 23, 2004

Features

Applications

General Description

The HT672B is a RF transponder IC operating with

13.56MHz RF carrier, which provides a low cost

batteryless transponder solution with the addition of

merely an external inductor. The inductor and internal

capacitor form a LC tank which inducing voltage from

the radiated 13.56MHz carrier signal generated from the

reader antenna. HT672B has a built-in low power RC

oscillator which is activated if the induced carrier field

strength is high enough to supply the operating current

and the response signal(pre-programmed in the OTP

memory) is serial transmitted out. The response data is

transmitted using PWM/ASK modulation. Modulation of

13.56MHz is accomplished by damping the LC tank with

a fixed baud rate.

The transmission information is stored in 40 bits. One

Time Programmable memory (OTP) (up to 32 bits re-

served for customer) in the chip, with a 8-bits checksum

code. The effective detection range for a small sized an-

tenna is 2cm~10cm which is dependent on antenna for-

mat & reader design. The larger the antenna loop used

the longer the detection range. It is advisable to use

larger antenna to attain a 15cm detection range. Imple-

menting Holtek

¢s advanced OTP and low power tech-

nology, HT672B offers a very cost effective solution for

RF contactless detection system. A code area of

32-bits(max.) wide is provided so customers can pro-

gram the device using the specified programmer sup-

plied by Holtek. The pre-programmed Ics are also

available upon customer

¢s request.

V P P

C L K

H F

H F 1

V D D

V S S

P W M / A S K

M o d u l a t o r

S h i f t

R e g i s t e r

D a t a

S y s t e m

C l o c k

G e n e r a t o r

V C C L i m i t e r

a n d

R F L i m i t e r

D a t a

P r o c e s s i n g

F r e q u e n c y

D r i v e r f / 4

T e s t B l o c k