HT672B -- 13.56MHz RFID Transponder

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 reserved for customer) in the chip, with a 8-bits checksum code. The effective detection range for a small sized antenna is 2cm~10cm which is dependent on antenna format & 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. Implementing Holtek's advanced OTP and low power technology, 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 program the device using the specified programmer supplied by Holtek. The pre-programmed ICs are also available upon customer's request.