TMS37157_11 Datasheet, PDF (9/47 Pages) Texas Instruments – PASSIVE LOW FREQUENCY INTERFACE DEVICE WITH EEPROM AND 134.2 kHz TRANSPONDER INTERFACE

TMS37157
www.ti.com
SWRS083A – SEPTEMBER 2009 – REVISED NOVEMBER 2009
BLOCK DESCRIPTION
Analog Front End
The Analog Front End implements all of the analog functions needed to support the TMS37157 transponder
functions. It enables reception and transmission of LF signals when the transponder is active, and rectifies
incoming LF energy and stores it in an external charge capacitor, to power the device.
The Analog Front End also contains the capacitor array used to trim the transponder's resonance circuit and a
clock regenerator function, which is able to recover the clock from an incoming signal so it can be used by the
transponder functions.
Control Unit
DST Transponder
The transponder implemented in the TMS37157 is compatible with Texas Instruments' DST ("Digital Signature
Transponder") transponder. In addition the TMS37157 provides additional Memory for customer use.
CRC Calculation
A hardware cyclic redudancy check calculation engine is implemented in the Control Unit to provide error
detection.
Memory Access
The Control Unit interfaces to the on-chip EEPROM. During power-up, the Control Unit reads the configuration
parameters stored in the EEPROM and initializes the TMS37157 circuitry accordingly, and at various times
during device operation it can read EEPROM data and provide it, for example, to a microcontroller.
SPI Interface
The Control Unit provides an SPI interface that allows it to communicate with a microcontroller. Via this interface,
for example, the microcontroller is able to access the contents of the TMS37157 EEPROM.
Test Interface
The Control Unit provides a test interface that allows customers to trim the LF antenna's resonance circuit.
Transponder and User Memory
The Transponder Memory comprises a total of 126 bytes, organized in pages. Memory space is apportioned as
follows:
• User Data 121 bytes
• Serial Number + Manufactorer Code 4 bytes
• Selective Address 1 byte
Copyright © 2009, Texas Instruments Incorporated
Product Folder Link(s): TMS37157
Submit Documentation Feedback
9