TMS3705
HDX LF base station IC, automotive immobilizer
Full Specifications
| Manufacturer | Texas Instruments |
|---|---|
| Frequency Category | LF 125 kHz |
| Frequency | 134.2 kHz (nominal); FSK demodulation at 134.2 kHz (low bits) and 123 kHz (high bits) |
| Protocol | TI-RFid HDX (Half-Duplex), FSK |
| Memory | N/A (base station/reader IC, not a transponder) |
| Interface | Antenna driver outputs (ANT1, ANT2 full-bridge), SCI (serial) interface to microcontroller (SCIO output), control inputs (TXCT, F_SEL), oscillator pins (OSC1, OSC2) |
| Temperature Range | -40°C to +85°C |
| Form Factor | 16-pin SOIC (D), 9.9 mm × 3.91 mm |
| Security | N/A (base station IC; compatible with AES transponders for TMS3705DDRQ1/GDRQ1 variants; TMS3705EDRQ1/FDRQ1 for DST/MPT transponders) |
Engineering Brief
The TMS3705 is a low-frequency (134.2 kHz) base station/reader IC for TI-RFid HDX transponder systems, designed for automotive and access-control applications. It drives an external antenna via a full-bridge output, sends modulated data to transponders, and demodulates FSK responses (134.2 kHz / 123 kHz). The IC includes an on-chip PLL (4 MHz or 2 MHz crystal input, 16 MHz internal clock), programmable frequency divider, digital demodulator, diagnosis, overcurrent protection, and low-power sleep mode (0.2 mA). It interfaces with an external microcontroller via SCI (asynchronous or synchronous mode) and control pins, and is qualified for automotive use (Q1). Variants TMS3705DDRQ1/GDRQ1 support AES transponders; TMS3705EDRQ1/FDRQ1 are optimized for DST40/80 and MPT transponders.
Typical Applications
- Automotive car access systems
- Vehicle immobilizer readers
- Building access control readers
- Livestock RFID readers
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