TMS3705
The Texas Instruments TMS3705 is an reader IC, with N/A (base station/reader IC, not a transponder), operating at 134.2 kHz (nominal); FSK demodulation at 134.2 kHz (low bits) and 123 kHz (high bits), under TI-RFid HDX (Half-Duplex) FSK.
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
Standards & Compliance
Frequently Asked Questions
What frequency does the TMS3705 reader IC operate at?
The TMS3705 operates at a nominal frequency of 134.2 kHz and demodulates FSK responses at 134.2 kHz (low bits) and 123 kHz (high bits) from HDX transponders.
What interface does the TMS3705 use to communicate with a microcontroller?
The TMS3705 uses an SCI (Serial Communications Interface) with SCIO output pin to communicate with an external microcontroller, supporting both asynchronous and synchronous modes.
Is the TMS3705 a transponder or a reader IC?
The TMS3705 is a base station/reader IC, not a transponder. It drives an external antenna to power and communicate with passive HDX transponders in TI-RFid systems.
What transponder types does the TMS3705 support?
The TMS3705 supports TI-RFid HDX transponders. Variants TMS3705DDRQ1/GDRQ1 support AES-encrypted transponders, while TMS3705EDRQ1/FDRQ1 are optimized for DST40/80 and MPT transponders.
What is the sleep mode current consumption of the TMS3705?
The TMS3705 has a low-power sleep mode with a current consumption of approximately 0.2 mA, making it suitable for battery-powered or energy-conscious automotive applications.
Is the TMS3705 qualified for automotive use?
Yes, the TMS3705 variants with Q1 suffix (e.g., TMS3705DDRQ1) are qualified for automotive applications and meet automotive-grade quality and temperature requirements.
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