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An IMPORTANT NOTICE at the end of this data sheet addresses availability, warranty, changes, use in safety-critical applications,

intellectual property matters and other important disclaimers. PRODUCTION DATA.

TMS3705

SCBS881C – JANUARY 2010 – REVISED APRIL 2016

TMS3705 Transponder Base Station IC

1

Device Overview

1

1.1

Features

1

• Base Station IC for TI-RFid™ RF Identification

Systems

• Drives Antenna

• Sends Modulated Data to Antenna

• Detects and Demodulates Transponder Response

(FSK)

• Short-Circuit Protection

• Diagnosis

• Sleep-Mode Supply Current: 0.2 mA

• Designed for Automotive Requirements

• 16-Pin SOIC (D) Package

1.2

Applications

•

Car Access

•

Immobilization

•

Building Access

•

Livestock Reader

1.3

Description

The TMS3705 transponder base station IC is used to drive the antenna of a TI-RFid transponder system,

to send data modulated on the antenna signal, and to detect and demodulate the response of the

transponder. The response of the transponder is a frequency shift keyed (FSK) signal. The high or low bits

are coded in two different high-frequency signals (134.2 kHz for low bits and 123 kHz for high bits,

nominal). The transponder induces these signals in the antenna coil according an internally stored code.

The energy that the transponder needs to send out the data is stored in a charge capacitor in the

transponder. The antenna field charges this capacitor in a preceding charge phase. The IC has an

interface to an external microcontroller.

There are two configurations for the clock supply to both the microcontroller and the base station IC:

1. The microcontroller and base station IC are supplied with a clock signal derived from only one

resonator: The resonator is attached to the microcontroller. The base station IC is supplied with a clock

signal driven by the digital clock output of the microcontroller. The clock frequency is either 4 MHz or

2 MHz, depending on the selected microcontroller type.

2. The microcontroller and the base station each have their own resonator.

The base station IC has an on-chip PLL that generates a clock frequency of 16 MHz for internal clock

supply only. The TMS3705BDRG4 and TMS3705DDRG4 are optimized for higher communication data

rates and, therefore, work without frequency measurement during the write phase.

(1)

For the most current part, package, and ordering information for all available devices, see the Package

Option Addendum in Section 8, or see the TI website at www.ti.com.

(2)

The sizes shown here are approximations. For the package dimensions with tolerances, see the

Mechanical Data in Section 8.

PART NUMBER

PACKAGE

TMS3705A1DRG4

SOIC (16)

9.9 mm × 3.91 mm

TMS3705BDRG4

SOIC (16)

9.9 mm × 3.91 mm

TMS3705DDRG4

SOIC (16)

9.9 mm × 3.91 mm