Texas Instruments TMS37157IRSARG4

Overview

TMS37157IRSARG4 from Texas Instruments is a passive low-frequency transponder interface IC with integrated 121-byte EEPROM, 134.2 kHz HDX communication, ultra-low-power operation (60 nA in power-down mode), and SPI/microcontroller co-processor capability for batteryless sensor and configuration memory applications.

For engineers reviewing the TMS37157IRSARG4 datasheet, TMS37157IRSARG4 pinout, TMS37157IRSARG4 application, or TMS37157IRSARG4 equivalent, this page delivers verified electrical parameters, LF transponder timing constraints, SPI interface behavior, push-button wake-up logic, and EEPROM lock/protect architecture - all confirmed from TI's SWRS083A datasheet and official ordering documentation.

Technical Context

The TMS37157IRSARG4 implements a DST-compatible 134.2 kHz half-duplex transponder front end with on-chip resonance trimming (0–85.9 pF total capacitance), RF limiter (10.5–14 V), and clock regeneration from incoming LF field. It supports PPM-encoded downlink (ASk) and FSK uplink (8 kbit/s max) without battery support.

Its control unit manages dual power domains: RF-field-derived VCL (5.75–6.5 V activation threshold) powers transponder functions and charge capacitor CL (220 nF typical), while VBAT (2–3.6 V) supplies SPI and microcontroller interface. The NPOR open-drain reset output and BUSY handshaking signal coordinate deterministic SPI access during transponder activity.

Key Specifications

Pinout & Package

Package: 4 mm × 4 mm, 0.6 mm pitch, 16-pin VQFN (RSA). Thermal pad exposed on underside for enhanced power dissipation in continuous transponder operation.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar passive LF transponder interface applications.

Compared with ATA5577M1600-TAQY and SL2S2201P, the TMS37157IRSARG4 uniquely combines 134.2 kHz batteryless operation, 121-byte programmable EEPROM, SPI co-processor interface, and push-button wake-up - making it the only option for autonomous, field-updatable, ultra-low-power sensor nodes requiring LF robustness.

Availability

TMS37157IRSARG4 is available at Aetrix Electronics and suitable for wireless sensor nodes, batteryless smart meters, remote control key fobs, and industrial asset tags requiring stable component supply across extended temperature ranges and long product lifecycles.

Supply support for TMS37157IRSARG4 includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

Texas Instruments is a global semiconductor company specializing in analog, embedded processing, and connectivity technologies, with leadership in low-power design and industrial-grade reliability.

The TMS37157IRSARG4 belongs to TI's passive RFID and sensor interface product line, engineered specifically for batteryless, energy-harvested systems requiring secure, field-updatable memory and robust 134.2 kHz communication in electrically noisy environments.

FAQ

What is the minimum RF field strength required to activate the TMS37157IRSARG4?

The TMS37157IRSARG4 requires a minimum short-circuit current of 0.64 mA at the transponder coil position when the operating quality factor Qop ≥30. This corresponds to an activation voltage of ≥5.75 V at the VCL pin, measured just before transponder response begins. Field strength must sustain this level for ≥20 ms charge time per TI SWRS083A specifications. The TMS37157IRSARG4 will not respond below this threshold to prevent false triggers in marginal RF conditions.

Can the TMS37157IRSARG4 operate without any battery connected?

Yes, the TMS37157IRSARG4 supports full batteryless operation: its EEPROM is readable and writable over the 134.2 kHz LF interface without VBAT, and the analog front end is powered entirely from harvested RF energy stored on the VCL capacitor. Battery connection (VBAT) is optional and only needed to power the SPI interface or enable VBATI-supplied microcontrollers during active sessions.

How does the selective addressing feature work in the TMS37157IRSARG4?

Selective addressing in the TMS37157IRSARG4 is enabled by writing any value other than 0xFF to byte 0 of Page 1. Once set, all subsequent Program, Lock, Protect, and Selective Read commands require inclusion of this 8-bit password in the command frame. The TMS37157IRSARG4 compares the received address against the stored value; mismatch halts command execution. This prevents unauthorized access in multi-tag environments and supports anti-collision protocols.

What is the purpose of the CLKAM pin on the TMS37157IRSARG4?

CLKAM (Clock from Antenna Module) outputs a clean, resonance-derived clock signal - either FRES (134.2 kHz) or FRES/4 (33.55 kHz) - to the connected microcontroller. Enabled via SPI command, this eliminates the need for a separate crystal oscillator or RC timing circuit. The TMS37157IRSARG4 generates CLKAM directly from the antenna LC tank, ensuring precise synchronization between reader and transponder timing without additional components.

Is the EEPROM memory in the TMS37157IRSARG4 lockable at the page level?

Yes, the TMS37157IRSARG4 supports irreversible page-level locking for all 126 bytes of transponder memory. Each page (e.g., Page 1, Page 2, Pages 8–15, Pages 40–55) has a dedicated lock bit that, once set via Lock Page command, permanently disables further writes to that page. Locked pages remain readable via LF or SPI. This ensures configuration constants, calibration data, or cryptographic keys remain tamper-proof throughout the device's operational life.