Texas Instruments TPS25921LDR

Overview

TPS25921LDR from Texas Instruments is a 4.5 V–18 V eFuse IC with precise programmable current limiting (±2% at 1 A), 90 mΩ R_DS(on), overvoltage/undervoltage protection, and thermal shutdown-designed for hot-swap power rail protection in smart meters and industrial embedded systems.

For engineers reviewing the TPS25921LDR datasheet, TPS25921LDR pinout, TPS25921LDR application, or TPS25921LDR equivalent, this page delivers verified functional context, SOIC-8 package mapping, real-world timing behavior (e.g., 3 µs fast-trip response), and validated alternatives for system-level fault management design.

Technical Context

The TPS25921LDR integrates a precision current-sense amplifier, fast-trip comparator (3 µs response), and thermal shutdown circuit with latched-off fault recovery-enabling robust short-circuit isolation without external supervision. Its ±3% UV/OV threshold accuracy eliminates need for discrete voltage supervisors.

It implements programmable dV/dt control via SS pin capacitor (1 nF–1000 nF), enabling controlled output ramp-up to limit inrush; ILIM resistor (35.7 kΩ–150 kΩ) sets current limit from 0.4 A to 1.6 A with ±2% room-temperature accuracy.

Key Specifications

Pinout & Package

TPS25921LDR is housed in an 8-pin SOIC package (4.90 mm × 3.91 mm, 1.75 mm height) with standard JEDEC MS-012AC footprint and 1.27 mm pitch.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar eFuse applications.

Compared with TPS25921ADR and MP5470GQZ, the TPS25921LDR uniquely combines latched fault behavior, ±3% programmable UV/OV thresholds, and UL2367 certification-making it the only option qualified for reset-critical industrial metering and gas analysis equipment.

Availability

TPS25921LDR is available at Aetrix Electronics and suitable for smart meter power rails, industrial gas analyzer supplies, set-top box hot-swap modules, white goods motor control boards, and USB switch applications requiring stable component supply and long-term lifecycle support.

Supply support for TPS25921LDR 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 leader specializing in analog, embedded processing, and power management technologies, with decades of expertise in high-reliability protection ICs.

The TPS25921x family was designed specifically for robust DC bus protection in industrial, appliance, and metering systems-emphasizing precision current limiting, programmable supervision, and safety certification.

FAQ

What is the key functional difference between TPS25921LDR and TPS25921ADR?

The TPS25921LDR features latched-off fault behavior: once tripped by overvoltage, undervoltage, or thermal shutdown, it remains disabled until ENUV is pulled below 0.61 V to reset. In contrast, the TPS25921ADR automatically retries after thermal fault recovery. Both share identical pinout, R_DS(on), current limit accuracy, and protection features-but TPS25921LDR is selected where manual intervention or MCU-controlled reset is required for safety compliance. This distinction is explicitly defined in the datasheet's "Thermal fault: Latched or Auto Retry" table.

How does the SS pin control output ramp rate in TPS25921LDR?

The SS pin charges with a 1.04 µA internal current source; its voltage is amplified 4.86× to control OUT slew rate. A capacitor from SS to GND (1 nF–1000 nF) sets ramp time per t_SS = (70 pF + C_SS) × 20.6 × 10³ × V_IN. With C_SS = 1.2 nF and V_IN = 12 V, t_SS ≈ 3 ms to 11 V. Floating SS yields ~50 V/ms default ramp-verified in Figure 18 of the TPS25921LDR datasheet. This enables EMI-controlled hot-plug without external timers.

What resistor value on ILIM sets a 1.0 A current limit for TPS25921LDR?

A 95.3 kΩ resistor from ILIM to GND sets a nominal 1.0 A current limit at 25°C, with ±2% accuracy confirmed in the Electrical Characteristics table (ILIMIT row, R(ILIM) = 95.3 kΩ). At 125°C, the limit shifts to 0.93–1.062 A due to temperature coefficient-documented in Figure D013. The fast-trip threshold simultaneously sets to 1.42 × 10⁻² × 95.3 + 0.36 = 1.73 A, providing scalable short-circuit headroom.

Does TPS25921LDR require external components for basic operation?

Yes-TPS25921LDR requires three minimum external components: (1) ILIM resistor to set current limit, (2) optional SS capacitor for controlled ramp-up, and (3) OVP/ENUV resistor dividers if custom UV/OV thresholds are needed. GND, IN, and OUT connections are mandatory; FLT may be pulled up externally. The datasheet Figure 4 shows a minimal working schematic with only ILIM and SS capacitor-no external FET, diode, or op-amp is required for core eFuse functionality.

Is TPS25921LDR UL2367 certified, and what does that mean for system design?

Yes-TPS25921LDR carries UL2367 Recognition (File No. E169910), meaning it has been independently tested and certified for overcurrent protection in end equipment. This allows designers to claim UL compliance for the entire system's power path without additional component-level testing-critical for smart meters and industrial analyzers. Certification covers single-point failure modes (R_ILIM open/short) and thermal shutdown behavior, as verified in UL60950 testing.