Texas Instruments LM25066APSQ/NOPB

Overview

LM25066APSQ/NOPB from Texas Instruments is a PMBus™-compliant system power management and protection IC for hot-swap control and real-time telemetry. It operates from 2.9 V to 17 V input, delivers ±1% current measurement accuracy and ±2% input power accuracy over temperature, and integrates programmable 25-mV/46-mV current limiting, circuit breaker protection, and remote diode temperature sensing - deployed in server backplane power distribution systems.

For engineers reviewing the LM25066APSQ/NOPB datasheet, LM25066APSQ/NOPB pinout, LM25066APSQ/NOPB application, or LM25066APSQ/NOPB equivalent, key selection criteria include its 24-pin WQFN package, SMBus/I²C interface with PMBus command support, configurable UVLO/OVLO thresholds with hysteresis, true input power averaging via simultaneous VIN/IIN sampling, and black-box telemetry capture triggered by WARN/FAULT events.

Technical Context

The LM25066APSQ/NOPB implements a dedicated hot-swap architecture with fast-acting current limiting and a programmable circuit breaker that trips at 1.8× or 3.6× the selected overcurrent threshold. Its analog front-end performs synchronized 12-bit sampling of VIN, IIN, VOUT, and VAUX at 1 kHz, enabling accurate real-time power calculation (PIN = VIN × IIN) and configurable averaging over intervals from 1 ms to 4 s.

Control logic includes independent UVLO/EN and OVLO pins with 23-µA hysteresis current sources, a TIMER pin for setting insertion delay and fault timeout, and SMBus-alert (SMBA) signaling for asynchronous fault notification. The device supports remote MOSFET temperature monitoring via an external diode connected to the DIODE pin and provides a precision 2.73-V internal reference (VREF) for ADC calibration.

Key Specifications

Pinout & Package

LM25066APSQ/NOPB uses a 24-pin WQFN package (5.0 mm × 4.0 mm) with an exposed thermal pad soldered to PCB ground for optimal thermal performance. Pin functions are defined per TI SNVS700G datasheet Rev G.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar hot-swap and power telemetry applications.

Compared with LM25066IY/NOPB, LM25066APSQ/NOPB trades 0.5% current accuracy for lower cost and identical functionality in most server power applications; versus TPS2491PWR, it adds full PMBus telemetry and programmability at the expense of analog simplicity and footprint size.

Availability

LM25066APSQ/NOPB is available at Aetrix Electronics and suitable for server backplane systems, telecom power distribution, solid-state circuit breakers, and industrial rack power systems requiring stable component supply, long-term lifecycle support, and traceable sourcing.

Supply support for LM25066APSQ/NOPB 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 power IC design.

The LM25066A product line targets intelligent power distribution in computing and communications infrastructure, delivering integrated hot-swap control, precision telemetry, and PMBus-based system management in compact WQFN packages.

FAQ

What is the primary function of the LM25066APSQ/NOPB in a power system?

The LM25066APSQ/NOPB serves as a PMBus-compliant hot-swap controller and power telemetry IC. It protects downstream circuits during live insertion, limits inrush and steady-state current, monitors real-time voltage, current, power, and temperature, and reports data via SMBus. Its core role is enabling intelligent, host-managed DC power distribution - especially in server and telecom backplanes where reliability and visibility are critical. The LM25066APSQ/NOPB achieves this with integrated analog sensing, 12-bit ADCs, and full PMBus v1.2 command support.

How does the LM25066APSQ/NOPB achieve accurate input power measurement?

The LM25066APSQ/NOPB achieves ±2% input power (PIN) accuracy by simultaneously sampling VIN and IIN using synchronized 12-bit ADCs, then computing their product in real time. This eliminates phase-induced error common in sequential sampling methods. Averaging over programmable intervals (1 ms to 4 s) further reduces noise. The LM25066APSQ/NOPB also uses its internal 2.73-V reference (VREF) for ADC calibration and supports true RMS-like power calculation even under dynamic load transients - making it suitable for energy accounting in server power supplies.

Can the LM25066APSQ/NOPB replace a discrete hot-swap controller and separate power monitor?

Yes - the LM25066APSQ/NOPB integrates both functions into a single 24-pin WQFN device. It replaces traditional discrete solutions comprising a hot-swap controller (e.g., TPS2375x), current-sense amplifier, ADC, and microcontroller-based telemetry engine. By embedding PMBus firmware, synchronous sampling, black-box logging, and configurable protection (UVLO/OVLO/circuit breaker), the LM25066APSQ/NOPB reduces BOM count, PCB area, and firmware development effort. However, it requires SMBus host support - unlike analog-only alternatives.

What is the purpose of the TIMER pin on the LM25066APSQ/NOPB?

The TIMER pin on the LM25066APSQ/NOPB sets three critical timing parameters via an external capacitor: insertion delay (soft-start duration), fault timeout period (time before GATE disables after overcurrent detection), and retry interval (if RETRY = GND). Its dual-threshold comparator (1.07 V low, 1.7 V high) controls state transitions in the internal timing FSM. For example, a 100 nF capacitor yields ~140 ms insertion delay and ~8.3 ms fault timeout - enabling precise tuning of power-up sequencing and short-circuit response without external timers or microcontrollers. This is integral to the LM25066APSQ/NOPB's autonomous protection behavior.

Does the LM25066APSQ/NOPB support remote temperature monitoring, and how is it implemented?

Yes - the LM25066APSQ/NOPB supports remote temperature monitoring via its DIODE pin, which sources a programmable current (250–300 µA high level, 9.4 µA low level) into an external NPN transistor configured as a diode. The resulting forward voltage is measured by an internal 9-bit ADC, enabling junction temperature estimation of the external MOSFET or other thermally coupled components. Accuracy ranges from ±2°C to ±10°C depending on diode matching and layout. This feature is distinct from on-die temperature sensing and allows the LM25066APSQ/NOPB to protect against MOSFET thermal runaway - a key requirement in high-power hot-swap applications.