Texas Instruments LP3971SQ-B410/NOPB

Overview

LP3971SQ-B410/NOPB from Texas Instruments is a programmable power management unit (PMU) for advanced application processors, integrating three 1.6A buck regulators, six LDOs (including 30 mA RTC LDO), I²C-controlled backup battery charger, and dual GPIOs in a 40-pin 5×5 mm WQFN package. It delivers ±3% output voltage accuracy, up to 95% buck efficiency, and supports dynamic voltage management for PDA phones and smart phones.

For engineers reviewing the LP3971SQ-B410/NOPB datasheet, LP3971SQ-B410/NOPB pinout, LP3971SQ-B410/NOPB application, or LP3971SQ-B410/NOPB equivalent, key selection criteria include I²C-programmable VOUT ranges (0.725–3.3 V for bucks; 1.0–3.3 V for LDOs), thermal shutdown at 160°C, 100 mV typical dropout for LDO_RTC, and synchronized 10.4–15.6 MHz buck operation.

Technical Context

The LP3971SQ-B410/NOPB implements three independent synchronous buck converters with internal 240 mΩ PFET and 200 mΩ NFET switches, operating at 2 MHz nominal frequency or externally synchronized via SYNC pin. Each buck supports programmable output from 0.725 V to 3.3 V with ±3% accuracy and delivers up to 1.6 A continuous current.

Six LDOs are integrated: LDO_RTC (30 mA, 2.8 V default, 100 mV dropout), LDO1–LDO5 (300/150/150/150/370 mA max), all featuring ±3% output accuracy, 45 dB PSRR at 10 kHz, and programmable VOUT from 1.0 V to 3.3 V. The backup battery charger provides 150/300/370 mA selectable charge current with automatic main-to-backup switchover at 2.8 V.

Key Specifications

Pinout & Package

LP3971SQ-B410/NOPB uses a 40-pin WQFN package (RSB0040A, 5×5 mm, 0.4 mm pitch) with exposed thermal pad. Pin 1 is marked by a circle on top view; BGND1,2,3 and PGND1,2,3 provide dedicated analog and power ground returns for noise isolation.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar power management unit applications.

Compared with TPS65023RSBR and MAX8649ETE+, LP3971SQ-B410/NOPB uniquely combines coin-cell-optimized backup charging, RTC LDO tracking, and 1.6 A buck capability in a single 5×5 mm WQFN-critical for space-constrained, battery-backed portable processors.

Availability

LP3971SQ-B410/NOPB is available at Aetrix Electronics and suitable for smartphone baseband power, PDA application processor rail, digital camera sensor & codec, and portable media player system requiring stable component supply and long-lifecycle support.

Supply support for LP3971SQ-B410/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 over 90 years of innovation.

The LP3971 product line was designed specifically for advanced application processors in low-power handheld devices, integrating multi-rail DC/DC, LDO, and battery management functions into a single PMU IC.

FAQ

What is the default output voltage configuration for LP3971SQ-B410/NOPB?

The LP3971SQ-B410/NOPB has factory-programmed default voltages: LDO_RTC = 2.8 V, LDO1 = 3.3 V (SYS_EN enabled), LDO2 = 3.0 V, LDO3 = 3.0 V, LDO4 = 1.3 V (PWR_EN enabled), LDO5 = 1.1 V (PWR_EN enabled), BUCK1 = 1.4 V (PWR_EN enabled), BUCK2 = 3.0 V (SYS_EN enabled), and BUCK3 = 1.8 V (SYS_EN enabled). These values are confirmed in the Default Voltage Options table of the SNVS432V datasheet.

Does LP3971SQ-B410/NOPB support I²C clock stretching or multi-master arbitration?

No, the LP3971SQ-B410/NOPB implements a standard I²C-compatible interface without clock stretching or multi-master arbitration support. It operates as a slave device with fixed 7-bit address (0x48 or 0x49 depending on ADDR pin), and timing complies with standard-mode (100 kHz) and fast-mode (400 kHz) specifications per the SNVS432V datasheet Section 8.5.

How does the LP3971SQ-B410/NOPB handle main battery failure detection and RTC backup switchover?

The LP3971SQ-B410/NOPB monitors main battery voltage via internal circuitry and asserts nBATT_FLT when VIN drops below 2.8 V (typical threshold). Simultaneously, it automatically disconnects the RTC LDO from the main battery and connects it to the backup coin cell. Switchover hysteresis is ~300 mV, so reconnection to main battery occurs only when VIN rises above 3.1 V.

Can LP3971SQ-B410/NOPB's buck regulators operate in forced PWM mode, and what is the minimum load for stable operation?

Yes, LP3971SQ-B410/NOPB buck regulators support forced PWM mode via I²C register control, eliminating mode transitions during light loads. Stable operation is guaranteed down to 1 mA load per buck stage, as validated in Figures 9–10 (efficiency vs. load) and Figure 14 (load transient response) of the SNVS432V datasheet.

What thermal management features does LP3971SQ-B410/NOPB include, and what is its maximum junction temperature?

LP3971SQ-B410/NOPB includes thermal overload protection that triggers shutdown at 160°C junction temperature, with 20°C hysteresis for recovery. Its θJA is 25°C/W (JEDEC JESD51-7, 4-layer board), and maximum power dissipation at TA = 70°C is 2.2 W. The exposed thermal pad must be soldered to PCB copper for effective heat transfer.