Texas Instruments LP3988IMF-3.3

Overview

LP3988IMF-3.3 from Texas Instruments is a micropower, ultra-low-dropout CMOS voltage regulator delivering 150 mA at fixed 3.3 V ±3.5% output, with integrated Power Good (PG) flag and logic-controlled enable. It operates from 2.5 V to 6 V input, achieves 80 mV typical dropout at full load, consumes ≤1 µA in shutdown, and targets space-constrained battery-powered RF subsystems such as GSM/CDMA handset power rails.

For engineers reviewing the LP3988IMF-3.3 datasheet, LP3988IMF-3.3 pinout, LP3988IMF-3.3 application, or LP3988IMF-3.3 equivalent, key selection considerations include its 100 µs typical turnon time, open-drain PG threshold accuracy (90–95% VOUT), ceramic-capacitor stability (1 µF min), −40°C to +125°C junction temperature range, and SOT-23-5 package compatibility with high-density portable PCB layouts.

Technical Context

The LP3988IMF-3.3 integrates a PMOS pass transistor with internal reference and error amplifier to maintain regulation across line (2.5–6 V) and load (0–150 mA) variations. Its PG circuitry uses dual hysteresis thresholds (VTHL = 90–95%, VTHH = 92–98% of VOUT) to detect output faults with 10 µs typical response, while EN control enables precise system-level power sequencing.

Designed for battery longevity, it features quiescent current of 85–200 µA under active operation and ≤1 µA in disable mode, with thermal shutdown activation at ~160°C and 20°C hysteresis. Dropout behavior is defined by load-dependent V_DO, not UVLO - regulation ceases when VIN falls below VOUT + 200 mV or 2.5 V, whichever is greater.

Key Specifications

Pinout & Package

LP3988IMF-3.3 is packaged in a 5-pin SOT-23 (DBV) with body size 2.90 mm × 1.60 mm, optimized for high-density portable PCBs. Thermal performance relies on GND pin (Pin 2) connection to internal ground plane via thermal vias.

Key Features

Applications

Equivalent & Alternatives

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

Compared with LP3988IMF-3.3, TPL720F33 trades PG functionality for higher output current and slightly worse noise performance, while MCP1700T-3302E/MB sacrifices integration (no EN/PG) and package compatibility to achieve sub-2-µA shutdown, making both unsuitable as direct replacements without schematic or layout changes.

Availability

LP3988IMF-3.3 is available at Aetrix Electronics and suitable for GSM cellular handsets, CDMA baseband supplies, and portable medical sensor hubs requiring stable component supply, long-term lifecycle support, and guaranteed traceability.

Supply support for LP3988IMF-3.3 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 headquartered in Dallas, Texas, designing and manufacturing analog, embedded processing, and connectivity products for industrial, automotive, and consumer markets.

The LP3988 series was developed specifically for ultra-low-power, space-constrained battery-operated wireless devices, emphasizing micropower operation, ceramic-capacitor compatibility, and integrated power monitoring to reduce system-level component count.

FAQ

What is the maximum input voltage rating for LP3988IMF-3.3?

The absolute maximum input voltage (IN pin) for LP3988IMF-3.3 is 6.5 V. However, the recommended operating range is 2.5 V to 6 V. Exceeding 6.5 V risks permanent damage; operation above 6 V violates recommended conditions and may degrade reliability even if within absolute max limits. The device's dropout behavior begins when VIN falls below VOUT + 200 mV (i.e., 3.5 V for LP3988IMF-3.3), not at the upper limit.

Does LP3988IMF-3.3 require an external pullup resistor on the PG pin?

Yes, LP3988IMF-3.3 requires an external pullup resistor on the PG pin because it is an open-drain output. The datasheet specifies PG can be pulled up to any rail ≤6 V (e.g., VIN or VOUT) using a resistor typically between 10 kΩ and 100 kΩ. Without this pullup, the PG signal remains floating and cannot assert a valid logic-high state during normal operation, rendering the power-good monitoring function inoperative.

Can LP3988IMF-3.3 operate with zero load current?

Yes, LP3988IMF-3.3 remains stable and in regulation with no external load. This no-load stability is explicitly confirmed in the datasheet and is essential for applications like CMOS RAM keep-alive circuits or real-time clock backup supplies where the LDO must maintain regulation even when downstream circuitry is powered off. Output voltage accuracy and PSRR remain within specification under no-load conditions.

What is the thermal shutdown behavior of LP3988IMF-3.3?

LP3988IMF-3.3 activates thermal shutdown when junction temperature reaches ~160°C, disabling the output to halt power dissipation. It automatically recovers when junction temperature cools to ~140°C due to 20°C hysteresis. Continuous cycling between these thresholds indicates inadequate PCB thermal design or excessive power dissipation - sustained operation in thermal shutdown degrades long-term reliability and is not intended as a steady-state condition.

Is LP3988IMF-3.3 compatible with 1-µF ceramic output capacitors?

Yes, LP3988IMF-3.3 is specifically designed and characterized for stability with 1-µF ceramic output capacitors (X7R, Y5V, or Z5U dielectrics). The datasheet confirms stability across the 1–22 µF range with 5–500 mΩ ESR, and typical 1-µF X7R ceramics (20–40 mΩ ESR) fall well within this window. This eliminates the need for larger, more expensive tantalum capacitors and reduces board area in portable designs.