Texas Instruments LP2954IM

Overview

LP2954IM from Texas Instruments is an adjustable-output micropower low-dropout (LDO) linear regulator in 8-pin SOIC package, delivering up to 250 mA output current with 1.23 V to 29 V programmable output, 90 µA typical quiescent current at 1 mA load, and 470 mV dropout at full load - used in battery-powered instrumentation and precision reference applications.

For engineers reviewing the LP2954IM datasheet, LP2954IM pinout, LP2954IM application, or LP2954IM equivalent, key selection considerations include its adjustable output range, ERROR flag for dropout detection, logic-controlled shutdown, reverse-battery protection on IN, and tight line/load regulation (0.04% typical) critical for stable voltage references.

Technical Context

The LP2954IM implements a precision bandgap reference (1.23 V ±1.2%) feeding an error amplifier that controls a PNP pass transistor; its integrated ERROR comparator monitors feedback voltage against reference to assert open-collector flag when output drops >5% below nominal. Shutdown input enables logic-level disable with <1.2 V threshold and 105 µA ground current in shutdown mode.

It supports external resistor programming of output voltage via FEEDBACK and SENSE pins, with bias current (20–40 nA) and thermal coefficient (20 ppm/°C) directly impacting accuracy; stability requires ≥2.2 µF output capacitance (≥6.8 µF for 1.23 V outputs), and reverse-battery protection applies only to the IN pin - not SHUTDOWN unless externally pulled up.

Key Specifications

Pinout & Package

LP2954IM is housed in an 8-pin SOIC (D package), 4.90 mm × 3.91 mm body size, with exposed pad not electrically connected. Pin functions are validated per TI SNVS096E Rev E (July 2016) datasheet Section 5.

Key Features

Applications

Equivalent & Alternatives

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

Compared with LP2954IM, LP2951CMX/NOPB offers identical adjustability and package but omits the ERROR function - reducing diagnostic capability - while TLV70733PDQNR trades adjustability and control features for significantly lower quiescent current and smaller size in fixed-voltage roles.

Availability

LP2954IM is available at Aetrix Electronics and suitable for battery-powered instrumentation, industrial sensor transmitters, programmable lab supplies, and medical point-of-care devices requiring stable component supply with long lifecycle support.

Supply support for LP2954IM 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 ICs, embedded processors, and high-performance analog components for industrial, automotive, and consumer markets.

The LP2954IM belongs to TI's legacy micropower LDO family, engineered specifically for battery longevity and precision voltage regulation in portable and harsh-environment applications where low dropout, low IQ, and fault awareness are critical.

FAQ

What output voltage range does the LP2954IM support, and how is it set?

The LP2954IM supports an output voltage range of 1.23 V to 29 V, set using an external resistor divider connected between OUT, SENSE, and FEEDBACK pins. The formula is VOUT = VREF × (1 + R1/R2), where VREF = 1.23 V. For example, R1 = 97.6 kΩ and R2 = 10 kΩ yields 12 V output. LP2954IM requires no internal trimming - accuracy depends on resistor tolerance and VREF specification.

Does the LP2954IM include reverse-battery protection, and on which pins?

Yes, the LP2954IM includes reverse-battery protection on the IN pin only, achieved via an internal diode to GND that blocks −20 V (absolute max). This protection does not extend to the SHUTDOWN pin - tying SHUTDOWN directly to IN sacrifices reverse protection unless a pullup resistor (20–100 kΩ to VIN) is used. The LP2954IM datasheet explicitly confirms this limitation in Section 7.4.1.

What is the purpose of the ERROR pin on the LP2954IM, and how should it be interfaced?

The ERROR pin on the LP2954IM is an open-collector output that asserts LOW when the regulated output drops >5% below nominal (e.g., <4.75 V for a 5 V setting), indicating dropout, thermal limit, or current limit. It requires an external pullup resistor (100 kΩ–1 MΩ) - TI recommends connecting to VOUT to avoid invalid HIGH states during low-VIN conditions. The LP2954IM ERROR pin sinks up to 400 µA and is fully specified in Section 6.5 of the datasheet.

Can the LP2954IM be used without an external capacitor on the output pin?

No - the LP2954IM requires a minimum 2.2 µF capacitor from OUT to GND for stability, as confirmed in Section 8.2.2.1 of the datasheet. Omitting it risks oscillation. For outputs ≤3.3 V, ≥4.7 µF is required; for 1.23 V at 250 mA, ≥6.8 µF is mandatory. Capacitor ESR must be ≤5 Ω, and ceramic/tantalum types are acceptable - but aluminum electrolytics may freeze below −25°C.

How does the LP2954IM's quiescent current behave under load and at dropout?

The LP2954IM's quiescent current remains extremely low: 90 µA typical at 1 mA load, rising only to 120 µA at dropout (VIN = VOUT + VDO), and reaching 21 µA at 250 mA load. This near-constant IQ across load ensures predictable battery drain - unlike many LDOs whose IQ surges near dropout. All values are measured per TI SNVS096E Rev E, Table 6.5, and directly enable multi-year operation in always-on sensor nodes using LP2954IM.