Texas Instruments LM2937ET-10

Overview

LM2937ET-10 from Texas Instruments is a 10-V, 500-mA positive low-dropout linear regulator using a PNP pass transistor, featuring 0.5-V typical dropout at full load, ±5% output voltage tolerance over temperature and load, and integrated reverse-battery, thermal shutdown, and short-circuit protection. It is designed for automotive power rails where input transients up to 60 V and ambient operation from −40°C to 125°C are required.

For engineers reviewing the LM2937ET-10 datasheet, LM2937ET-10 pinout, LM2937ET-10 application, or LM2937ET-10 equivalent, key selection considerations include dropout voltage under 500-mA load, stability with 10-μF/≤3-Ω-ESR output capacitors, reverse-input protection down to −50 V, transient immunity up to 60 V, and TO-220 thermal performance without external heatsink in moderate-power automotive modules.

Technical Context

The LM2937ET-10 employs a PNP-based LDO architecture with internal bandgap reference and current-limiting circuitry, enabling regulation with only 0.5 V (typ) headroom at 500 mA. Its compensation network supports stable operation across a wide ESR range (10 mΩ to 3 Ω), eliminating strict capacitor type constraints.

Protection features include overvoltage shutdown triggered at ~32 V input, thermal shutdown at 150°C junction temperature, and foldback current limiting that transitions into thermal shutdown under sustained overload. No enable or UVLO function is present - regulation begins when VIN exceeds VOUT + 1 V.

Key Specifications

Pinout & Package

LM2937ET-10 uses the TO-220 (NDE) package: 14.986 mm × 10.66 mm body, 3-pin vertical mount, with metal tab internally connected to GND for thermal conduction. Mounting the tab to a large copper pour improves thermal resistance from 77.9°C/W (free-air) to ≤40°C/W.

Key Features

Applications

Equivalent & Alternatives

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

Compared with LM2940CT-10 and MCP1703T-1002E/MB, the LM2937ET-10 uniquely combines 500-mA capability, 0.5-V dropout, −50-V reverse immunity, and 60-V transient tolerance in a thermally robust TO-220 package - making it the only drop-in solution for primary 10-V automotive power rails requiring full ISO 7637-2 compliance.

Availability

LM2937ET-10 is available at Aetrix Electronics and suitable for automotive body control, industrial PLC I/O, point-of-load sensor biasing, and aftermarket telematics requiring stable component supply across extended temperature and high-reliability environments.

Supply support for LM2937ET-10 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, delivering analog and embedded processing solutions for industrial, automotive, and personal electronics markets.

The LM2937 product line was engineered specifically for automotive power management - emphasizing ruggedness against reverse battery, load dump, and extreme temperature cycling while maintaining tight regulation and low quiescent current.

FAQ

What is the minimum input voltage required for LM2937ET-10 to maintain regulation at full 500-mA load?

The LM2937ET-10 requires a minimum input-to-output differential of 0.5 V (typical) to remain in regulation. Therefore, with a nominal 10-V output, the minimum input voltage is 10.5 V at 500 mA. The datasheet guarantees ≤1 V dropout across −40°C to 125°C, so 11 V input ensures regulation under worst-case conditions. This makes LM2937ET-10 suitable for automotive cold-crank scenarios where battery voltage dips to 6–8 V - provided upstream boost or hold-up capacitance raises the input above 11 V.

Can LM2937ET-10 operate without an output capacitor?

No, LM2937ET-10 requires a minimum 10-μF output capacitor with ESR between 10 mΩ and 3 Ω for loop stability. Omitting the capacitor or using one outside this ESR range risks oscillation, output ripple amplification, or thermal runaway. The capacitor must be placed adjacent to the OUTPUT and GND pins. Ceramic, aluminum electrolytic, or polymer types meeting the ESR specification are acceptable - the LM2937ET-10's internal compensation relaxes ESR constraints compared to standard LDOs.

Does LM2937ET-10 include an enable pin or shutdown function?

No, LM2937ET-10 has no enable (EN) pin or active-low shutdown feature. It operates continuously whenever input voltage exceeds VOUT + 1 V. Regulation begins gradually as VIN rises above this threshold, and the device draws quiescent current (2–10 mA) across its full input range. For applications requiring controlled startup or low-quiescent sleep mode, an external MOSFET switch or dedicated enable-capable LDO like TPS7B6950-Q1 must be used upstream of LM2937ET-10.

What thermal derating applies to LM2937ET-10 in a TO-220 package without a heatsink?

In free-air (no heatsink), the LM2937ET-10 TO-220 package has RθJA = 77.9°C/W. At 25°C ambient and 500-mA load with 12-V input, power dissipation is (12 − 10) × 0.5 = 1 W, causing ~78°C junction rise - resulting in ~103°C junction temperature, well below the 125°C max. However, at 85°C ambient and 26-V input, PD = (26 − 10) × 0.5 = 8 W → junction would exceed 150°C. Thus, heatsinking is mandatory for high VIN/high ambient operation - LM2937ET-10's thermal shutdown activates at 150°C to prevent damage.

Is LM2937ET-10 compatible with ceramic output capacitors?

Yes, LM2937ET-10 is compatible with ceramic output capacitors, provided their ESR is ≥10 mΩ. Standard X7R/X5R ceramics often have ESR < 5 mΩ, which falls below the minimum stable range and may cause oscillation. To ensure stability, either use ceramic capacitors with built-in ESR (e.g., specialty "anti-resonant" types), add a small series resistor (e.g., 10–100 mΩ), or parallel the ceramic with a higher-ESR capacitor such as aluminum polymer. The LM2937ET-10 datasheet explicitly validates stability with ESR as low as 10 mΩ - unlike many older LDOs that require ≥100 mΩ.