onsemi LM2931CD2TG

Overview

LM2931CD2TG from onsemi is an adjustable-output low-dropout (LDO) voltage regulator with load dump protection, 60 V transient tolerance, and output inhibit functionality. It delivers ≥100 mA output current with dropout voltage as low as 0.16 V at 100 mA and bias current of 0.4 mA at 10 mA - enabling extended battery life in automotive and portable industrial systems.

For engineers reviewing the LM2931CD2TG datasheet, pinout, applications, or equivalent options, key selection criteria include its adjustable output range (3.0–24 V), −50 V reverse polarity protection, thermal shutdown, internal current limiting, and D2PAK-5 package compatibility with high-power dissipation requirements.

Technical Context

The LM2931CD2TG implements a PNP pass transistor architecture with integrated reference, error amplifier, and protection circuitry including overvoltage shutdown (26–40 V threshold), reverse polarity clamp, and mirror-image insertion tolerance. Its adjustable output is set via external resistive divider connected to the ADJ pin.

It requires an external output capacitor for stability (minimum 10 µF, ESR ≤ 0.4 Ω), supports output inhibit control (2.15–3.25 V turn-on threshold), and operates across −40 °C to +125 °C ambient temperature - meeting AEC-Q100 stress test requirements when used in NCV variants.

Key Specifications

Pinout & Package

D2PAK-5 (Case 936A) package with exposed thermal pad; vertical mounting recommended for optimal thermal performance (R_JA = 70 °C/W, R_JC = 5.0 °C/W).

Key Features

Applications

Equivalent & Alternatives

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

Compared with LM2931ACD2TR4G and NCV2931ACD2TR4G, the LM2931CD2TG offers the same robust protection and thermal performance at lower cost and broader commercial availability - making it optimal for non-automotive industrial and portable applications where ±5% output tolerance is acceptable.

Availability

LM2931CD2TG is available at Aetrix Electronics and suitable for automotive body electronics, industrial handheld instruments, portable medical devices, and telematics systems requiring stable component supply with long lifecycle support.

Supply support for LM2931CD2TG 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

onsemi (formerly ON Semiconductor) is a global semiconductor supplier focused on energy-efficient electronics, with leadership in automotive, industrial, cloud, and IoT markets.

The LM2931 series was designed specifically for harsh-environment power regulation - combining automotive-grade ruggedness (load dump, reverse polarity, thermal survival) with low-quiescent LDO efficiency for battery longevity.

FAQ

What is the maximum input voltage the LM2931CD2TG can withstand during load dump events?

The LM2931CD2TG is rated for 60 V transient input voltage (≤100 ms duration), complying with ISO 7637-2 Pulse 5a requirements for 12 V automotive systems. This allows direct connection to vehicle battery rails without external TVS diodes in most cases. The device also tolerates −50 V reverse polarity transients. These ratings are validated per onsemi's datasheet maximum ratings table and apply across the full −40 °C to +125 °C operating temperature range. LM2931CD2TG integrates all protection circuitry internally.

Does the LM2931CD2TG require an external output capacitor, and what are the stability requirements?

Yes, the LM2931CD2TG is not internally compensated and requires an external output capacitor for stability. Minimum recommended value is 10 µF, with impedance |Z_O| ≤ 0.4 Ω across operating temperature (−40 °C to +125 °C). Electrolytic capacitors must be rated for −40 °C minimum; solid tantalum is preferred for compact designs. Stability is verified using Figure 22 and Figure 23 from the LM2931 datasheet. LM2931CD2TG's stability boundary depends on load current and output voltage - worst case occurs at max load and min V_OUT.

What is the function of Pin 2 (Output Inhibit) on the LM2931CD2TG, and what voltage thresholds activate it?

Pin 2 is the Output Inhibit terminal: applying voltage <1.20 V (max, −40 °C to +125 °C) disables the output; applying >2.15 V (typ) at 25 °C enables regulation. Turn-on threshold decreases to 1.90 V (min) at 25 °C and increases to 3.25 V (max) at cold temperatures. This logic-compatible control allows microprocessor-driven power sequencing and ultra-low standby current. LM2931CD2TG draws only 0.2 µA in inhibited state, preserving battery charge during sleep modes.

Can the LM2931CD2TG be used to generate a fixed 3.3 V output, and how is the feedback network calculated?

Yes, LM2931CD2TG supports fixed 3.3 V output using an external resistor divider from OUT to ADJ to GND. With V_REF = 1.20 V, select R2 = 10 kΩ and R1 = 17.5 kΩ (standard 1% values) to achieve V_OUT = 1.20 × (1 + 17.5k/10k) = 3.30 V. Adjustment pin current (≤0.2 µA) introduces negligible error. LM2931CD2TG's ±5% reference tolerance results in ±5% output variation unless trimmed; for tighter accuracy, use LM2931ACD2TR4G (±2.5%).

What thermal performance can be expected from the LM2931CD2TG in a D2PAK-5 package on a standard PCB?

In vertical mounting configuration, LM2931CD2TG has R_JA = 70 °C/W and R_JC = 5.0 °C/W. With 100 mA load and 1 V dropout (100 mW dissipation), junction-to-ambient rise is ~7 °C - well within safe margin below +150 °C max. For continuous 100 mA at high ambient (e.g., +85 °C), board copper area must be optimized per Figure 26: ≥70 mm length of 2 oz. copper per side reduces R_JA to ~40 °C/W. LM2931CD2TG's exposed thermal pad must be soldered to inner-layer copper planes for effective heat transfer.