STMicroelectronics LDL112D33R

Overview

LDL112D33R from STMicroelectronics is a 3.3 V fixed-output, 1.2 A low-dropout linear regulator with PMOS pass transistor architecture, ±2.0% output voltage accuracy at 25 °C, 300 mV typical dropout at 1 A, and reverse current protection. It operates from 1.6–5.5 V input and supports ceramic output capacitors as low as 1 µF - deployed in USB-powered portable devices requiring stable low-noise 3.3 V rail generation.

For engineers reviewing the LDL112D33R datasheet, LDL112D33R pinout, LDL112D33R application, or LDL112D33R equivalent, key selection criteria include dropout voltage under full load, shutdown current (<1 µA), thermal resistance (100 °C/W in PPAK), reverse current blocking behavior, and compatibility with 1 µF ceramic COUT.

Technical Context

The LDL112D33R uses a PMOS-based LDO topology with internal bandgap reference (800 mV) and error amplifier driving the gate of the pass transistor. Its enable logic interface (EN pin) controls high-side MOSFET conduction, enabling sub-1 µA off-state current via gate-bulk switching to VOUT during reverse bias conditions.

Reverse current protection is implemented through dynamic gate and bulk node control: when VOUT exceeds VIN by >100 mV - whether EN is high or low - the MOSFET channel is fully blocked by zero VGS and isolation of all parasitic paths, preventing backfeed into the input supply.

Key Specifications

Pinout & Package

LDL112D33R is available in SO8-batwing and PPAK packages. The SO8-batwing variant uses standard 8-pin gull-wing leadframe; PPAK offers enhanced thermal performance (R_thJC = 8 °C/W) with exposed thermal pad tied to GND.

Key Features

Applications

Equivalent & Alternatives

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

Compared with TSM1033S and AP2210K-3.3TRG1, LDL112D33R uniquely combines reverse current protection, sub-1 µA shutdown, and 300 mV dropout in a single 3.3 V device - making it optimal for battery-fed systems where input source isolation and ultra-low standby power are mandatory.

Availability

LDL112D33R is available at Aetrix Electronics and suitable for USB-powered devices, portable medical monitors, and low-voltage point-of-load applications requiring stable component supply across automotive, industrial, and consumer product lifecycles.

Supply support for LDL112D33R 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

STMicroelectronics is a global semiconductor leader headquartered in Geneva, specializing in power management, microcontrollers, and analog ICs for industrial, automotive, and consumer markets.

The LDL112 series was designed specifically for ultra-low-power, reverse-current-protected LDO applications in space-constrained battery-operated systems - emphasizing quiescent current optimization, ceramic capacitor compatibility, and robust fault handling.

FAQ

What is the minimum input voltage required for LDL112D33R to maintain regulation at 1.2 A load?

The minimum input voltage is determined by dropout: at 1.2 A, max dropout is 600 mV (−40 °C to 125 °C). For 3.3 V output, VIN must be ≥3.9 V to sustain full load. At room temperature, 3.6 V input suffices due to 300–350 mV typical dropout.

Can LDL112D33R be used with a 10 µF aluminum electrolytic output capacitor?

No - the LDL112D33R is optimized for ceramic capacitors (1–10 µF, ESR < 100 mΩ). Aluminum electrolytics typically exceed 100 mΩ ESR and lack the high-frequency impedance profile needed for stability; using them risks oscillation or poor transient response.

Does LDL112D33R provide output discharge when disabled?

No - output discharge is an optional feature available only on specific variants (e.g., LDL112PVR with "D" suffix indicating discharge option). The LDL112D33R part number denotes fixed 3.3 V output without integrated discharge FET; external circuitry is required if rapid VOUT decay is needed.

How does reverse current protection behave when EN = GND and VOUT = 4.0 V while VIN = 0 V?

With EN = GND, the internal MOSFET is fully off and gate/bulk nodes are switched to VOUT. This blocks all conduction paths from VOUT to VIN, limiting reverse current to <10 nA - confirmed by datasheet Section 6.3 Case 1, even with VOUT > VIN + 100 mV.