STMicroelectronics LDK120M33R

Overview

LDK120M33R from STMicroelectronics is a 200 mA, 3.3 V fixed-output low-dropout linear regulator with 100 mV typical dropout at 100 mA, 100 µA max quiescent current, and 51 µV_RMS output noise (10 Hz–100 kHz) when using a 10 nF bypass capacitor. It operates from 1.9 V to 5.5 V input, supports logic-controlled shutdown (<1 µA OFF mode), and is stabilized with a 1 µF ceramic output capacitor. It targets power-sensitive portable electronics requiring stable, ultra-low-noise bias.

For engineers reviewing the LDK120M33R datasheet, LDK120M33R pinout, LDK120M33R application, or LDK120M33R equivalent, key selection criteria include dropout voltage under load, noise performance with/without bypass, enable threshold stability over temperature, thermal shutdown hysteresis, and compatibility with 1 µF ceramic output capacitance across -40 °C to 125 °C.

Technical Context

The LDK120M33R employs a PMOS pass transistor architecture enabling ultra-low dropout and near-zero gate-drive current, resulting in sub-100 µA quiescent operation even at full 200 mA load. Its internal bandgap reference and error amplifier deliver ±2.0% output accuracy at 25 °C and ±3.0% over full temperature range.

Noise suppression is achieved via dual-path design: the fixed version integrates an optional bypass pin (BYP) for external 10 nF capacitor to reduce output noise to 51 µV_RMS; without it, noise rises to 148 µV_RMS. Supply voltage rejection remains 55 dB from 120 Hz to 10 kHz independent of bypass configuration.

Key Specifications

Pinout & Package

LDK120M33R is packaged in SOT23-5L (2.95 mm × 1.60 mm × 1.45 mm), a space-constrained surface-mount package suitable for high-density portable PCBs. Thermal resistance is 160 °C/W junction-to-ambient, requiring minimal copper pour for 200 mA continuous operation.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar low-noise LDO applications.

Compared with XC6210B332MR-G, LDK120M33R trades 13 µV_RMS noise for 50 mA extra current and integrated enable; versus BD33IC0WEFJ-C, it delivers 60 µA lower quiescent current and flexible noise optimization via BYP pin - making it superior for battery-constrained, thermally dense, and sequenced-power designs.

Availability

LDK120M33R is available at Aetrix Electronics and suitable for mobile phones, digital still cameras, cordless phones, and personal digital assistants requiring stable component supply with guaranteed long-term manufacturability through July 2026.

Supply support for LDK120M33R 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, Switzerland, designing and manufacturing microcontrollers, power management ICs, sensors, and analog chips for automotive, industrial, and consumer markets.

The LDK120 series was developed specifically for ultra-low-power, low-noise portable electronics, emphasizing minimal quiescent current, ceramic-capacitor stability, and robust thermal behavior in miniature packages like SOT23-5L and DFN6.

FAQ

What is the minimum input voltage required for LDK120M33R to maintain regulation at 200 mA load?

The minimum input voltage is calculated as V_OUT + V_DROP = 3.3 V + 300 mV = 3.6 V, based on the maximum dropout voltage of 300 mV at 200 mA and 125 °C. At room temperature, dropout drops to 150 mV, allowing regulation down to 3.45 V. Input below 3.6 V at high temperature causes output collapse.

Can LDK120M33R operate without the BYP capacitor, and how does that affect noise performance?

Yes, the BYP pin may be left unconnected (floating) with no routing. In this configuration, output noise increases from 51 µV_RMS to 148 µV_RMS (10 Hz–100 kHz), as confirmed in Table 4 footnote 2. This is acceptable for digital I/O rails but insufficient for precision analog circuits like ADC references or RF synthesizers.

Is LDK120M33R compatible with 1 µF X7R ceramic capacitors from major vendors like Murata or TDK?

Yes - the datasheet explicitly states compatibility with 1 µF ceramic output capacitors, and Figure 25 confirms stable operation with C_OUT = 1 µF and ESR as low as 0.01 Ω. X7R dielectrics from Murata (GRM series) and TDK (C series) meet these requirements and are widely used in production designs.

Does LDK120M33R require an input capacitor, and what value is recommended?

Yes, a 1 µF ceramic input capacitor (C_IN) is required per Figure 3 and Section 3. It must be placed within 2 mm of the IN and GND pins to suppress high-frequency noise from upstream sources and ensure transient response stability. X5R or X7R 0402/0603 case sizes are standard.