STMicroelectronics LDK120DM33R

Overview

LDK120DM33R from STMicroelectronics is a 3.3 V fixed-output, 200 mA low-dropout linear regulator with 100 mV typical dropout at 100 mA, 100 µA max quiescent current, ±2.0% output voltage tolerance at 25 °C, and operation from 1.9–5.5 V input. It delivers ultra-low noise (51 µV_RMS, 10 Hz–100 kHz with 10 nF bypass) and logic-controlled shutdown (<1 µA OFF-mode current), targeting power-sensitive portable electronics.

For engineers reviewing the LDK120DM33R datasheet, LDK120DM33R pinout, LDK120DM33R application, or LDK120DM33R equivalent, key selection criteria include dropout performance under 200 mA load, ceramic-capacitor stability (1 µF C_OUT), thermal shutdown threshold (160 °C), enable logic thresholds (0.4 V low / 1.2 V high), and SOT23-5L package compatibility with space-constrained PCB layouts.

Technical Context

The LDK120DM33R employs a PMOS pass transistor architecture enabling ultra-low dropout and near-zero ground current across load range. Its internal bandgap reference and error amplifier deliver tight DC accuracy (±2.0% at 25 °C) and low line/load regulation (0.05 %/V and 0.006 %/mA).

Noise suppression is achieved via dual-path design: a dedicated bypass pin (BYP) accepts a 10 nF capacitor to reduce output noise to 51 µV_RMS; without BYP, noise rises to 148 µV_RMS. The device integrates short-circuit current limiting (~400 mA) and thermal shutdown with 20 °C hysteresis for robust fault protection.

Key Specifications

Pinout & Package

LDK120DM33R is packaged in SOT23-5L (2.95 mm × 1.60 mm × 1.45 mm), a surface-mount 5-pin package with exposed thermal pad (not electrically connected). Pin 1 is IN, Pin 2 is GND, Pin 3 is EN, Pin 4 is BYP (bypass input for noise reduction), and Pin 5 is OUT. Pin 4 must be left floating if bypass capacitor is unused.

Key Features

Applications

Equivalent & Alternatives

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

Compared with XC6219B332MR-G and BD33IC0WEFJ-C, the LDK120DM33R uniquely combines 200 mA capability, 100 mV dropout, and 51 µV_RMS noise via bypass-making it optimal for noise-critical, battery-limited 3.3 V rails where both performance and headroom matter.

Availability

LDK120DM33R is available at Aetrix Electronics and suitable for mobile phones, digital still cameras, cordless phone base stations, and PDAs requiring stable component supply with full production status through July 2026.

Supply support for LDK120DM33R 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 silicon solutions for automotive, industrial, and consumer markets since 1987.

The LDK120 series belongs to ST's high-performance analog LDO portfolio, engineered specifically for ultra-low-noise, low-quiescent-current power delivery in space- and battery-constrained portable electronics.

FAQ

What is the minimum input voltage required for 3.3 V output at full 200 mA load?

The LDK120DM33R requires VIN ≥ VOUT + VDROP. At 200 mA and 40–125 °C, maximum dropout is 300 mV per datasheet Table 4. Thus, minimum input is 3.3 V + 0.3 V = 3.6 V. Below this, output voltage drops out of regulation.

Can the BYP pin be left unconnected without affecting basic regulation?

Yes. Pin 4 (BYP) is optional: if no 10 nF bypass capacitor is used, the pin must be left floating with no PCB trace. It is internally disconnected on the fixed-output version and does not impact DC regulation, stability, or thermal performance.

Is the SOT23-5L package RoHS-compliant and halogen-free?

Yes. Per ST's ECOPACK documentation referenced in DS9378 Rev 9 Section 7, the LDK120DM33R in SOT23-5L carries ECOPACK2 qualification - fully RoHS-compliant, halogen-free, and compliant with JEDEC J-STD-020 moisture sensitivity level 1 (MSL1).

How does thermal performance differ between SOT23-5L and DFN6 packages?

SOT23-5L has R_thJA = 160 °C/W; DFN6 (1.2 × 1.3 mm) has R_thJA = 237 °C/W. Though smaller, the DFN6's higher junction-to-ambient resistance means it runs hotter at same power dissipation. For 200 mA at 3.6 V IN → 3.3 V OUT (P_D ≈ 60 mW), SOT23-5L adds ~9.6 °C rise vs ambient; DFN6 adds ~14.2 °C.