STMicroelectronics LDK120C33R

Overview

LDK120C33R 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, 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 RF or analog circuitry.

For engineers reviewing the LDK120C33R datasheet, LDK120C33R pinout, LDK120C33R application, or LDK120C33R equivalent, this page delivers verified electrical behavior, package-specific terminal mapping, real-world use cases in battery-powered systems, and validated alternative options - all grounded in ST's DS9378 Rev 9 production data.

Technical Context

The LDK120C33R employs a PMOS pass transistor architecture enabling ultra-low dropout voltage and near-zero gate-drive current, eliminating external compensation requirements. Its internal bandgap reference and error amplifier deliver ±2.0% output accuracy at 25 °C and ±3.0% over –40 °C to 125 °C.

It integrates thermal shutdown (160 °C trip, 20 °C hysteresis), short-circuit constant-current limiting (~400 mA), and logic-compatible enable input (V_IL ≤ 0.4 V, V_IH ≥ 1.2 V). The BYP pin on SOT23-5L/SOT323-5L packages enables optional noise reduction via external 10 nF capacitor - a feature absent in DFN6 variants where that pin is NC.

Key Specifications

Pinout & Package

LDK120C33R is available in SOT323-5L package (1.8 × 2.0 mm footprint, 0.95 mm height), optimized for space-constrained portable designs. Pin functions are identical across SOT23-5L and SOT323-5L variants per Table 1 of DS9378 Rev 9.

Key Features

Applications

Equivalent & Alternatives

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

Compared with XC6210B332MR-G and ADP160AUJZ-3.3-R7, the LDK120C33R uniquely balances 200 mA capability, 100 mV dropout, and 51 µV_RMS noise via BYP - making it the only choice among the three for noise-critical 3.3 V rails fed from single Li-ion cells.

Availability

LDK120C33R is available at Aetrix Electronics and suitable for mobile phones, digital still cameras, Bluetooth audio modules, and industrial handheld terminals requiring stable component supply with guaranteed long-term manufacturability through July 2026.

Supply support for LDK120C33R 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 was developed specifically for ultra-low-power, low-noise portable electronics - emphasizing minimal quiescent current, ceramic-capacitor compatibility, and robust thermal performance in miniature packages.

FAQ

What is the minimum input voltage required for LDK120C33R to maintain regulation at full 200 mA load?

The minimum input voltage is calculated as V_OUT + V_DROP. At 200 mA and 125 °C, the maximum dropout is 300 mV (per Table 4). Thus, VIN(min) = 3.3 V + 0.3 V = 3.6 V. Below this, output voltage drops linearly with input - confirmed by Figure 34 and 35 in DS9378 Rev 9.

Can the BYP pin be left unconnected without affecting stability or regulation?

Yes. Per Table 1 and Section 3 of DS9378 Rev 9, the BYP pin is optional for noise reduction. If unused, it must be left floating with no PCB trace - not tied to GND or OUT. Stability remains guaranteed with only 1 µF C_OUT; the BYP cap improves noise only and does not impact loop compensation.

Does LDK120C33R require an input capacitor, and what value is recommended?

Yes. A 1 µF X5R or X7R ceramic capacitor (C_IN) is required on the IN pin, placed as close as possible to the device. This minimizes high-frequency impedance and prevents oscillation under transient load conditions - specified in Section 3 "Typical application" and Figure 3 of DS9378 Rev 9.

Is the SOT323-5L package RoHS-compliant and lead-free?

Yes. Per Section 7 "Package mechanical data" in DS9378 Rev 9, LDK120C33R is offered in ECOPACK®-compliant packages. The SOT323-5L variant carries the "ECOPACK2" designation, meaning it is lead-free, halogen-free, and compliant with EU RoHS Directive 2011/65/EU and REACH Regulation EC 1907/2006.