STMicroelectronics LDK220C33R

Overview

LDK220C33R from STMicroelectronics is a fixed-output 3.3 V, 200 mA low-dropout linear regulator in SOT23-5L package, featuring 100 mV typical dropout at 100 mA, ±2.0% output voltage tolerance at 25 °C, and logic-controlled enable with <1 µA shutdown current. It delivers stable power to noise-sensitive circuits in space-constrained battery-powered systems.

For engineers reviewing the LDK220C33R datasheet, LDK220C33R pinout, LDK220C33R application, or LDK220C33R equivalent, key selection criteria include dropout performance at 200 mA load, ceramic capacitor compatibility (1 µF min), thermal shutdown threshold (160 °C), EN pin logic thresholds (0.4 V low / 1.2 V high), and quiescent current behavior across -40 °C to 125 °C.

Technical Context

The LDK220C33R implements a bandgap-referenced op-amp control loop with internal current limiting and thermal protection. Its architecture supports fast transient response-load step recovery within ~20 µs-and integrates an active output discharge function triggered when EN is low (R_dis = 18 Ω).

It operates across 2.5 V to 13.2 V input range while maintaining regulation down to 100 mV headroom at 100 mA. The device embeds bias generator, thermal shutdown hysteresis (20 °C), and short-circuit constant-current limiting (400 mA typ.), with SVR of 55 dB at 120 Hz–1 kHz and 50 dB at 10 kHz.

Key Specifications

Pinout & Package

LDK220C33R is packaged in SOT23-5L (ECOPACK® compliant), measuring 2.95 mm × 1.60 mm × 1.45 mm (max height), with exposed pad for thermal enhancement. Pin 1 is IN; pin 2 is GND; pin 3 is EN; pin 4 is NC (not connected, fixed version); pin 5 is OUT.

Key Features

Applications

Equivalent & Alternatives

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

Compared with XC6219B332MR-G and AP7361-33SG-13, the LDK220C33R uniquely balances ultra-low dropout (100 mV), sub-1 µA shutdown, integrated discharge, and 20 µV_RMS noise - making it optimal for battery-constrained, noise-sensitive, and sequenced-power applications where all four attributes are simultaneously required.

Availability

LDK220C33R is available at Aetrix Electronics and suitable for industrial sensor nodes, USB-C PD monitors, HDMI audio processors, and medical wearable ECG front-ends requiring stable component supply, long-lifecycle support, and ECOPACK-compliant packaging.

Supply support for LDK220C33R 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 LDK220 series belongs to ST's high-performance analog LDO portfolio, engineered specifically for ultra-low-power, low-noise, and thermally robust operation in space- and energy-constrained embedded systems.

FAQ

What is the minimum input voltage required for regulation at 3.3 V output?

The LDK220C33R maintains regulation down to VIN = VOUT + VDROP. With 100 mV typical dropout at 100 mA, minimum input is 3.4 V under that condition; at 200 mA and 125 °C, dropout rises to 350 mV, requiring VIN ≥ 3.65 V. Absolute minimum VIN is 2.5 V per datasheet, but regulation is not guaranteed below VOUT + VDROP.

Can the LDK220C33R be used with a 10 µF X7R ceramic capacitor on the output?

Yes - the device is stable with output capacitances from 1 µF to 22 µF, including X7R ceramics. A 10 µF X7R capacitor improves load transient response and reduces output impedance across 10 Hz–100 kHz, while remaining within the stability region defined in Figure 22 of DS10219.

Is the EN pin internally pulled up or does it require an external resistor?

The EN pin has no internal pull-up; it must be actively driven high (≥1.2 V) to enable regulation or pulled low (≤0.4 V) to enter shutdown. Leaving EN floating violates absolute maximum ratings and may cause erratic operation - a 100 kΩ pull-up to VIN is recommended if MCU control is unavailable.

Does the output discharge function activate automatically when EN is low, and what is its resistance?

Yes - the internal discharge path activates immediately upon EN going low, connecting VOUT to GND through a nominal 18 Ω resistor. This discharges COUT rapidly (τ ≈ 18 Ω × 1 µF = 18 µs), preventing residual voltage from interfering with downstream logic reset timing or causing latch-up in powered-off subsystems.