STMicroelectronics LDK320ADU33R

Overview

LDK320ADU33R from STMicroelectronics is a 3.3 V fixed-output, high-accuracy (±0.5% at 25 °C), low-dropout linear regulator delivering up to 200 mA with 100 mV typical dropout at 100 mA load, 88 dB PSRR at 120 Hz, and 63 μV_RMS output noise (10 Hz–100 kHz). It operates from 2.5 V to 18 V input and features logic-controlled shutdown (<1 μA off-mode current), thermal/short-circuit/SOA protection, and ceramic capacitor compatibility (C_OUT = 1 μF).

For engineers reviewing the LDK320ADU33R datasheet, LDK320ADU33R pinout, LDK320ADU33R application, or LDK320ADU33R equivalent, this device is selected for battery-powered DSC, BD/DVD, and industrial control subsystems where tight voltage tolerance, low quiescent current, and stable regulation under dynamic load are critical.

Technical Context

The LDK320ADU33R employs a bandgap-referenced op-amp control loop with internal bias generator and thermal shutdown circuitry (trip point 160 °C, 20 °C hysteresis). Its architecture supports both fixed-output (3.3 V) and adjustable versions, though the ADU33R variant uses the SOT23-5L package with dedicated EN and OUT pins and no ADJ functionality.

It integrates current limiting (330 mA short-circuit current), SOA protection, and is stabilized with ≥1 μF ceramic output capacitance. The enable input accepts logic-level signals (V_ENL ≤ 0.4 V, V_ENH ≥ 1.2 V) across –40 °C to 125 °C, enabling precise power sequencing in multi-rail systems.

Key Specifications

Pinout & Package

SOT23-5L (5-pin small outline transistor) package with exposed pad for thermal enhancement; footprint compatible with standard SOT-23 land patterns and reflow assembly.

Key Features

Applications

Equivalent & Alternatives

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

Compared with XC6206P332MR and AP2204K-3.3TRG1, the LDK320ADU33R delivers superior accuracy (±0.5% vs. ±2%), lower dropout (100 mV vs. ≥150 mV), and higher PSRR (88 dB vs. ≤45 dB), making it optimal for precision, low-power, and noise-critical designs despite its higher unit cost.

Availability

LDK320ADU33R is available at Aetrix Electronics and suitable for digital still camera (DSC), Blu-ray disc player, and industrial programmable logic controller (PLC) applications requiring stable component supply, long-term lifecycle support, and traceable sourcing.

Supply support for LDK320ADU33R 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 devices for automotive, industrial, and consumer markets.

The LDK320 series belongs to ST's high-accuracy, low-noise LDO portfolio, engineered specifically for battery-powered and noise-sensitive applications demanding tight regulation, ultra-low quiescent current, and robust fault protection.

FAQ

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

The LDK320ADU33R requires VIN ≥ VOUT + VDROP to maintain regulation. At 200 mA and 125 °C, max dropout is 350 mV (Table 6), so minimum input is 3.3 V + 0.35 V = 3.65 V. At 25 °C, typical dropout is 200 mV, allowing 3.5 V input. Operation below 3.65 V at full load and high temperature risks dropout and output collapse.

Can the LDK320ADU33R be used with tantalum or aluminum electrolytic capacitors instead of ceramic?

No - the LDK320ADU33R is optimized for ceramic output capacitors (1–22 μF, ESR <1 Ω). Tantalum or aluminum electrolytics typically exhibit higher ESR (>100 mΩ to several Ω) and can cause instability or oscillation. ST's stability plots (Figures 25–26) explicitly define the ceramic C_OUT/ESR boundary; using non-ceramic types voids guaranteed performance.

Is the SOT23-5L package thermally adequate for 200 mA continuous output at 125 °C ambient?

With R_thJA = 160 °C/W (Table 5), power dissipation at 200 mA and 3.3 V output with 5 V input is P_D = (5 − 3.3) × 0.2 = 0.34 W, yielding ΔT = 0.34 × 160 = 54.4 °C rise. At 125 °C ambient, junction temperature reaches ~179 °C - exceeding the 125 °C rating. Derating or PCB copper pour (reducing R_thJA) is mandatory for full-load operation at high ambient.

Does the LDK320ADU33R support reverse-voltage or reverse-current protection?

No - the LDK320ADU33R lacks integrated reverse-voltage or reverse-current blocking. If input polarity reversal or back-driving from the output is possible (e.g., hot-swap scenarios), an external series Schottky diode or ideal diode controller must be added. The device only protects against overcurrent, overtemperature, and SOA violations - not reverse faults.