STMicroelectronics LDK320M-R

Overview

LDK320M-R from STMicroelectronics is a 200 mA low-dropout linear regulator with fixed 3.3 V output, ±2% accuracy at 25 °C, 100 mV typical dropout at 100 mA, and 88 dB PSRR at 120 Hz. It operates from 2.5 V to 18 V input and features logic-controlled shutdown (EN pin), thermal/short-circuit protection, and stable operation with 1 μF ceramic output capacitor. It is used in power rails for digital signal processors and consumer optical drives.

For engineers reviewing the LDK320M-R datasheet, LDK320M-R pinout, LDK320M-R application, or LDK320M-R equivalent, key selection criteria include dropout voltage under load, quiescent current in active and shutdown modes, PSRR performance across frequency, output voltage tolerance over temperature, and compatibility with low-ESR ceramic capacitors in SOT23-5L packaging.

Technical Context

The LDK320M-R implements a bandgap-referenced op-amp control loop with internal bias generator and thermal shutdown circuitry. Its EN pin directly controls the pass transistor gate via logic-level input (V_ENH = 1.2 V min), enabling sub-1 μA off-state current. The architecture supports fast transient response due to low output impedance and optimized compensation for 1 μF C_OUT.

It integrates SOA protection limiting output current to 330 mA (typ.) and thermal shutdown at 160 °C with 20 °C hysteresis. Dropout behavior is characterized up to 350 mV at 200 mA and 125 °C, and line/load regulation is specified separately for SOT23-5L and SOT-89 packages to reflect package-dependent thermal resistance.

Key Specifications

Pinout & Package

LDK320M-R is available in SOT23-5L package (5-pin surface-mount, 1.25 mm max height). Pinout is validated per DS11321 Rev 13, Table 1: Pin 1 = IN, Pin 2 = GND, Pin 3 = EN, Pin 4 = NC (not connected, fixed version), Pin 5 = OUT.

Key Features

Applications

Equivalent & Alternatives

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

Compared with LDK320AM-R, the LDK320M-R trades accuracy for cost and availability; compared with LDK220M-R, it delivers higher current headroom and superior PSRR-making it optimal for mixed-signal SoC power domains requiring both robustness and noise immunity.

Availability

LDK320M-R is available at Aetrix Electronics and suitable for digital signal processing, optical disc drive servo control, and industrial programmable logic controller I/O modules requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for LDK320M-R 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 analog, power, microcontroller, and sensor solutions for industrial, automotive, and consumer markets.

The LDK320 series belongs to ST's high-PSRR, low-I_Q LDO portfolio, engineered specifically for battery-powered and noise-sensitive embedded systems requiring ultra-stable voltage rails with minimal board space.

FAQ

What is the minimum input voltage required for LDK320M-R to maintain 3.3 V output at 200 mA?

The minimum input voltage equals the nominal output plus dropout voltage. At 200 mA and 125 °C, dropout is up to 350 mV per Table 6, so VIN(min) = 3.3 V + 0.35 V = 3.65 V. At 25 °C, typical dropout is 200 mV, yielding VIN(min) = 3.5 V. Input must remain ≥2.5 V absolute minimum per absolute ratings, but regulation fails below the dropout threshold.

Can LDK320M-R be used with a 10 μF ceramic output capacitor?

Yes. The device is stable with ceramic capacitors from 1 μF to 22 μF, as confirmed in Tables 6 and 7 and Figure 25. A 10 μF X7R ceramic capacitor with ESR ≤1 Ω meets the stability criteria and improves load transient response versus the 1 μF minimum, especially for pulsed loads like DSP burst operations.

Is the EN pin 5 V tolerant when VIN = 18 V?

No. The EN pin voltage rating is −0.3 V to V_IN + 0.3 V per Table 4. With VIN = 18 V, V_EN must stay ≤18.3 V. However, logic-high threshold is only 1.2 V min, so standard 3.3 V or 5 V GPIO can safely drive EN without level-shifting, provided V_EN does not exceed VIN + 0.3 V under any condition.

Does LDK320M-R require an input capacitor, and if so, what value?

While not strictly mandatory per datasheet, a 1 μF ceramic input capacitor placed close to the IN and GND pins is strongly recommended to suppress high-frequency noise and improve transient response. The device's stability and PSRR performance assume proper local input decoupling; omission may degrade line rejection and cause instability under fast input transients.