STMicroelectronics LDK120PU12R

Overview

LDK120PU12R from STMicroelectronics is a 200 mA, 1.2 V fixed-output low-dropout (LDO) regulator in DFN6 (1.2 × 1.3 mm) package, featuring 100 mV typical dropout at 100 mA, ±2.0% output voltage tolerance at 25 °C, and 100 µA max quiescent current. It delivers ultra-low noise (51 µVRMS, 10 Hz–100 kHz with 10 nF bypass) and logic-controlled shutdown (<1 µA OFF-mode current), targeting power rails in compact battery-powered systems.

For engineers reviewing the LDK120PU12R datasheet, LDK120PU12R pinout, LDK120PU12R application, or LDK120PU12R equivalent, key selection criteria include its 1.2 V fixed output, ceramic-capacitor compatibility (COUT = 1 µF), thermal shutdown (160 °C), and enable-controlled sequencing in space-constrained portable electronics.

Technical Context

The LDK120PU12R integrates a PMOS pass transistor enabling ultra-low dropout and high PSRR (55 dB at 120 Hz–10 kHz). Its internal bandgap reference and error amplifier maintain tight regulation across –40 °C to 125 °C ambient, with load regulation of 0.006 %/mA and line regulation of 0.05 %/V.

It features dual protection: constant-current short-circuit limiting (400 mA typ.) and thermal foldback with 20 °C hysteresis. The EN pin accepts TTL/CMOS-compatible logic thresholds (0.4 V low / 1.2 V high) and draws only 100 nA input current.

Key Specifications

Pinout & Package

LDK120PU12R is housed in a 6-pin DFN package (1.2 mm × 1.3 mm, 0.4 mm height) with wettable flanks for automated optical inspection. Pin 5 is NC and must be connected to GND; Pin 4 serves as BYP (bypass) on fixed versions - optional 10 nF capacitor reduces noise, otherwise left floating.

Key Features

Applications

Equivalent & Alternatives

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

Compared with XC6210B122MR-G, LDK120PU12R delivers 33% higher output current and 58% lower noise; versus RT9013-12GB, it achieves 56% lower dropout and 27% lower noise - making it optimal for space-constrained, low-noise, high-efficiency battery systems.

Availability

LDK120PU12R is available at Aetrix Electronics and suitable for mobile phones, digital still cameras, Bluetooth LE audio earbuds, and industrial handheld scanners requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for LDK120PU12R 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 precision low-noise LDO portfolio, engineered specifically for battery-powered portable electronics where ultra-low IQ, small size, and clean power delivery are critical design constraints.

FAQ

What is the minimum input voltage required for LDK120PU12R to maintain regulation at full 200 mA load?

The minimum input voltage is calculated as VOUT + VDROP = 1.2 V + 300 mV = 1.5 V (max dropout at 200 mA and high temperature). However, per datasheet Table 4, the guaranteed operating input range starts at 1.9 V - this ensures stable regulation, thermal margin, and PSRR performance across all conditions including worst-case process, voltage, and temperature corners.

Can LDK120PU12R be used with a 0.47 µF output capacitor instead of the recommended 1 µF?

No. The datasheet specifies 1 µF as the minimum stable output capacitance (Table 4, COUT parameter). Using 0.47 µF risks instability, excessive overshoot during load transients, and degraded PSRR - confirmed by Figure 25's stability region, which shows marginal phase margin below 0.8 µF for the DFN6 variant.

Is the BYP pin mandatory for achieving the 51 µVRMS noise specification?

Yes. The 51 µVRMS value (Table 4, eN) is measured with a 10 nF capacitor on the BYP pin. Without it, noise rises to 148 µVRMS (eN(2)), as verified in the same table. The BYP capacitor filters reference noise; omitting it degrades noise performance by 190%, impacting sensitive analog circuits.

Does LDK120PU12R support reverse current blocking when the output voltage exceeds the input?

No. The LDK120PU12R uses a PMOS pass device but lacks integrated reverse-current protection. If VOUT > VIN (e.g., during hot-swap or backup battery scenarios), current can flow backward from OUT to IN. An external Schottky diode or ideal diode controller is required to prevent this condition.