STMicroelectronics LDK120C-R

Overview

LDK120C-R from STMicroelectronics is a 200 mA, low-quiescent-current, very-low-noise adjustable LDO regulator in SOT323-5L package, operating from 1.9 V to 5.5 V input with typical 100 mV dropout at 100 mA and ±2.0% output voltage accuracy at 25 °C - designed for precision power rail regulation in space-constrained battery-powered systems.

For engineers reviewing the LDK120C-R datasheet, LDK120C-R pinout, LDK120C-R application, or LDK120C-R equivalent, this page delivers verified technical context, real-world design meaning of key specs, validated pin functions, application-specific implementation value, and confirmed alternative options - all grounded in ST's DS9378 Rev 9 production data.

Technical Context

The LDK120C-R implements a PMOS pass transistor architecture enabling ultra-low dropout and stable operation with only 1 µF ceramic output capacitance. Its internal bandgap reference and error amplifier deliver tight load/line regulation (0.006 %/mA and 0.05 %/V) across –40 °C to 125 °C.

Logic-controlled enable (EN) provides precise shutdown with sub-1 µA quiescent current, while integrated thermal shutdown (160 °C) and short-circuit current limiting (400 mA typ.) ensure robust fault protection without external components.

Key Specifications

Pinout & Package

LDK120C-R is packaged in SOT323-5L (1.8 × 2.0 mm, 0.95 mm pitch), a surface-mount, lead-free, RoHS-compliant package optimized for high-density portable PCB layouts.

Key Features

Applications

Equivalent & Alternatives

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

Compared with XC6210B122MR-G, LDK120C-R delivers 33% higher output current and 40% lower dropout, trading off some noise floor for broader application flexibility; versus ADM7172ACPZ-1.2-R7, it offers identical current rating in a 40% smaller package but with higher noise - making it optimal for cost- and space-constrained designs where 148 µV_RMS is acceptable.

Availability

LDK120C-R is available at Aetrix Electronics and suitable for mobile phones, digital still cameras, portable medical devices, and industrial handheld scanners requiring stable component supply with full production lifecycle support through July 2026.

Supply support for LDK120C-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 microcontrollers, power management ICs, sensors, and analog products for automotive, industrial, and consumer markets.

The LDK120 series belongs to ST's ultra-low-noise, low-I_Q LDO portfolio - engineered specifically for battery-powered portable electronics where efficiency, noise immunity, and small-footprint power integrity are non-negotiable.

FAQ

What output voltage range can be set using the LDK120C-R in adjustable configuration?

The LDK120C-R supports an output voltage range from 0.8 V to (V_IN – V_DROP), where V_DROP is typically 100 mV at 100 mA. With V_IN up to 5.5 V, this enables outputs up to ~5.4 V. The ADJ pin has a precise 800 mV ±2% reference, so V_OUT = 0.8 V × (1 + R1/R2). Fixed versions (e.g., LDK120C25R) are also available for common voltages.

Can the LDK120C-R operate stably with less than 1 µF output capacitance?

No - ST specifies minimum 1 µF ceramic output capacitance (X5R/X7R, ESR < 1 Ω) for guaranteed stability across temperature and load. Reducing C_OUT below 1 µF risks oscillation or poor transient response, as confirmed by Figure 25 and Figure 26 in DS9378 Rev 9. No derating or exception is documented for SOT323-5L.

Is the BYP pin used in the LDK120C-R adjustable version?

No - the LDK120C-R is the adjustable version (per Table 12 marking "KAD"), and Pin 4 is designated ADJ, not BYP. The BYP function applies only to fixed-output variants (e.g., LDK120C25R), where Pin 4 serves as a noise-reduction bypass terminal. In LDK120C-R, Pin 4 is the feedback adjust node and must be connected to the R1/R2 divider.

Does the LDK120C-R require an input capacitor, and if so, what value?

Yes - a 1 µF ceramic input capacitor (C_IN) is required per the Typical Application schematic (Figure 4) and Section 3 of DS9378 Rev 9. It must be placed close to the IN and GND pins to suppress high-frequency noise and prevent instability due to PCB trace inductance. X5R or X7R dielectric is recommended for stable capacitance across voltage and temperature.