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LDK220 LDO Voltage Regulators Specifications, Features, Pinout, and Applications

Update time : 2026-02-02 11:57:59

The LDK220 series of low-dropout linear regulators (LDOs) is a high-performance device designed specifically for low-power consumption and high-precision voltage regulation, widely used in scenarios such as consumer electronics, industrial control, and portable devices. Its core advantages lie in a wide input voltage range, low dropout voltage, and excellent noise suppression capability, enabling it to provide stable and reliable power supply for sensitive circuits.
As an integrated LDO, the LDK220 not only supports multiple fixed output voltage options but also features adjustable output functionality to adapt to different load requirements. Additionally, it incorporates built-in safety mechanisms such as overcurrent protection and thermal shutdown, enhancing system reliability. This article will comprehensively analyze the performance advantages and practical value of the LDK220 from aspects including electrical specifications, core features, pin definitions, and typical applications, providing a reference for engineers in component selection and circuit design.

LDK220 Overview

The LDK220 is a low-dropout (LDO) voltage regulator designed by STMicroelectronics, offering a maximum output current of 200 mA with an input voltage range of 2.5 V to 13.2 V. It features ultra-low dropout voltage, low quiescent current, and low noise, making it ideal for power-sensitive applications such as battery-powered devices. The device includes built-in protection mechanisms (current limiting and thermal shutdown) and supports both fixed and adjustable output voltages, with flexible packaging options to suit diverse design needs.

LDK220 Features

Wide input voltage range: 2.5 V to 13.2 V.
Ultra-low dropout voltage: 100 mV (typical) at 100 mA load.
Low quiescent current: 55 µA (typical) in active mode; 1 µA in shutdown mode.
Low noise performance: 20 µV RMS/V (typical) across 10 Hz to 100 kHz.
Precise output voltage: ±2.0% tolerance at 25°C, ±3.0% over -40°C to 125°C.
200 mA guaranteed output current.
Flexible output voltages: Fixed versions from 1.2 V to 12 V (100 mV steps) or adjustable.
Logic-controlled shutdown: Enabled via the EN pin, with output discharge function when disabled.
Stable with small capacitors: Compatible with 1 µF ceramic output capacitors.
Built-in protection: Internal current limiting and thermal shutdown (160°C with 20°C hysteresis).
Wide operating temperature: -40°C to 125°C.
Multiple packages: SOT23-5L, SOT323-5L, SOT-89, and DFN6-1.2x1.3.

LDK220 Pinout

Pin configurations vary by package; key details are as follows:

Package	Pins & Functions
SOT23-5L/SOT323-5L	1 (IN): Input voltage; 2 (GND): Common ground; 3 (EN): Enable (low = shutdown, high = active); 4 (ADJ/NC): Adjustable pin (or no-connect for fixed versions); 5 (OUT): Output voltage.
DFN6-1.2x1.3	1 (OUT): Output voltage; 2 (N/C): No-connect; 3 (ADJ/NC): Adjustable pin (or no-connect); 4 (EN): Enable; 5 (GND): Ground; 6 (IN): Input voltage.
SOT-89	1 (OUT): Output voltage; 2 (GND): Ground; 3 (IN): Input voltage.

LDK220 Absolute Maximum Ratings

Parameter	Value	Unit
DC input voltage (VIN)	-0.3 to 14	V
DC output voltage (VOUT)	-0.3 to VIN + 0.3	V
Enable voltage (VEN)	-0.3 to VIN + 0.3	V
ADJ pin voltage	-0.3 to 2	V
Output current (IOUT)	Internally limited	mA
Power dissipation (PD)	500	mW
Storage temperature	-65 to 150	°C
Operating junction temp	-40 to 125	°C

LDK220 Block Diagram

The LDK220’s architecture includes core functional blocks for voltage regulation and protection:

The LDK220 features two block diagram variants: fixed-output and adjustable-output, sharing core functional modules with design differences for voltage flexibility.
Fixed-Output Version
The fixed topology integrates:

Bandgap Reference: Generates a stable internal voltage reference for regulation.
Error Amplifier: Compares the feedback voltage (from an internal divider) to the reference, adjusting the power transistor to maintain a fixed output.
Power Transistor: Drives the load, delivering the regulated voltage.
Protection Circuits: Thermal shutdown (prevents overheating) and current limit (blocks overcurrent) ensure reliability.
Enable (EN) Pin: Controls chip activation/shutdown (shutdown mode draws ~1 µA).

Adjustable-Output Version
The adjustable variant modifies the feedback path:

Instead of an internal divider, an ADJ pin connects to external resistors (R₁/R₂), allowing custom output voltages via VO=VADJ×(1+R1/R2).
The error amplifier now references the ADJ pin’s voltage, enabling dynamic regulation across a wider range.

Both versions rely on the same power stage, protection mechanisms, and enable control. The modular design balances precision (via bandgap/reference), protection, and adaptability—critical for diverse power regulation needs.

LDK220 Typical Application Circuits

The LDK220’s typical application circuits are simple and flexible, with two topologies:
Fixed Output Version
Uses few components: a 1 µF ceramic input capacitor (C₍IN₎) to filter input noise, the LDK220 (with EN pin controlling on/off, drawing ~1 µA in shutdown), and a 1 µF ceramic output capacitor (C₍OUT₎) to smooth output ripples. Fixed models (e.g., LDK220C25R) output preset voltages (2.5V, 3.3V, etc.), suitable for sensor modules or low-power peripherals needing predefined voltages.
Adjustable Output Version
Adds two external resistors (R₁, R₂) to the ADJ pin, with output voltage calculated as VO=VADJ×(1+R1/R2) (V₍ADJ₎ is internal reference). R₁/R₂ (10 kΩ–100 kΩ) should minimize ADJ pin current impact. Input/output capacitors are also 1 µF ceramic. This enables custom voltages (1.8V–12V), ideal for industrial controls or prototyping needing voltage flexibility.
Both circuits balance simplicity and performance, fitting portable electronics to industrial systems.

LDK220 Applications

The LDK220, as a low-dropout (LDO) voltage regulator with low quiescent current, low noise, and robust performance, is well-suited for a range of applications. Its key features—such as wide input voltage range, low power consumption, stable output, and compact packaging—make it adaptable to diverse scenarios, including:
1. Battery-powered equipment
The LDK220’s ultra-low quiescent current (typical 55 µA in active mode, 1 µA in shutdown mode) and low dropout voltage (100 mV typ. @ 100 mA) minimize power loss, directly extending battery life. This makes it ideal for portable devices like wireless sensors, wearables, handheld instruments, and battery-operated consumer electronics, where energy efficiency is critical.
2. TVs and Set-top boxes
These devices require stable voltage regulation to power sensitive components (e.g., signal processing circuits, display drivers). The LDK220’s low noise (20 µV RMS/V for fixed versions) and excellent line/load regulation (0.001–0.05 %/V and 0.001–0.003 %/mA) ensure clean, consistent power, reducing signal interference and improving overall performance.
3. PCs and laptops
In compact computing devices, space constraints and diverse power requirements demand regulators with small form factors and flexible input ranges. The LDK220’s availability in tiny packages (e.g., DFN6-1.2x1.3) and wide input voltage (2.5–13.2 V) make it suitable for powering peripherals, chipsets, or low-power subsystems, while its thermal and current protection prevents damage from voltage spikes or overloads.
4. Industrial applications
Industrial environments often involve extreme temperatures (-40 °C to 125 °C) and harsh conditions. The LDK220’s wide operating temperature range, built-in thermal shutdown (160 °C) and current limiting, and stable performance under varying loads ensure reliability in industrial controls, sensors, and automation equipment. Its compatibility with small ceramic capacitors (1 µF) also simplifies design in space-constrained industrial setups.

LDK220 Package

The LDK220 is available in four compact packages, each with distinct thermal characteristics:

Package	Thermal Resistance (°C/W)	Key Dimensions
SOT23-5L	RthJA = 160; RthJC = 68	2.95 mm × 1.60 mm (typ.)
SOT323-5L	RthJA = 246; RthJC = 134	1.80 mm × 1.80 mm (typ.)
SOT-89	RthJA = 110; RthJC = 15	4.40 mm × 2.29 mm (typ.)
DFN6	RthJA = 237; RthJC = 104	1.20 mm × 1.30 m

LDK220 Manufacturer

The manufacturer of the LDK220 is STMicroelectronics, a globally leading provider of semiconductor solutions. The company focuses on providing innovative chips and technical support for multiple fields such as consumer electronics, industrial control, and automotive electronics, and its products are renowned for their reliability and high performance.

LDK220 vs. MIC5365

Both the LDK220 and MIC5365 are low-power LDOs targeting similar application scenarios, but the LDK220 holds a key advantage in energy efficiency. The LDK220 features an ultra-low quiescent current of 55 µA (typical) in active mode and only 1 µA in shutdown mode, which is significantly lower than the MIC5365’s higher quiescent current (typically 100+ µA). This makes the LDK220 far more suitable for battery-powered devices (e.g., portable sensors, wearables) where minimizing idle power consumption directly extends battery life. Additionally, the LDK220’s 100 mV dropout voltage (typical @ 100 mA load) matches the MIC5365’s low-dropout performance, ensuring efficient regulation even when the input voltage is close to the output voltage.

LDK220 vs. TLV707

The LDK220 and TLV707 both excel in low dropout voltage, making them suitable for applications with tight input-output voltage margins. However, the LDK220 outperforms the TLV707 in power supply rejection ratio (PSRR), a critical metric for noise-sensitive circuits. The LDK220’s fixed-output version achieves a typical PSRR of 55 dB across 120 Hz to 1 kHz, effectively suppressing input voltage ripples and ensuring a stable output. This advantage is particularly valuable in noise-sensitive scenarios such as analog sensor interfaces, audio circuits, or precision measurement equipment, where even small voltage fluctuations can degrade performance. The LDK220’s low noise floor (20 µV RMS/V for fixed versions) further reinforces its suitability for such applications, compared to the TLV707’s relatively higher noise levels.

LDK220 vs. LP2985

The LP2985 and LDK220 both support a maximum output current of ~200 mA, but the LDK220 offers better efficiency at low input voltages due to its lower dropout voltage. The LDK220 has a typical dropout voltage of 100 mV at 100 mA load, which is lower than the LP2985’s slightly higher dropout voltage (typically 150+ mV under similar conditions). This difference becomes critical in applications where the input voltage is only marginally higher than the output voltage (e.g., battery-powered devices with declining battery voltage), as the LDK220 minimizes power loss (P = I × V_dropout) and maintains higher efficiency. Additionally, the LDK220’s wider input voltage range (2.5 V to 13.2 V) provides more flexibility than the LP2985’s narrower range, adapting to a broader set of power sources.
In summary, the LDK220 distinguishes itself through its combination of ultra-low quiescent current, superior PSRR, and low dropout voltage, making it a standout choice for energy-efficient, noise-sensitive, and low-input-voltage applications compared to alternatives like the MIC5365, TLV707, and LP2985.

Popular LDK220 LDO Voltage Regulators

Products	Description
LDK220M33R	Fixed output voltage of 3.3V in an SOT23-5 package, suitable for compact designs requiring surface mounting.
LDK220M50R	Fixed output voltage of 5.0V in an SOT23-5 package, optimized for systems requiring a 5V output with low dropout.
LDK220M-R	Adjustable output voltage version in an SOT23-5 package, providing flexibility for variable voltage applications.
LDK220U33R	Fixed 3.3V output in an Ultra-Thin DFN-6 (2x2 mm) package, ideal for space-constrained, low-profile applications.
LDK220U50R	Fixed 5.0V output in an Ultra-Thin DFN-6 package, designed for compact, low-power systems needing a 5V supply.
LDK220PU33R	Fixed 3.3V output in a Flip-Chip 4-bump package, offering ultra-miniature size for high-density PCB designs.

Conclusion

The LDK220 is a versatile LDO regulator combining low power consumption, low noise, and robust protection, making it well-suited for battery-powered devices, consumer electronics, and industrial systems. Its flexible output options, compact packages, and stable performance with small capacitors ensure adaptability to diverse design requirements, solidifying its role as a reliable power management solution.

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