Microchip TC1264-3VDB 3V Voltage Regulator: Datasheet, Pinout, and Application Circuits

The Microchip TC1264-3VDB is a fixed 3.3V output, low-dropout (LDO) voltage regulator designed to deliver a clean, stable power supply for a wide range of applications. Known for its high accuracy, low quiescent current, and robust protection features, this regulator is a reliable choice for powering sensitive digital and analog circuits where noise and space are critical constraints.

This article provides a detailed overview of the TC1264-3VDB, covering its key specifications from the datasheet, pinout configuration, and practical application circuits.

Datasheet Overview and Key Specifications

The TC1264 is part of a family of LDO regulators from Microchip that offer excellent line and load regulation. The "3VDB" suffix specifically denotes a fixed 3.3V output in a SOT-223 package. Here are the critical specifications that define its performance:

Output Voltage: Fixed at 3.3V (±2% accuracy over line, load, and temperature).

Maximum Output Current: 500mA.

Dropout Voltage: Typically 500mV at full load (500mA). This low dropout voltage allows it to continue regulating even when the input voltage dips close to the output level, making it highly efficient.

Low Quiescent Current: Typically 85µA, which is crucial for battery-powered devices to extend operational life.

Protection Features: Includes over-current protection and thermal shutdown, safeguarding both the regulator and the downstream circuitry from damage.

Low Noise & High PSRR: Excellent for powering noise-sensitive components like RF modules, analog sensors, and precision ADCs.

Package: SOT-223, which offers a good balance of small size and power handling capability.

Pinout Configuration

The TC1264-3VDB comes in a 3+1 pin SOT-223 package. Understanding the pinout is essential for correct circuit design and PCB layout.

1. IN (Input Pin): This pin receives the unregulated input voltage. A ceramic input capacitor (typically 1µF to 10µF) must be placed as close as possible to this pin and GND to ensure stability and improve transient response.

2. GND (Ground Pin): The common ground reference for the regulator.

3. OUT (Output Pin): The regulated 3.3V output. A ceramic output capacitor (typically 1µF to 22µF) is required for stability and to improve load transient response.

4. Tab (Thermal Pad): The metal tab is internally connected to the GND pin. It provides the primary path for heat dissipation. For optimal performance, this tab must be soldered to a large copper pour (ground plane) on the PCB to act as a heatsink.

Application Circuits

The primary application of the TC1264-3VDB is to derive a stable 3.3V rail from a higher input voltage source, such as a 5V supply or a Li-Ion battery (3.7V - 4.2V). Its basic circuit is incredibly simple, requiring only two external capacitors.

1. Standard 3.3V Regulation Circuit

The most common application circuit is straightforward. The input voltage (e.g., 5V) is connected to the IN pin. The GND pin is connected to system ground. The output capacitor is placed on the OUT pin. The thermal tab is connected to the ground plane. This circuit is the workhorse for powering microcontrollers, ICs, and other logic circuits.

2. Battery-Powered Device Circuit

In a battery-powered application (e.g., a device using a 4.2V Li-Ion battery), the TC1264-3VDB's low dropout voltage and low quiescent current are key advantages. As the battery voltage discharges down to ~3.8V, the regulator continues to provide a stable 3.3V output, maximizing battery usage. The low quiescent current ensures minimal power is wasted when the device is in sleep or idle mode.

Design Considerations:

Thermal Management: When operating at high input voltages and near the maximum 500mA current, power dissipation (P_diss = (V_in - V_out) I_out) becomes significant. Proper PCB layout with a sufficient ground plane for the thermal tab is critical to prevent thermal shutdown.

Capacitor Selection: Always use stable, low-ESR ceramic capacitors. Tantalum capacitors can also be used but are not typically necessary for most modern designs.

ICGOODFIND Summary

The Microchip TC1264-3VDB is a highly reliable and efficient 500mA LDO voltage regulator. Its key strengths lie in its exceptional output accuracy, ultra-low dropout voltage, and comprehensive protection features. The minimal external component count (just two capacitors) and simple design make it an ideal choice for a vast array of applications, from consumer electronics and IoT devices to industrial control systems, where a clean and stable 3.3V power rail is required.

Keywords:

1. LDO Voltage Regulator

2. 3.3V Output

3. SOT-223 Package

4. Low Dropout Voltage

5. Thermal Shutdown