MCP1825T-ADJE/DC 3.3V LDO Voltage Regulator: Technical Specifications and Application Circuit Design
The MCP1825T-ADJE/DC is a high-performance, low-dropout (LDO) voltage regulator from Microchip Technology, designed to deliver a fixed 3.3V output from a higher input voltage source. Renowned for its low dropout voltage and high-accuracy output, it is an ideal choice for powering sensitive digital and analog loads in a wide array of applications, including embedded systems, consumer electronics, and portable devices.
Key Technical Specifications
The defining characteristics of the MCP1825T-ADJE/DC make it a robust solution for stable power management:
Output Voltage: Fixed at 3.3V with a high accuracy of ±0.5% under specified conditions.
Output Current: Capable of delivering up to 500 mA of continuous output current.
Dropout Voltage: Features an exceptionally low dropout voltage of 210 mV (typical) at 500 mA load. This allows it to continue regulating even when the input voltage drops very close to the output level, enhancing efficiency and extending battery life in portable applications.
Low Quiescent Current: The device consumes a very low ground current of 120 µA (typical), which is crucial for power-sensitive designs.
High Power Supply Rejection Ratio (PSRR): Offers excellent noise rejection, typically 70 dB at 1 kHz, making it suitable for powering noise-sensitive components like RF transceivers and analog sensors.
Protection Features: Includes built-in overcurrent protection and thermal shutdown, safeguarding the regulator and the downstream circuitry from damage under fault conditions.
Package: Available in a space-efficient SOT-223 package, providing a good balance of size and thermal performance.
Typical Application Circuit Design
Implementing the MCP1825T-ADJE/DC is straightforward, requiring only a few external components for a complete regulation solution. A standard application circuit is shown below.
```
VIN (4.0V - 6.0V)
│
├───────┐
│ │
+++ +++ C_IN
| | 10µF | |
| | | |
+++ +++
│ │
└───┬───┘
│
┌────┴────┐
│ VIN GND │◄───┬─────────┬─── GND
│ │ │ +++
│ MCP │ │ | | C_OUT
│ 1825T │ │ | | 10µF
│ │ │ +++
│ VOUT SHDN│ │ │
└────┬────┘ │ │
│ │ │
+++ +++ │
| | 100nF | | │
| | | | │
+++ +++ │
│ │ │
├─────────┴─────────┴─── GND
│
VOUT (3.3V, 500mA max)
```
Circuit Design Explanation:
1. Input Capacitor (C_IN): A 10 µF ceramic capacitor is required between the VIN pin and ground. It should be placed as close as possible to the regulator pins to ensure stability and improve transient response. This capacitor helps to filter input noise and provides a local charge reservoir.
2. Output Capacitor (C_OUT): A 10 µF ceramic capacitor is required between the VOUT pin and ground. Like the input capacitor, it must be placed close to the regulator. This component is critical for loop stability and for handling fast load transients, ensuring a clean, stable output voltage.
3. Bypass Capacitor (Optional): A small 100 nF ceramic capacitor can be added directly at the load to further decouple high-frequency noise.
4. Shutdown Pin (SHDN): This active-low control pin allows an external microcontroller or logic circuit to turn the regulator on or off, reducing the total system power consumption to a minimum in standby mode. It can be tied directly to VIN if the shutdown feature is not used.
Thermal Considerations
For full-load operation (500 mA), the power dissipation (P_D = (V_IN - V_OUT) I_OUT) can become significant. The SOT-223 package's exposed thermal pad must be soldered to a sufficient copper area on the PCB to act as a heatsink, preventing the internal thermal shutdown circuit from activating.
ICGOOODFIND Summary
The MCP1825T-ADJE/DC stands out as a highly reliable and efficient 3.3V LDO regulator. Its combination of low dropout voltage, high output accuracy, and excellent noise performance makes it an exceptional choice for designers seeking to create clean and stable power rails for sensitive components. Ease of use, with minimal external part count, and integrated protection features further solidify its position as a go-to component for modern electronic designs.
Keywords:
1. LDO Regulator
2. 3.3V Output
3. Low Dropout Voltage
4. 500mA Output Current
5. PSRR
