SR5E1E3 - 5V 1A LDO Voltage Regulator | STMicroelectronics
MPN: SR5E1E3 ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $0.85 | $0.85 |
| 10 | $0.76 | $7.60 |
| 100 | $0.68 | $68.00 |
| 500 | $0.61 | $305.00 |
| 1,000 | $0.55 | $550.00 |
SR5E1E3 Overview
An LDO (Low-Dropout) linear regulator is a type of voltage regulator that maintains a stable output voltage even when the input voltage is very close to the output voltage. Unlike standard linear regulators, LDOs can operate with a smaller input-to-output voltage differential, reducing power dissipation and improving efficiency in battery-powered or low-headroom applications. LDOs are a subset of linear regulators, which in turn are a type of voltage regulator, a fundamental building block in power management ICs. They are widely used to provide clean, low-noise supply rails for analog, digital, and RF circuits.
Key features of the SR5E1E3 include a fixed 5V output, a maximum output current of 1A, and a dropout voltage of 500mV at full load. The device also offers internal current limiting and thermal shutdown protection, ensuring safe operation under fault conditions. The TO-252 package has a thermal resistance of 62°C/W, allowing it to dissipate up to 1.6W at 25°C ambient without external heatsinking. The operating temperature range is -40°C to +125°C, making it suitable for harsh environments.
The SR5E1E3 uses a PNP pass transistor architecture, which provides low dropout voltage and stable operation. The internal bandgap reference ensures accurate output voltage regulation across temperature and load variations. The device is designed for simplicity, requiring only input and output capacitors for stable operation. The fixed output voltage eliminates the need for external resistor dividers, reducing component count and board space.
Typical applications include powering microcontrollers, sensors, and small logic circuits in industrial control systems, automotive electronics, and consumer appliances. The wide input voltage range allows it to be used in 12V and 24V bus systems, providing a regulated 5V rail for digital circuitry. The low dropout voltage ensures efficient operation even when the input voltage is close to 5V, such as in battery-powered devices.
When designing with the SR5E1E3, ensure adequate input and output capacitance (typically 10µF) to maintain stability and transient response. The thermal pad of the TO-252 package should be connected to a large copper area on the PCB to enhance heat dissipation. For high-current applications, verify that the junction temperature remains within the safe operating range by calculating power dissipation and thermal resistance.
Drop-in alternatives for SR5E1E3 — same package, pin-to-pin compatible. Different-package parts requiring PCB rework are excluded.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
L78M05CDT-TR
✅ Drop-In ⚠️ Specs Unverified📋 Reference alternative (not in catalog)
MC7805CDT
✅ Drop-In ⚠️ Specs Unverified📋 Reference alternative (not in catalog)
SR5E1E3 Maximum Ratings & Electrical Characteristics
| Output Type | Fixed |
| Output Voltage | 5 V |
| Maximum Output Current | 1 A |
| Input Voltage Range | 6 V to 26 V |
| Dropout Voltage | 500 mV at 1 A |
| Quiescent Current | 5 mA |
| Line Regulation | 10 mV |
| Load Regulation | 20 mV |
| PSRR | 60 dB at 1 kHz |
| Output Noise | 50 µVrms (10 Hz to 100 kHz) |
| Operating Temperature Range | -40°C to +125°C |
| Package | TO-252 (DPAK) |
| Mounting Type | Surface Mount |
| Thermal Resistance (θJA) | 62 °C/W |
| RoHS Status | Compliant |
SR5E1E3 Pin Configuration
| Pin 1 | GND — Ground |
| Pin 2 | VIN — Input voltage |
| Pin 3 | VOUT — Output voltage |
| Pin 4 | TAB — Thermal pad (connected to GND) |
Typical Applications
SR5E1E3 is suitable for 6 applications: Industrial Control Systems, Automotive Electronics, Consumer Appliances, Battery-Powered Devices, Networking Equipment, Test and Measurement.
Industrial Control Systems
The SR5E1E3 provides a stable 5V rail for microcontrollers, sensors, and logic circuits in industrial environments. Its wide input voltage range (6V to 26V) allows it to be powered from 12V or 24V industrial buses, while the low dropout voltage ensures efficient operation even with fluctuating input supplies. The device's thermal shutdown and current limiting protect against overloads, making it reliable for continuous operation in factory automation, PLCs, and motor control units. The TO-252 package with exposed pad facilitates heat dissipation, enabling operation at ambient temperatures up to 125°C. For best performance, place a 10µF ceramic capacitor at the input and output to maintain stability and transient response. The SR5E1E3's low quiescent current (5mA) is beneficial in energy-conscious designs, reducing standby power consumption.
Recommended
Automotive Electronics
In automotive applications, the SR5E1E3 can regulate the vehicle's 12V battery voltage down to a clean 5V for infotainment systems, sensors, and control modules. The device's operating temperature range of -40°C to +125°C ensures reliable operation in harsh automotive environments. The wide input voltage range accommodates voltage transients during cranking and load dumps, while the internal current limiting and thermal shutdown protect the regulator and downstream circuitry. The low dropout voltage (500mV) minimizes power dissipation, which is critical in under-hood applications where heat is a concern. For automotive designs, it is recommended to add a reverse polarity protection diode and a transient voltage suppressor at the input to handle load dump conditions. The SR5E1E3 is not AEC-Q100 qualified, so for strict automotive compliance, consider using a qualified alternative such as the TPS7A1601-Q1.
Recommended
Consumer Appliances
The SR5E1E3 is ideal for consumer appliances such as washing machines, refrigerators, and smart home devices that require a regulated 5V supply for control boards and user interfaces. Its low cost and small footprint make it suitable for high-volume production. The device's fixed 5V output simplifies design, eliminating the need for external resistor dividers. The wide input voltage range allows it to be powered from a variety of AC-DC adapters or battery packs. The low quiescent current helps meet energy efficiency standards, such as Energy Star, by reducing standby power consumption. In appliances with motors, the SR5E1E3 can provide a clean supply for the microcontroller while the motor is driven by a separate power stage, ensuring stable operation despite motor-induced noise. For optimal performance, use a 10µF capacitor on the output to handle transient loads.
Recommended
Battery-Powered Devices
The SR5E1E3's low dropout voltage (500mV) and low quiescent current (5mA) make it suitable for battery-powered devices where efficiency is critical. It can regulate a 6V to 9V battery down to a stable 5V for portable instruments, handheld meters, and wireless sensors. The low dropout voltage allows the battery to discharge deeper before the regulator drops out, extending battery life. The device's thermal shutdown and current limiting protect the battery and load from faults. In battery-powered designs, it is important to minimize quiescent current to maximize runtime; the SR5E1E3's 5mA quiescent current is acceptable for moderate power applications but may be too high for ultra-low-power designs. For such cases, consider a low-IQ LDO like the TPS7A02. The TO-252 package is relatively large for portable devices, so for space-constrained designs, a smaller package alternative may be preferred.
Recommended
Networking Equipment
In networking equipment such as routers, switches, and IoT gateways, the SR5E1E3 provides a clean 5V rail for processors, PHY chips, and interface circuits. The device's high PSRR (60dB at 1kHz) helps reject noise from switching power supplies, ensuring stable operation of sensitive communication circuits. The wide input voltage range allows it to be powered from a 12V or 24V supply commonly used in networking gear. The low dropout voltage reduces power dissipation, which is important in densely packed enclosures with limited airflow. For networking applications, it is recommended to add a ferrite bead in series with the input to suppress high-frequency noise. The SR5E1E3's thermal shutdown protection prevents damage in case of a fault, enhancing system reliability. The TO-252 package is suitable for PCB designs with moderate power dissipation.
Recommended
Test and Measurement
The SR5E1E3 is used in test and measurement equipment to provide a stable 5V reference for analog-to-digital converters, operational amplifiers, and digital logic. Its low output noise (50µVrms) and high PSRR ensure accurate measurements by minimizing power supply-induced errors. The wide input voltage range allows it to be powered from a bench supply or battery. The device's thermal shutdown and current limiting protect the equipment from faults. In precision measurement applications, it is recommended to use a low-noise LDO with even lower noise, such as the TPS7A4701, but the SR5E1E3 offers a cost-effective solution for general-purpose instruments. The TO-252 package is easy to solder and provides adequate thermal performance for moderate power dissipation. For best accuracy, place the output capacitor close to the load and use a star-ground layout to minimize noise coupling.
Recommended
Recommended Products Summary
Engineering reference data for SR5E1E3 — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | L78M05CDT-TR | MC7805CDT | L78S05CV |
|---|---|---|---|---|
| Package | TO-252 (DPAK) | TO-252 (DPAK) - same | TO-252 (DPAK) - same | TO-220 - different |
| Brand | STMicroelectronics | STMicroelectronics | onsemi | STMicroelectronics |
| Output Voltage | 5V | 5V | 5V | 5V |
| Maximum Output Current | 1A | 500mA | 1A | 2A |
| Input Voltage Range | 6V to 26V | 7V to 25V | 7V to 25V | 7V to 25V |
| Dropout Voltage | 500mV at 1A | 2V at 500mA | 2V at 1A | 2V at 2A |
| Quiescent Current | 5mA | 6mA | 6mA | 8mA |
| Operating Temperature Range | -40°C to +125°C | -40°C to +125°C | 0°C to +125°C | 0°C to +125°C |
Key Differentiators
- Low dropout voltage of 500mV at 1A (vs L78M05CDT-TR)
- Higher output current of 1A (vs L78M05CDT-TR)
- Wider input voltage range of 6V to 26V (vs MC7805CDT)
Design Notes
The SR5E1E3 in TO-252 package has a thermal resistance of 62°C/W. At maximum load (1A) with a 12V input and 5V output, power dissipation is (12V-5V)*1A = 7W, which would cause a junction temperature rise of 434°C, far exceeding the maximum rating. Therefore, for high current or high input voltage, a heatsink or a larger copper area is essential. For example, at 1A with 8V input, dissipation is 3W, resulting in a 186°C rise, still too high. It is recommended to keep power dissipation below 1W for reliable operation without external heatsinking, or use a heatsink and ensure adequate airflow.
Place a 10µF ceramic capacitor at the input and output, as close to the pins as possible. The input capacitor should be placed between VIN and GND, and the output capacitor between VOUT and GND. Use a low-ESR capacitor for better transient response. The thermal pad (TAB) should be soldered to a large copper area on the PCB to enhance heat dissipation. For best performance, use a ground plane and keep the trace lengths short to minimize parasitic inductance.
Do not exceed the maximum input voltage of 26V. Ensure the input voltage is at least 6V to maintain regulation. The output capacitor must have a minimum capacitance of 10µF for stability; using a smaller capacitor may cause oscillation. Avoid reverse polarity on the input, as the device does not have built-in reverse polarity protection. For automotive applications, add a transient voltage suppressor at the input to handle load dump transients.
Compliance Information
RoHS compliant per STMicroelectronics product page. Not AEC-Q100 qualified. Halogen-free status not specified in available data.
