LD49100PU33R - 1A Ultra-Low Noise LDO, 3.3V Fixed | STMicroelectronics
MPN: LD49100PU33R ✓ 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 | $0.54 | $540.00 |
Drop-in alternatives for LD49100PU33R — same package, pin-to-pin compatible. Different-package parts requiring PCB rework are excluded.
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LD49100PU33R
✅ Drop-In✓ 99,999 In Stock
$0.54 / Unit
View Datasheet →LD49100PU12R
⚡ Same Package📋 Reference alternative (not in catalog)
LD49100PU18R
⚡ Same Package📋 Reference alternative (not in catalog)
LD49100PU33R Maximum Ratings & Electrical Characteristics
| Output Type | Fixed |
| Output Voltage | 3.3 V |
| Maximum Output Current | 1 A |
| Input Voltage Range | 2.5 V to 5.5 V |
| Dropout Voltage | 200 mV at 1 A |
| Output Noise | 12 µVrms (10 Hz to 100 kHz) |
| PSRR | 70 dB at 1 kHz |
| Quiescent Current | 30 µA |
| Thermal Resistance | 50 °C/W |
| Operating Temperature | -40°C to +125°C |
| Package | DFN-6 (2x2 mm) |
| Mounting Type | Surface Mount |
| MSL Level | 1 (unlimited) |
| RoHS Status | Compliant |
| Enable Pin | Yes (active-high) |
LD49100PU33R Pin Configuration
| Pin 1 | IN — Input supply voltage (2.5V to 5.5V) |
| Pin 2 | GND — Ground |
| Pin 3 | EN — Enable (active-high) |
| Pin 4 | NC — No connection |
| Pin 5 | OUT — Regulated 3.3V output |
| Pin 6 | NC — No connection |
Safe Operating Area (SOA) & Thermal Characteristics
No official SOA curve available for this component. Always operate within absolute maximum ratings specified in the datasheet. Ensure adequate cooling and derate as needed.
Typical Applications
LD49100PU33R is suitable for 6 applications: Portable Battery-Powered Devices, Audio Codec Power Supply, RF Transceiver Power, Industrial Sensor Interfaces, Medical Monitoring Devices, IoT Smart Home Devices.
Portable Battery-Powered Devices
The LD49100PU33R's low quiescent current of 30 µA and 1A output capability make it ideal for battery-powered devices such as smartphones, wearables, and IoT sensors. Its low dropout voltage of 200 mV ensures efficient operation even as the battery discharges. The fixed 3.3V output simplifies design, and the enable pin allows power gating to extend battery life. In a typical application, the LDO is placed between the battery (3.7V Li-ion) and the system's 3.3V rail, providing a stable supply for microcontrollers, sensors, and wireless modules. The high PSRR of 70 dB at 1 kHz filters out noise from the battery and switching regulators, ensuring reliable operation of sensitive components.
Recommended
Audio Codec Power Supply
The LD49100PU33R's ultra-low output noise of 12 µVrms and high PSRR make it an excellent choice for powering audio codecs and DACs. In an audio application, the LDO provides a clean 3.3V rail to the codec's analog supply pins, minimizing noise that could degrade the signal-to-noise ratio. The low dropout voltage ensures the codec operates correctly even when the input supply is close to 3.5V. The enable pin can be used to mute the audio path during power-up or shutdown, preventing pops and clicks. Compared to switching regulators, the LDO eliminates switching noise, which is critical for high-fidelity audio reproduction. The DFN-6 package's small footprint is ideal for compact audio devices like headphones and portable speakers.
Recommended
RF Transceiver Power
The LD49100PU33R is well-suited for powering RF transceivers, where noise on the supply rail can directly affect phase noise and receiver sensitivity. Its 12 µVrms noise and 70 dB PSRR at 1 kHz ensure a clean 3.3V rail for VCOs, PLLs, and RF amplifiers. The low quiescent current helps extend battery life in portable RF devices like Bluetooth beacons and remote controls. In a typical RF application, the LDO is placed between the battery and the transceiver's VCC pin, with a 1µF input capacitor and a 2.2µF output capacitor for stability. The enable pin allows the RF section to be powered down when not in use, reducing overall power consumption.
Recommended
Industrial Sensor Interfaces
In industrial applications, the LD49100PU33R provides a stable 3.3V rail for sensors, ADCs, and microcontrollers operating in harsh environments. Its wide operating temperature range of -40°C to +125°C ensures reliable performance in extreme conditions. The high PSRR rejects noise from industrial power lines and motor drivers, maintaining accurate sensor readings. The low dropout voltage allows operation from a 3.6V supply, which is common in 3.3V systems with a diode drop. The enable pin can be used to power down sensors when not in use, saving energy in battery-powered industrial monitors. The DFN-6 package's small size is suitable for space-constrained industrial PCBs.
Recommended
Medical Monitoring Devices
The LD49100PU33R is ideal for medical monitoring devices such as wearable heart rate monitors and glucose meters, where low noise and low power are critical. Its 12 µVrms noise ensures accurate signal acquisition from biosensors, while the 30 µA quiescent current extends battery life. The fixed 3.3V output simplifies design, and the enable pin allows the device to enter a low-power sleep mode. In a typical application, the LDO powers the analog front-end and microcontroller, providing a clean supply that does not interfere with sensitive measurements. The small DFN-6 package is suitable for compact wearable designs.
Recommended
IoT Smart Home Devices
The LD49100PU33R is well-suited for IoT smart home devices like smart thermostats, door locks, and environmental sensors. Its low quiescent current and high efficiency at light loads make it ideal for battery-powered or energy-harvesting devices. The fixed 3.3V output is compatible with common IoT microcontrollers and wireless modules. The enable pin allows the device to be completely powered down when not in use, reducing standby power consumption. The high PSRR ensures stable operation even when the input supply has ripple from a wall adapter or solar panel. The compact DFN-6 package fits easily into small smart home devices.
Recommended
Recommended Products Summary
Engineering reference data for LD49100PU33R — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | LD49100PU12R | LD49100PU18R | TLV75533P | AP2127K-3.3TRG1 |
|---|---|---|---|---|---|
| Package | DFN-6 (2x2 mm) | DFN-6 (2x2 mm) - same | DFN-6 (2x2 mm) - same | X2SON-4 (1x1 mm) - different | SOT-23-5 - different |
| Brand | STMicroelectronics | STMicroelectronics | STMicroelectronics | Texas Instruments | Diodes Incorporated |
| Output Voltage | 3.3V | 1.2V | 1.8V | 3.3V | 3.3V |
| Output Current | 1A | 1A | 1A | 0.5A | 0.3A |
| Dropout Voltage | 200mV at 1A | 200mV at 1A | 200mV at 1A | 250mV at 0.5A | 300mV at 0.3A |
| Output Noise | 12 µVrms | 12 µVrms | 12 µVrms | 20 µVrms | 30 µVrms |
| PSRR at 1kHz | 70 dB | 70 dB | 70 dB | 65 dB | 60 dB |
| Quiescent Current | 30 µA | 30 µA | 30 µA | 25 µA | 50 µA |
Key Differentiators
- Ultra-low output noise of 12 µVrms (vs AP2127K-3.3TRG1)
- Higher output current of 1A (vs TLV75533P)
- Same-brand family compatibility (vs LD49100PU12R)
Design Notes
Place input and output capacitors as close to the IC pins as possible. Use a 1µF ceramic capacitor on the input and a 2.2µF ceramic capacitor on the output for stability. For optimal noise performance, add a 0.1µF capacitor in parallel with the output capacitor to filter high-frequency noise.
At VIN=5V, VOUT=3.3V, and 1A load, power dissipation is 1.7W. The DFN-6 package has a thermal resistance of 50°C/W, resulting in a junction temperature rise of 85°C above ambient. For reliable operation at high ambient temperatures, ensure adequate copper area on the PCB or use a heatsink.
Do not exceed the maximum input voltage of 5.5V. Ensure the enable pin is not left floating; tie it to VIN if not used. The output capacitor must have a minimum capacitance of 2.2µF to maintain stability. Avoid using capacitors with high ESR, as they can cause oscillation.
Compliance Information
RoHS compliant per STMicroelectronics product page. Not AEC-Q100 qualified; for automotive, consider the LD49100PU33R-Q1 variant if available.
