LD49100PU33R - 1A Ultra-Low Noise LDO, 3.3V Fixed | STMicroelectronics
MPN： LD49100PU33R ✓ 啟用中LD49100PU33R 概覽
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. It achieves this by operating its pass transistor in the linear region, dissipating excess power as heat. LDOs are essential in power management hierarchies, sitting between switching regulators and sensitive loads to provide clean, low-noise power rails. They are widely used in battery-powered devices, audio equipment, RF transceivers, and precision analog circuits where noise and ripple rejection are critical.
Key features of the LD49100PU33R include an output noise of 12 µVrms (10 Hz to 100 kHz), a power supply rejection ratio (PSRR) of 70 dB at 1 kHz, and a quiescent current of 30 µA. The device also features an enable pin for power sequencing, internal current limiting, and thermal shutdown protection. The DFN-6 package offers a thermal resistance of 50°C/W, enabling efficient heat dissipation in compact designs.
The LD49100PU33R utilizes a CMOS architecture with a precision bandgap reference, achieving excellent line and load regulation. The high PSRR minimizes ripple from upstream switching converters, making it ideal for noise-sensitive analog and RF signal chains. The low quiescent current extends battery life in portable devices, while the wide input range supports various supply rails.
Typical applications include powering audio codecs, MEMS sensors, RF transceivers, and microcontroller I/O rails. The fixed 3.3V output simplifies design by eliminating external resistor dividers, and the enable pin allows controlled power-up sequencing in multi-rail systems.
When designing with this device, ensure adequate input-to-output voltage headroom to maintain regulation under all load conditions. Place input and output capacitors close to the pins, and use a 1µF ceramic capacitor on the input and a 2.2µF ceramic capacitor on the output for stability.
直接替換替代品，適用於 LD49100PU33R — 相同封裝，腳位對腳位相容。需重新設計 PCB 的不同封裝零件不列入。
LD49100PU33R
✅ 直接替換聯絡詢價
查看資料表 →LD49100PU12R
⚡ 相同封裝 ⚠️ 規格未經驗證📋 參考替代品（不在目錄中）
LD49100PU18R
⚡ 相同封裝 ⚠️ 規格未經驗證📋 參考替代品（不在目錄中）
LD49100PU33R 最大額定值與電氣特性
| 輸出類型 | Fixed |
| 輸出電壓 | 3.3 V |
| 最大輸出電流 | 1 A |
| 輸入電壓範圍 | 2.5 V to 5.5 V |
| 壓降電壓 | 200 mV at 1 A |
| 輸出雜訊 | 12 µVrms (10 Hz to 100 kHz) |
| PSRR | 70 dB at 1 kHz |
| 靜態電流 | 30 µA |
| 熱阻 | 50 °C/W |
| 工作溫度 | -40°C to +125°C |
| 封裝 | DFN-6 (2x2 mm) |
| 安裝類型 | Surface Mount |
| MSL 等級 | 1 (unlimited) |
| RoHS 狀態 | Compliant |
| 致能腳位 | Yes (active-high) |
LD49100PU33R 腳位配置
| 腳位 1 | IN — Input supply voltage (2.5V to 5.5V) |
| 腳位 2 | GND — Ground |
| 腳位 3 | EN — Enable (active-high) |
| 腳位 4 | NC — No connection |
| 腳位 5 | OUT — Regulated 3.3V output |
| 腳位 6 | NC — No connection |
典型應用
LD49100PU33R 適用於 6 應用s: 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.
推薦
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.
推薦
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.
推薦
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.
推薦
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.
推薦
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.
推薦
推薦產品摘要
工程參考資料，適用於 LD49100PU33R — 比較、設計指引及合規資訊。
選型指南
與替代品比較
| 參數 | 本產品 | 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 |
主要差異化特點
- Ultra-low output noise of 12 µVrms (對比AP2127K-3.3TRG1)
- Higher output current of 1A (對比TLV75533P)
- Same-brand family compatibility (對比LD49100PU12R)
設計說明
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.
合規資訊
RoHS compliant per STMicroelectronics product page. Not AEC-Q100 qualified; for automotive, consider the LD49100PU33R-Q1 variant if available.
