FDA903U - 1A, 35V Ultra-Low Noise LDO | Texas Instruments
料号： FDA903U ✓ 量产中| 数量 | 单价 | 小计 |
|---|---|---|
| 1 | $4.85 | $4.85 |
| 10 | $4.36 | $43.60 |
| 100 | $3.88 | $388.00 |
| 500 | $3.49 | $1,745.00 |
| 1,000 | $3.1 | $3,100.00 |
FDA903U 概述
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 is a key component in power management ICs, providing clean, low-noise power rails for sensitive analog and digital circuits. LDOs are essential in applications where switching noise from DC-DC converters would degrade performance, such as in audio, RF, and precision measurement systems.
Key features include 4.17 uVrms output noise (20 Hz to 100 kHz), 72 dB PSRR at 1 kHz, and a low dropout voltage of 200 mV at full 1A load. The device also offers 6.4 mA quiescent current, an active-high enable pin for power sequencing, and thermal shutdown protection. The VQFN-20 package provides a thermal resistance of 31.4 C/W, enabling compact designs without external heatsinking at moderate power levels.
The FDA903U utilizes a bipolar architecture with a precision bandgap reference, achieving noise performance comparable to discrete reference designs while maintaining regulator simplicity. The high PSRR minimizes ripple from upstream switching converters, making it suitable for noise-sensitive analog and RF signal chains where clean power rails are critical.
Typical applications include high-end audio DAC power supplies, PLL/VCO power rails in RF transceivers, precision ADC/DAC reference buffering, and test and measurement instrumentation. The wide input range also supports industrial 24V bus systems with adequate headroom.
When designing with this device, ensure adequate input-to-output voltage headroom to maintain regulation under all load conditions. The enable pin allows sequential power-up in multi-rail systems, which is essential for processors requiring specific rail sequencing.
直接替换替代料： FDA903U ——相同封装，引脚兼容。需要 PCB 改动的不同封装料号已排除。
本系列中的变体
可与以下型号直接替换的同系列型号： FDA903U （相同外形与封装尺寸） ——差异在于 Package, Enable Pin, Input Voltage Range, MSL Level, Output Type.
快速对比工具——选择替代料号进行并排对比：
TPS7A4700RGWR
✅ 直接替换✓ 有现货
$3.6591 / 个
查看数据手册 →TPS7A4701RGWR-Q1
✅ 直接替换📋 参考替代料（不在目录中）
TPS7A4701RGWT
✅ 直接替换📋 参考替代料（不在目录中）
LT3045EDC
✅ 直接替换 ⚠️ 规格未核验📋 参考替代料（不在目录中）
ADM7150ARDZ
✅ 直接替换 ⚠️ 规格未核验📋 参考替代料（不在目录中）
FDA903U 最大额定值与电气特性
| 输出类型 | Adjustable |
| 输出电压范围 | 1.4 V to 34 V |
| 最大输出电流 | 1 A |
| 输入电压范围 | 3 V to 35 V |
| 压差电压 | 200 mV at 1 A |
| 输出噪声 | 4.17 uVrms (20 Hz to 100 kHz) |
| PSRR | 72 dB at 1 kHz |
| 静态电流 | 6.4 mA |
| 热阻 | 31.4 C/W |
| 工作温度 | -40C to +125C |
| 封装 | VQFN-20 (RGW) 5x5 mm |
| 安装类型 | Surface Mount |
| MSL 等级 | 2 (1 year) |
| RoHS 状态 | Compliant |
| 使能引脚 | Yes (active-high) |
FDA903U 引脚配置
| 引脚 1 | OUT — Regulated output voltage |
| 引脚 5 | GND — Ground |
| 引脚 6 | EN — Enable (active high) |
| 引脚 7 | IN — Input supply |
典型应用
FDA903U 适用于 6 应用s: High-End Audio DAC Power Supply, RF Transceiver Power Rail, Precision ADC Reference Buffer, Industrial 24V Bus Power, Test and Measurement Instrumentation, Portable Battery-Powered Devices.
High-End Audio DAC Power Supply
Provides clean 5V rail for audio DACs with 4.17uVrms noise. The FDA903U's ultra-low noise and high PSRR ensure that the power supply does not introduce audible artifacts into the audio signal. In a typical audio DAC application, the FDA903U is placed between the system 5V rail and the DAC's AVDD pin, with a 10uF ceramic capacitor on input and output. Compared to switching regulators, the LDO eliminates switching noise but dissipates more power; for a 12V-to-5V conversion at 500mA, power dissipation is 3.5W, requiring adequate thermal management.
推荐
RF Transceiver Power Rail
Provides clean power to PLL/VCO circuits, minimizing phase noise. The FDA903U's 4.17uVrms noise and 72dB PSRR at 1kHz are critical for RF applications where power supply noise can degrade signal integrity. In a typical RF transceiver, the FDA903U is used to power the PLL charge pump and VCO, with careful layout to minimize parasitic inductance. The high PSRR suppresses ripple from upstream DC-DC converters, ensuring stable frequency synthesis.
推荐
Precision ADC Reference Buffer
Buffers reference voltage for high-resolution ADCs, ensuring accuracy. The FDA903U's low noise and high PSRR are essential for precision measurement systems. In a typical ADC application, the FDA903U provides a clean reference voltage to the ADC's VREF pin, with a low-ESR capacitor on the output. The wide input range allows operation from various supply rails, and the enable pin enables power sequencing in multi-rail systems.
推荐
Industrial 24V Bus Power
Regulates 24V industrial bus down to 5V or 3.3V for control electronics. The FDA903U's 35V input range provides ample headroom for 24V systems, and its low dropout ensures regulation even with voltage dips. In a typical industrial application, the FDA903U is used to power microcontrollers and sensors, with input protection diodes and output capacitors for stability. The thermal shutdown feature protects the device in harsh environments.
推荐
Test and Measurement Instrumentation
Provides clean power for precision instruments, reducing measurement errors. The FDA903U's ultra-low noise and high PSRR are critical for oscilloscopes, multimeters, and spectrum analyzers. In a typical instrument, the FDA903U powers analog front-end circuits, ensuring accurate signal acquisition. The enable pin allows controlled power-up, and the thermal pad aids heat dissipation in compact enclosures.
推荐
Portable Battery-Powered Devices
Regulates battery voltage to low-noise rails for audio and sensor circuits. The FDA903U's low quiescent current (6.4mA) extends battery life, and its low dropout maximizes usable battery voltage. In a typical portable device, the FDA903U powers audio codecs and MEMS sensors, with the enable pin for power saving. The small VQFN-20 package fits space-constrained designs.
推荐
推荐产品汇总
工程参考数据： FDA903U ——对比、设计指导和合规信息。
选型指南
与替代料对比
| 参数 | 本产品 | TPS7A4700RGWR | TPS7A4701RGWR-Q1 | TPS7A3301RGWR |
|---|---|---|---|---|
| Package | VQFN-20 (RGW) | VQFN-20 (RGW) - same | VQFN-20 (RGW) - same | VQFN-20 (RGW) - same |
| Brand | Texas Instruments | Texas Instruments | Texas Instruments | Texas Instruments |
| Output Current | 1 A | 1 A | 1 A | 1 A (negative) |
| Output Voltage Range | 1.4V to 34V | 1.4V to 34V | 1.4V to 34V | -36V to -1.4V |
| Enable Pin | Yes (active-high) | No | Yes (active-high) | Yes (active-high) |
| Automotive Grade | No | No | Yes (AEC-Q100) | No |
| Output Noise | 4.17 uVrms | 4.17 uVrms | 4.17 uVrms | 4.17 uVrms |
| PSRR at 1kHz | 72 dB | 72 dB | 72 dB | 72 dB |
关键差异点
- Only VQFN-20 family member with enable pin （对比 TPS7A4700RGWR)
- Automotive grade option available （对比 TPS7A4701RGWR-Q1)
- Positive voltage polarity （对比 TPS7A3301RGWR)
设计说明
At VIN=12V, VOUT=5V, and 1A load, power dissipation is 7W. The VQFN-20 package has theta_JA of 31.4 C/W, resulting in a 220C junction temperature rise. A heatsink or at least 1 square inch of copper pour is required for reliable operation above 2W dissipation.
Place input and output capacitors as close to the IC pins as possible. Use a 10uF ceramic capacitor on the input and a 10uF ceramic capacitor on the output. Add a 0.1uF ceramic capacitor in parallel for high-frequency noise bypass.
Do not exceed the maximum input voltage of 35V. Ensure the external resistor divider uses 1% or better tolerance resistors to maintain output voltage accuracy. The NR/SS capacitor controls startup time and noise bandwidth - do not omit it.
合规信息
RoHS compliant per TI product page. Not AEC-Q100 qualified - choose TPS7A4701RGWR-Q1 for automotive.
