FDA903Q - 1A, 35V Ultra-Low Noise LDO | Texas Instruments
MPN： FDA903Q ✓ 啟用中FDA903Q 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 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 FDA903Q 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.
直接替換替代品，適用於 FDA903Q — 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。
此系列的變體
與下列產品可直接替換的同系列型號： FDA903Q （相同外形與佔位） — 差異在於 Enable Pin, Input Voltage Range, MSL Level, Output Type, Output Voltage Range.
TPS7A4700RGWR
✅ 直接替換✗ 缺貨
$3.6591 / 單位
查看資料表 →TPS7A4701RGWR-Q1
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✅ 直接替換 ⚠️ 規格未經驗證📋 參考替代品（不在目錄中）
FDA903Q 最大額定值與電氣特性
| 輸出類型 | Adjustable |
| 輸出電壓範圍 | 1.4 V to 34 V |
| 最大輸出電流 | 1 A |
| 輸入電壓範圍 | 3 V to 35 V |
| 壓降電壓 | 200 mV at 1 A |
| 輸出雜訊 | 4.17 uVrms (20 Hz to 100 kHz) |
| PSRR | 72 dB at 1 kHz |
| 靜態電流 | 6.4 mA |
| 熱阻 | 31.4 C/W |
| 工作溫度 | -40C to +125C |
| 封裝 | VQFN-20 (RGW) 5x5 mm |
| 安裝類型 | Surface Mount |
| MSL 等級 | 2 (1 year) |
| RoHS 狀態 | Compliant |
| 致能腳位 | Yes (active-high) |
FDA903Q 腳位配置
| 腳位 1 | OUT — Regulated output voltage |
| 腳位 5 | GND — Ground |
| 腳位 6 | EN — Enable (active high) |
| 腳位 7 | IN — Input supply |
典型應用
FDA903Q 適用於 6 應用s: High-End Audio DAC Power Supply, RF Transceiver Power Supply, Precision ADC/DAC Reference, Industrial Sensor Interface, Test and Measurement Equipment, Portable Medical Devices.
High-End Audio DAC Power Supply
Provides clean 5V rail for audio DACs with 4.17uVrms noise. The FDA903Q's ultra-low noise and high PSRR ensure that the audio signal path is free from power supply induced artifacts. In a typical audio DAC application, the FDA903Q is placed between the system 5V rail and the DAC's AVDD pin, with a 10uF ceramic capacitor on input and output. This configuration minimizes voltage ripple and noise, preserving the dynamic range and signal-to-noise ratio of the DAC. 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.
推薦
RF Transceiver Power Supply
Powers PLL/VCO circuits with 4.17uVrms noise and 72dB PSRR. The FDA903Q provides a clean, stable voltage to RF components, reducing phase noise and spurious emissions. In an RF transceiver, the FDA903Q is used to supply the VCO and PLL, with careful layout to minimize parasitic inductance. The high PSRR at 1kHz is particularly beneficial for rejecting low-frequency noise from DC-DC converters. The enable pin allows sequenced power-up, preventing latch-up in mixed-signal systems. For a 3.3V rail from a 5V input, the dropout voltage of 200mV ensures regulation even under load transients.
推薦
Precision ADC/DAC Reference
Buffers reference voltages for 16-bit+ ADCs/DACs. The FDA903Q's low noise and high accuracy make it ideal for reference buffering. In a precision data acquisition system, the FDA903Q is used to generate a clean 5V reference from a noisy 12V rail. The output noise of 4.17uVrms ensures that the reference voltage does not introduce errors in the conversion process. The wide input range allows operation from various supply rails, and the enable pin can be used to power down the reference during standby. The thermal shutdown feature protects the device in case of overload.
推薦
Industrial Sensor Interface
Provides clean power for sensor signal conditioning. The FDA903Q is used in industrial sensor interfaces to power op-amps and ADCs, ensuring accurate measurements. In a pressure sensor interface, the FDA903Q regulates a 5V rail from a 24V industrial bus, with a 10uF output capacitor for stability. The low dropout voltage allows operation even when the input voltage is close to the output, maximizing efficiency. The wide input range (up to 35V) makes it suitable for harsh industrial environments. The enable pin can be used for power sequencing in multi-channel systems.
推薦
Test and Measurement Equipment
Supplies low-noise rails for oscilloscopes and signal generators. The FDA903Q's ultra-low noise and high PSRR are critical for maintaining signal integrity in test equipment. In a digital oscilloscope, the FDA903Q powers the analog front-end, ensuring that the noise floor is not degraded. The device's thermal shutdown and current limiting provide protection in case of faults. The enable pin allows remote power control, which is useful in automated test systems. The VQFN-20 package is compact, saving board space in dense designs.
推薦
Portable Medical Devices
Powers sensitive analog circuits in battery-operated devices. The FDA903Q's low quiescent current (6.4mA) and low dropout voltage extend battery life. In a portable ECG monitor, the FDA903Q regulates a 3.3V rail from a 3.7V Li-ion battery, with a 10uF output capacitor. The low noise ensures that the ECG signal is not corrupted by power supply noise. The enable pin can be used to power down unused sections, saving power. The small VQFN-20 package is ideal for space-constrained designs.
推薦
推薦產品摘要
工程參考資料，適用於 FDA903Q — 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 | 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 |
主要差異化特點
- Only VQFN-20 family member with enable pin (對比TPS7A4700RGWR)
- Automotive grade option available (對比TPS7A4701RGWR-Q1)
- Positive voltage polarity (對比TPS7A3301RGWR)
設計說明
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.
合規資訊
RoHS compliant per TI product page. Not AEC-Q100 qualified - choose TPS7A4701RGWR-Q1 for automotive.
