FDA903D - 1A, 35V Ultra-Low Noise LDO | Texas Instruments
MPN： FDA903D ✓ 啟用中FDA903D 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 subclass of linear regulators, which in turn are a type of voltage regulator within the broader power management IC (PMIC) category. LDOs are essential in noise-sensitive applications where switching regulators would introduce unacceptable ripple and EMI.
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 FDA903D 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 FDA903D — 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。
TPS7A4701RGWR
聯絡詢價
查看資料表 →TPS7A4700RGWR
聯絡詢價
查看資料表 →TPS7A4701RGWR-Q1
📋 參考替代品（不在目錄中）
LT3045EDC
📋 參考替代品（不在目錄中）
ADM7150ARDZ
📋 參考替代品（不在目錄中）
FDA903D 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) |
FDA903D 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 |
| 腳位 10 | NR/SS — Noise reduction/soft-start capacitor |
| 腳位 20 | PAD — Exposed thermal pad (connect to GND) |
典型應用
FDA903D 適用於 6 應用s: High-End Audio DAC Power Supply, RF Transceiver Power Rail, Precision ADC/DAC Reference, Industrial Sensor Interface, Battery-Powered Portable Device, Test and Measurement Instrumentation.
High-End Audio DAC Power Supply
Provides clean 5V rail for audio DACs with 4.17uVrms noise. The FDA903D'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 FDA903D 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.
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RF Transceiver Power Rail
The FDA903D provides a clean supply for PLL/VCO circuits, minimizing phase noise. Its 72 dB PSRR at 1 kHz and 4.17 uVrms noise are critical for maintaining signal integrity in RF transceivers. In a typical RF application, the FDA903D is used to power the VCO and PLL, with careful layout to minimize parasitic inductance. The low dropout voltage ensures stable operation even when the input rail is close to the output voltage, which is common in battery-powered RF devices.
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Precision ADC/DAC Reference
The FDA903D buffers reference voltages for high-resolution ADCs and DACs, ensuring accuracy. Its low noise and high PSRR prevent power supply variations from affecting conversion results. In a precision data acquisition system, the FDA903D is used to generate a clean 5V reference from a noisy digital rail. The enable pin allows the reference to be powered down during standby, saving power. The thermal shutdown protection ensures safe operation in harsh environments.
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Industrial Sensor Interface
The FDA903D powers sensor signal conditioning circuits, providing a stable supply for op-amps and ADCs. Its wide input range (3V to 35V) makes it suitable for industrial 24V bus systems. In a typical industrial sensor interface, the FDA903D regulates the 24V bus down to 5V for the analog front end, with a 10uF capacitor on the output to handle transient loads. The low quiescent current (6.4 mA) is beneficial for power-sensitive loop-powered transmitters.
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Battery-Powered Portable Device
The FDA903D provides a low-noise supply for portable audio and instrumentation, extending battery life with its low quiescent current. In a portable device, the FDA903D regulates the battery voltage (e.g., 3.7V Li-ion) down to 3.3V for the analog section, with a dropout of only 200 mV at 1A, maximizing usable battery range. The enable pin allows the regulator to be shut down when the device is in standby, reducing power consumption to near zero.
推薦
Test and Measurement Instrumentation
The FDA903D ensures clean power for precision measurement circuits, reducing measurement errors. Its ultra-low noise and high PSRR are essential for bench-top instruments like multimeters and oscilloscopes. In a typical instrument, the FDA903D is used to power the analog front end, with multiple LDOs for different voltage rails. The thermal shutdown protection prevents damage during prolonged operation at high ambient temperatures.
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推薦產品摘要
工程參考資料，適用於 FDA903D — 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 | TPS7A4701RGWR | TPS7A4700RGWR | TPS7A4701RGWR-Q1 | LT3045EDC | ADM7150ARDZ |
|---|---|---|---|---|---|---|
| Package | VQFN-20 (RGW) | VQFN-20 (RGW) - same | VQFN-20 (RGW) - same | VQFN-20 (RGW) - same | VQFN-20 (RGW) - same | VQFN-20 (RGW) - same |
| Brand | Texas Instruments | Texas Instruments | Texas Instruments | Texas Instruments | Analog Devices | Analog Devices |
| Output Current | 1 A | 1 A | 1 A | 1 A | 0.5 A | 0.6 A |
| Output Voltage Range | 1.4V to 34V | 1.4V to 34V | 1.4V to 34V | 1.4V to 34V | 0V to 15V | 1.2V to 5V |
| Enable Pin | Yes (active-high) | Yes (active-high) | No | Yes (active-high) | Yes (active-high) | Yes (active-high) |
| Automotive Grade | No | No | No | Yes (AEC-Q100) | No | No |
| Output Noise | 4.17 uVrms | 4.17 uVrms | 4.17 uVrms | 4.17 uVrms | 0.8 uVrms | 1.6 uVrms |
| PSRR at 1 kHz | 72 dB | 72 dB | 72 dB | 72 dB | 79 dB | 94 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)
- Higher output current than cross-brand alternatives (對比LT3045EDC)
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.
