FDA803Q - 1A, 35V Ultra-Low Noise LDO | Texas Instruments
MPN： FDA803Q ✓ 啟用中FDA803Q 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 operates by dissipating excess power as heat, providing a clean, low-noise output. LDOs are essential in power management ICs, serving as the final stage in a power supply chain to filter out ripple and noise from switching regulators. The FDA803Q fits into the hierarchy: LDO -> linear regulator -> voltage regulator -> power management IC -> semiconductor.
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 FDA803Q 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 FDA803Q — 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： FDA803Q （相同外形與佔位） — 差異在於 Enable Pin, Input Voltage Range, MSL Level, Output Type, Output Voltage Range.
TPS7A4700RGWR
✅ 直接替換聯絡詢價
查看資料表 →TPS7A4701RGWR-Q1
✅ 直接替換📋 參考替代品（不在目錄中）
TPS7A4701RGWT
✅ 直接替換📋 參考替代品（不在目錄中）
LT3045EDC
✅ 直接替換 ⚠️ 規格未經驗證📋 參考替代品（不在目錄中）
ADM7150ARDZ
✅ 直接替換 ⚠️ 規格未經驗證📋 參考替代品（不在目錄中）
FDA803Q 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) |
FDA803Q 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 9 | NR/SS — Noise reduction/soft-start capacitor |
| 腳位 10 | FB — Feedback for output voltage setting |
| 腳位 13 | GND — Ground |
| 腳位 17 | OUT — Regulated output voltage |
| 腳位 20 | IN — Input supply |
| 腳位 21 | PAD — Exposed thermal pad (connect to GND) |
典型應用
FDA803Q 適用於 6 應用s: High-End Audio DAC Power Supply, RF Transceiver Power Supply, Precision ADC Reference Buffer, Industrial 24V Bus Power, Test and Measurement Instrumentation, Portable Medical Devices.
High-End Audio DAC Power Supply
Provides clean 5V rail for audio DACs with 4.17uVrms noise. The FDA803Q'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 FDA803Q 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.
推薦
RF Transceiver Power Supply
Powers PLL/VCO circuits with 72dB PSRR at 1kHz, minimizing phase noise. The FDA803Q's high PSRR suppresses ripple from upstream switching regulators, which is critical for RF signal integrity. In an RF transceiver, the FDA803Q is used to power the VCO and PLL, with a 0.1uF capacitor close to the VCC pin to filter high-frequency noise. The low noise floor of 4.17uVrms ensures that the power supply does not contribute to phase noise, improving overall system performance.
推薦
Precision ADC Reference Buffer
Buffers reference voltage for 24-bit ADCs with 4.17uVrms noise. The FDA803Q's low noise and high accuracy make it ideal for driving the reference input of precision ADCs. In a data acquisition system, the FDA803Q is used to generate a clean 5V reference from a noisy 12V rail, with a 10uF capacitor on the output to stabilize the reference. The low dropout voltage of 200mV ensures that the reference remains regulated even with input voltage variations.
推薦
Industrial 24V Bus Power
Regulates 24V industrial bus to 5V for sensors and microcontrollers. The FDA803Q's wide input range of up to 35V makes it suitable for industrial applications where the supply voltage can vary. In a factory automation system, the FDA803Q is used to power a microcontroller and sensors from a 24V bus, with a 10uF input capacitor to handle transients. The thermal shutdown protection ensures safe operation in harsh environments.
推薦
Test and Measurement Instrumentation
Provides clean power for oscilloscopes and signal generators. The FDA803Q's low noise and high PSRR are essential for maintaining measurement accuracy. In a benchtop instrument, the FDA803Q is used to power analog front-end circuits, with a 10uF output capacitor to reduce noise. The enable pin allows for power sequencing in multi-rail systems, ensuring that sensitive analog circuits power up after digital circuits.
推薦
Portable Medical Devices
Powers low-noise analog front-ends in portable monitors. The FDA803Q's low quiescent current of 6.4mA extends battery life in portable devices. In a portable ECG monitor, the FDA803Q is used to power the analog front-end, with a 10uF output capacitor to filter noise. The small VQFN-20 package saves board space, and the wide input range accommodates battery voltage variations.
推薦
推薦產品摘要
工程參考資料，適用於 FDA803Q — 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 | 3.8 uVrms |
| PSRR at 1kHz | 72 dB | 72 dB | 72 dB | 75 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.
