FDA803Q - 1A, 35V Ultra-Low Noise LDO | Texas Instruments
MPN: FDA803Q ✓ AktifFDA803Q Genel Bakış
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.
Drop-in alternatifler için FDA803Q — aynı paket, pin-başına uyumlu. PCB yeniden montajı gerektiren farklı paket bileşenleri dışlanmıştır.
Bu Serideki Variantlar
Yedek parça uyumlu olan aynı serideki modeller FDA803Q (aynı form faktörü ve ayağa oturma) — farklı olan Enable Pin, Input Voltage Range, MSL Level, Output Type, Output Voltage Range.
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FDA803Q Maksimum Değerlendirmeler & Elektriksel Özellikler
| Çıkış Türü | Adjustable |
| Çıkış Gerilimi Aralığı | 1.4 V to 34 V |
| Maksimum Çıkış Akımı | 1 A |
| Giriş电压范围 | 3 V to 35 V |
| Düşüş电压 | 200 mV at 1 A |
| Çıkış Gürültüsü | 4.17 uVrms (20 Hz to 100 kHz) |
| PSRR | 72 dB at 1 kHz |
| Durağan Akım | 6.4 mA |
| Termal Direnç | 31.4 C/W |
| İşletim Sıcaklığı | -40C to +125C |
| Paket | VQFN-20 (RGW) 5x5 mm |
| Montaj Türü | Surface Mount |
| MSL Seviyesi | 2 (1 year) |
| RoHS Durumu | Compliant |
| Etkin Pin | Yes (active-high) |
FDA803Q Pin Yapısı
| Pin 1 | OUT — Regulated output voltage |
| Pin 5 | GND — Ground |
| Pin 6 | EN — Enable (active high) |
| Pin 7 | IN — Input supply |
| Pin 9 | NR/SS — Noise reduction/soft-start capacitor |
| Pin 10 | FB — Feedback for output voltage setting |
| Pin 13 | GND — Ground |
| Pin 17 | OUT — Regulated output voltage |
| Pin 20 | IN — Input supply |
| Pin 21 | PAD — Exposed thermal pad (connect to GND) |
Tipik Uygulamalar
FDA803Q için uygundur 6 uygulamas: 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.
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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.
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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.
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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.
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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.
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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.
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Önerilen Ürünler Özeti
Mühendislik referans verileri: FDA803Q — karşılaştırma, tasarım rehberi ve uyumluluk bilgileri.
Seçim Kılavuzu
Alternatiflerle Karşılaştırma
| Parametre | Bu Ürün | 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 |
Ana Farklılayıcılar
- Only VQFN-20 family member with enable pin (karşılaştırma:TPS7A4700RGWR)
- Automotive grade option available (karşılaştırma:TPS7A4701RGWR-Q1)
- Positive voltage polarity (karşılaştırma:TPS7A3301RGWR)
Tasarım Notları
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.
Uyumluluk Bilgisi
RoHS compliant per TI product page. Not AEC-Q100 qualified - choose TPS7A4701RGWR-Q1 for automotive.
