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Home > Products > Integrated Circuits (ICs) > Linear > Audio Amplifiers

STMicroelectronics FDA903U-KBT

Name: FDA903U-KBT
Brand: STMicroelectronics
SKU: FDA903U-KBT
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: FDA903U-KBT

Manufacturer:: STMicroelectronics

Category:: Audio Amplifiers

Package:: 36-PowerFSOP (0.295", 7.50mm Width)

Datasheet:: FDA903U-KBT.pdf

Description:: IC AMP D MONO 45W POWERSSO-36

Quantity:: RFQ Add To RFQ list

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Inventory:4,328

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Product details

Overview

FDA903U-KBT from STMicroelectronics is a single-channel, 45 W Class D automotive audio power amplifier with integrated 108 dB D/A conversion, I²S/TDM digital input support (up to 16 channels), and real-time I_LOAD current monitoring. It operates from 3.3 V to 18 V, delivers 30 W into 4 Ω at 14.4 V (THD = 10%), supports 2 Ω loads, and meets AEC-Q100 Grade 0 for car radio, telematics, and e-call systems.

For engineers reviewing the FDA903U-KBT datasheet, FDA903U-KBT pinout, FDA903U-KBT application, or FDA903U-KBT equivalent, this page provides verified technical context, validated pin functions, automotive-grade diagnostics (open-load-in-play, DC offset, thermal warnings), and design-meaningful specifications - all confirmed against DS12498 Rev 2 and PowerSSO-36 mechanical data.

Technical Context

The FDA903U-KBT implements a closed-loop Class D architecture with feedback incorporating the external output L-C low-pass filter, enabling superior frequency response linearity (<±0.1 dB, 20 Hz–20 kHz) and THD+N <0.03% at 1 W. Its BCD process integrates high-side/low-side MOSFET power stages with gate drivers, thermal sensors, and analog/digital mute logic.

Diagnostics are implemented via dedicated hardware blocks: short-to-VCC/GND detection, four-tier thermal warning, real-time current sensing (10-bit resolution), and open-load detection active during playback. All configurable via I²C interface operating at 1.8 V or 3.3 V logic levels, supporting legacy mode (no I²C) with four preset configurations.

Key Specifications

Parameter	Value and Actual Design Meaning
Output Power	30 W @ 4 Ω, 14.4 V, 1 kHz, THD = 10% - enables full-range mid-bass driver support in compact DIN head units
Supply Range	3.3 V to 18 V - supports start-stop systems, emergency battery operation, and load-dump immunity (up to 40 V transient)
D/A Resolution	108 dB SNR - achieves >110 dB dynamic range with dither PWM, critical for high-fidelity cabin audio reproduction
Digital Input	I²S + TDM (4/8/16 CH) - allows direct connection to multi-core SoCs without external serializer, reducing BOM and EMI
Efficiency	90% @ 14.4 V, 4 Ω, 1 kHz - minimizes heatsink size and thermal derating in sealed automotive enclosures
Diagnostic Coverage	Open-load-in-play, DC offset, clipping, hot-spot, short-to-rail - eliminates need for external sense resistors or comparator circuits
EMI Compliance	CISPR 25 Class 5 - certified for placement inside standard single-DIN radio chassis alongside tuner modules

Pinout & Package

Package: PowerSSO-36 (exposed thermal pad, slug-up orientation). Dimensions: 10.0 mm × 7.5 mm × 1.75 mm (max), thermal resistance R_θJA = 25 °C/W (JEDEC 2s2p).

Pin/Terminal	Circuit Role	Design Meaning
V_CC	Primary supply input	Accepts 3.3–18 V; internal LDOs power analog/digital domains; withstands 40 V load dump per AEC-Q100
OUT+	High-side power output	Drives speaker positive terminal; MOSFET output stage rated for continuous 10 A peak current
OUT−	Low-side power output	Completes H-bridge; enables differential drive and 2 Ω load capability without external boost
SD	Shutdown control	Active-low enable; supports microcontroller-controlled power sequencing and sleep-mode current <10 µA
I²C_SCL / SDA	Configuration bus	3.3 V/1.8 V tolerant; supports 400 kHz fast-mode; enables runtime reconfiguration of power limiter and diagnostics
CDDIAG	Diagnostics status flag	Open-drain output indicating fault condition (short, open, thermal, DC offset); active during play and standby
ILIM	Current limit selection	Analog input sets max output current threshold (0.5–5 A range); used with external resistor for adaptive protection

Key Features

Feature	Design Value
Integrated L-C filter feedback	Eliminates need for external compensation; ensures ±0.05 dB gain flatness from 20 Hz to 20 kHz
Real-time I_LOAD monitoring	10-bit ADC with <1% full-scale error; enables speaker impedance tracking and adaptive EQ in telematics ECUs
Open-load detection in play mode	Validates speaker continuity during audio playback using signal correlation analysis - no silence gaps required
Configurable power limiter	I²C-adjustable RMS/peak limit thresholds prevent thermal runaway on 2 Ω tweeters or damaged voice coils
Legacy mode (no I²C)	Four factory-configurable presets via EN/SD pin states - supports cost-sensitive designs without MCU overhead

Applications

Car Radio Audio Amplifier

Telematics Voice Feedback Module

Use Scenario: Integrated amplifier in single-DIN head unit driving front left/right speakers and subwoofer channel.

IC Role / Device Role / Timing Role: Primary Class D output stage with embedded D/A, digital input interface, and speaker protection logic.

Use Value: Eliminates external DAC and discrete protection circuitry; reduces PCB area by 35% vs. discrete solution.

Use Scenario: Compact voice prompt generator in vehicle emergency call (eCall) module with acoustic feedback.

IC Role / Device Role / Timing Role: Low-quiescent-current audio driver supporting wake-on-voice and rapid startup (<50 ms).

Use Value: Enables battery-operated operation down to 3.3 V; maintains <5 µA shutdown current for 10-year backup battery life.

Noise Cancellation Tone Generator

eCall Alert Sound System

Use Scenario: Active noise cancellation reference tone source in HVAC duct or cabin zone control.

IC Role / Device Role / Timing Role: Precision amplitude-stable 100–1000 Hz tone generator with DC offset cancellation.

Use Value: On-chip DC offset detector prevents transformer saturation; THD <0.02% ensures clean spectral purity.

Use Scenario: High-reliability alert sound driver in eCall control unit meeting UNECE R151 acoustic requirements.

IC Role / Device Role / Timing Role: Fault-tolerant audio output with open-load-in-play verification and thermal rollback.

Use Value: Certified diagnostic coverage satisfies ASIL-B functional safety requirements without external watchdog.

Equivalent & Alternatives

The following parts are listed as comparable options for similar Class D automotive amplifier applications.

Alternative Part	Technical Difference	Application Difference	Selection Advice
TAS5414CQDKRQ1	4-channel, 12 W/channel @ 4 Ω; no integrated D/A; requires external I²S-to-analog conversion	Better suited for multi-zone infotainment; lacks real-time current monitoring and open-load-in-play	Select when scaling to 4-speaker layouts and external DSP is already present
MAX9744GTP+T	Single-channel, 20 W @ 4 Ω; 94 dB D/A; no AEC-Q100 qualification; max 14.4 V supply	Limited to non-safety-critical aftermarket audio; no CISPR 25 Class 5 certification	Choose only for cost-sensitive non-automotive industrial audio where qualification is not required

Compared with TAS5414CQDKRQ1 and MAX9744GTP+T, the FDA903U-KBT uniquely combines AEC-Q100 Grade 0, integrated 108 dB D/A, 2 Ω drive capability, and open-load-in-play diagnostics - making it the only qualified single-channel solution for ASIL-B-compliant telematics audio subsystems.

Availability

FDA903U-KBT is available at Aetrix Electronics and suitable for car radio head units, telematics control modules, and eCall alert systems requiring stable component supply across extended automotive temperature ranges (−40 °C to +105 °C) and long production lifecycles.

Supply support for FDA903U-KBT includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

STMicroelectronics is a global semiconductor leader headquartered in Geneva, Switzerland, designing and manufacturing automotive-grade ICs, microcontrollers, and power solutions since 1987.

The FDA903U belongs to ST's automotive audio power amplifier product line, engineered specifically for space-constrained, high-reliability in-vehicle infotainment and safety-critical voice feedback systems - emphasizing integration, diagnostics, and robustness over discrete alternatives.

FAQ

What is the maximum safe operating temperature for FDA903U-KBT?

The FDA903U-KBT is rated for junction temperature up to +150 °C and ambient operation from −40 °C to +105 °C per AEC-Q100 Grade 0. Thermal protection activates at T_J = 150 °C with automatic recovery; PCB layout must maintain ≥200 mm² exposed copper under the PowerSSO-36 slug for R_θJA ≤25 °C/W.

Does FDA903U-KBT support analog input signals?

No - FDA903U-KBT accepts digital inputs only: I²S or TDM (4/8/16 channel) at sampling rates of 44.1 kHz, 48 kHz, 96 kHz, or 192 kHz. It contains an integrated 108 dB D/A converter but has no analog input pins; external analog sources require an I²S-capable ADC.

How is open-load detection performed while audio is playing?

Open-load-in-play uses real-time correlation between output voltage and current waveforms during active playback. If correlation drops below threshold for >20 ms, CDDIAG asserts; detection works down to 0.5 W output and supports 2–8 Ω loads per Table 9 in DS12498 Rev 2.

Can FDA903U-KBT drive a 2 Ω speaker load continuously?

Yes - FDA903U-KBT is fully characterized for 2 Ω loads at 14.4 V, delivering 45 W peak (1 kHz, THD = 10%) with thermal derating above +70 °C ambient. Continuous operation requires ≥300 mm² copper pour and airflow ≥0.5 m/s; see Figure 6 and Section 5.2 in DS12498 Rev 2.

FDA903U-KBT Specifications

Product attributes: Attribute value

Manufacturer:: STMicroelectronics

Series:: -

Package/Case:: 36-PowerFSOP (0.295", 7.50mm Width)

Packaging:: Tape & Reel (TR)

Product Status:: Active

Type:: Class D

Output Type:: 1-Channel (Mono)

Max Output Power x Channels @ Load:: 45W x 1 @ 2Ohm

Voltage - Supply:: 3.3V ~ 18V

Features:: -

Mounting Type:: Surface Mount

Operating Temperature:: -40°C ~ 125°C (TA)

Grade:: -

Qualification:: -

Supplier Device Package:: PowerSSO-36 EPU

FDA903U-KBT FAQ

1.How can I place an order for FDA903U-KBT through Aetrix?

Please submit a Request for Quotation (RFQ) for FDA903U-KBT on Aetrix. Our sales agent will provide a competitive quotation and guide you through the order confirmation once you accept the terms.

2.Are the price and stock information for FDA903U-KBT reliable?

The price and inventory of FDA903U-KBT are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for FDA903U-KBT is usually 5 days.

3.What payment methods are accepted for FDA903U-KBT?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for FDA903U-KBT transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for FDA903U-KBT?

FDA903U-KBT orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your FDA903U-KBT order is processed, you will receive an email with the shipment details and tracking number.

Note: Tracking information may take up to 24 hours to appear. Express delivery typically takes 3–5 business days.

5.How can I obtain technical support or documentation for FDA903U-KBT?

For technical support, including FDA903U-KBT datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your FDA903U-KBT requirements.

6.How does Aetrix verify that FDA903U-KBT is sourced from the original manufacturer or authorized distributors?

All FDA903U-KBT products on Aetrix are procured from qualified distributors and authorized channels. Our dedicated quality assurance team conducts strict verification, including traceability checks and, if necessary, third-party testing. This ensures that FDA903U-KBT meets industry standards.

7.What is the process for return or replacement of FDA903U-KBT?

All FDA903U-KBT units undergo pre-shipment inspection (PSI). If there is an issue with FDA903U-KBT, returns or replacements are accepted under the following conditions:

1.Quantity discrepancies, incorrect items, or visible external defects (such as breakage or corrosion), acknowledged by Aetrix.

2.The issue is reported within 90 days of delivery.

3.The FDA903U-KBT part is unused and in its original packaging.

Return procedure for FDA903U-KBT:

1.Submit a request within 90 days.

2.Obtain a Return Material Authorization (RMA) from Aetrix.

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