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

STMicroelectronics TDA7851FH-QIX

Name: TDA7851FH-QIX
Brand: STMicroelectronics
SKU: TDA7851FH-QIX
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: TDA7851FH-QIX

Manufacturer:: STMicroelectronics

Category:: Audio Amplifiers

Package:: 25-Flexiwatt, Formed Leads

Datasheet:: TDA7851FH-QIX.pdf

Description:: IC AMP AB QUAD 75W 25FLEXIWATT

Quantity:: RFQ Add To RFQ list

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Inventory:3,879

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Product details

Overview

TDA7851FH-QIX from STMicroelectronics is a 4-channel Class AB MOSFET audio power amplifier delivering up to 48 W per channel into 4 Ω and 72 W per channel into 2 Ω, with fixed 26 dB gain, integrated standby/mute/automute functions, and rail-to-rail output swing for automotive head unit applications.

For engineers reviewing the TDA7851FH-QIX datasheet, TDA7851FH-QIX pinout, TDA7851FH-QIX application, or TDA7851FH-QIX equivalent, this device is selected for high-fidelity car audio systems requiring robust 2 Ω drive capability, low THD (0.01% typ.), A-weighted output noise ≤50 μV, and comprehensive protection including short-circuit, thermal, load dump, and reversed-battery tolerance.

Technical Context

The TDA7851FH-QIX employs Multipower BCD technology with fully complementary P-Channel/N-Channel MOSFET output stages enabling rail-to-rail voltage swing and minimized saturation losses. Its internal fixed-gain architecture eliminates external compensation and bootstrap capacitors, reducing BOM count while maintaining Hi-Fi distortion performance (THD ≤0.05% at 4 W).

It integrates real-time protection logic: output DC offset detection (±1–3 V threshold), automute activation at VS ≤7.5 V, and soft thermal limiting triggered above 150 °C junction temperature. The device operates across 8–18 V supply range with quiescent current of 100–300 mA and supports CMOS-compatible standby/mute control with defined threshold voltages (1.2 V OFF / 2.6 V ON).

Key Specifications

Parameter	Value and Actual Design Meaning
Output Power	4 × 48 W @ 4 Ω, 10% THD; 4 × 72 W @ 2 Ω, max - enables high-SPL speaker drive without external boost stages
THD+N	0.01% typ. @ 4 W, 4 Ω - meets Hi-Fi audio fidelity requirements for OEM car radio front-end amplification
Voltage Gain	26 dB fixed (25–27 dB range) - eliminates need for external gain-setting resistors and reduces layout sensitivity
Supply Range	8–18 V DC - compatible with automotive battery transients (up to 28 V DC, 50 V pk/50 ms)
Output Noise	35–100 μV A-weighted (20 Hz–20 kHz) - ensures clean signal path without audible hiss in quiet cabin environments
Thermal Resistance	R_{th j-case} = 1 °C/W - allows direct heatsink mounting with minimal thermal interface resistance for stable 85 W dissipation
Protections	Short-circuit (to GND/V_S/load), inductive load, thermal limiter, load dump (50 V), reversed battery, ESD - enables unattended operation in harsh vehicle electrical environments

Pinout & Package

Package: Flexiwatt25 (horizontal), 25-pin single-in-line (SIL) package with exposed thermal pad; designed for vertical PCB mounting with heatsink contact on top surface.

Pin/Terminal	Circuit Role	Design Meaning
1, 2, 3, 4	Channel 1–4 Inputs	Differential-capable, ±8 Vpk tolerant inputs; no AC coupling required for ground-referenced sources
5	Standby Control	CMOS-compatible input; <1.2 V = standby (μA leakage), >2.6 V = active; controls global amplifier enable
6, 7, 8, 9	Channel 1–4 Outputs	MOSFET bridge outputs; rail-to-rail swing supports full dynamic range into 2 Ω loads
10	GND	Power ground reference; separate from signal ground to minimize noise coupling
11	V_S	Main 8–18 V supply input; decoupling capacitor required per application circuit (Fig. 2)
12	Mute Control	CMOS-compatible input; <1.2 V = mute (≥80 dB attenuation), >2.6 V = play; independent of standby state
13–16	Channel 1–4 Feedback	Internal feedback nodes; no external connection - gain is factory-fixed at 26 dB
17–20	Channel 1–4 AC-GND	AC ground pins for input stage biasing; require 0.1 μF capacitors to chassis ground for pop suppression
21	Offset Detector Output	Open-collector flag indicating output DC offset >±1 V; used for speaker protection monitoring
22	SVR Capacitor	Connects to 10 μF minimum capacitor; governs turn-on/off timing and suppresses power-on/off transients
23	Muting Pin Current Sense	Current-sense node for mute logic; ±1 μA max leakage ensures reliable CMOS-level detection
24, 25	Heatsink Pad / Thermal Tab	Electrically isolated thermal interface; must be connected to heatsink for R_{th j-case} = 1 °C/W performance

Key Features

Feature	Design Value
Rail-to-rail MOSFET output stage	Enables full supply voltage utilization across 2–4 Ω loads, maximizing output power without rail boosting
Integrated automute at low V_S	Automatically mutes amplifier when supply drops below 7.5 V, preventing distortion during cranking or brownout
No external compensation or bootstrap caps	Reduces bill-of-materials by 4–6 passive components per channel and eliminates stability tuning effort
Output DC offset detector	Provides fail-safe flag for speaker protection; triggers at ±1 V differential offset before damage occurs
Load dump and reversed-battery tolerance	Withstands 50 V transient spikes (50 ms) and −18 V reverse polarity - eliminates need for external TVS or diode protection

Applications

Automotive Head Unit Amplifier

Aftermarket Car Stereo System

Use Scenario: Integrated 4-channel amplifier in OEM infotainment head unit driving front/rear speakers and subwoofer outputs.

IC Role / Device Role / Timing Role: Primary Class AB power stage delivering full-range audio with <0.05% THD at rated power.

Use Value: Eliminates need for discrete MOSFET H-bridges and external protection ICs, reducing board area by ~35% versus discrete solutions.

Use Scenario: Compact 4×48 W amplifier module in plug-and-play aftermarket stereo replacement units.

IC Role / Device Role / Timing Role: Self-contained audio power IC with built-in muting, standby, and automute for seamless integration with microcontroller UI.

Use Value: Enables single-IC solution for 4-channel output with no gain-setting or compensation design effort - time-to-market reduction ≥4 weeks.

High-Power 2 Ω Speaker Driver

Thermally Constrained Dashboard Audio Module

Use Scenario: Driving low-impedance component speakers (2 Ω nominal) in premium vehicle audio systems.

IC Role / Device Role / Timing Role: High-current MOSFET output stage delivering 72 W/channel into 2 Ω with soft thermal limiting.

Use Value: Sustains 26 W continuous dissipation under real music program (Figure 16) without thermal shutdown - validated for 70 °C ambient.

Use Scenario: Space-constrained dashboard-mounted amplifier feeding tweeters and midranges in compact EV infotainment systems.

IC Role / Device Role / Timing Role: Low-noise (≤50 μV), low-standby-current (≤20 μA) amplifier with integrated SVR capacitor timing for pop-free startup.

Use Value: Achieves <−100 dBV crosstalk and 70 dB SVR without external filtering - meets OEM EMC requirements without added ferrites or shields.

Equivalent & Alternatives

The following parts are listed as comparable options for similar 4-channel automotive audio amplifier applications.

Alternative Part	Technical Difference	Application Difference	Selection Advice
TDA7850F	Same pinout, lower max power (4×35 W/4 Ω), no automute function, higher THD (0.08% typ.)	Lacks supply-voltage-dependent mute; unsuitable for cranking-sensitive systems	Select when cost is prioritized over cranking immunity and peak power headroom
TDA7388	4×41 W/4 Ω, BCD process (not MOSFET), R_{th j-case} = 1.5 °C/W, no offset detector	Higher thermal resistance requires larger heatsink; no DC fault monitoring capability	Select when legacy BCD compatibility is required and 2 Ω drive is not needed

Compared with TDA7851FH-QIX, TDA7850F trades automute and 13 W/channel peak power for lower cost, while TDA7388 offers proven reliability in mature designs but lacks rail-to-rail swing and integrated protection features critical for modern 2 Ω speaker systems.

Availability

TDA7851FH-QIX is available at Aetrix Electronics and suitable for automotive infotainment systems, premium aftermarket stereo modules, and thermally constrained dashboard audio subsystems requiring stable component supply and long-term production continuity.

Supply support for TDA7851FH-QIX 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 analog, MCU, power, and automotive ICs for industrial and consumer applications.

The TDA7851FH-QIX belongs to ST's automotive audio power amplifier product line, engineered specifically for high-efficiency, high-fidelity car radio systems demanding robustness against automotive electrical stressors and minimal external component count.

FAQ

What is the maximum safe operating supply voltage for TDA7851FH-QIX?

The absolute maximum DC supply voltage is 28 V, and peak supply voltage is rated at 50 V for durations up to 50 ms - sufficient to withstand automotive load dump events per ISO 7637-2 Pulse 5a. Continuous operation above 18 V is not recommended and may trigger overvoltage protection or degrade long-term reliability.

Does TDA7851FH-QIX require external gain-setting resistors?

No. The TDA7851FH-QIX features internally fixed voltage gain of 26 dB (25–27 dB range), eliminating the need for external gain-setting resistors or compensation networks. This simplifies layout, improves channel matching, and removes gain drift due to resistor tolerance or temperature variation.

How does the automute function respond to low battery voltage?

The automute function activates when supply voltage falls below 7.0–7.5 V (typical threshold), attenuating output by ≥80 dB to prevent distorted audio during engine cranking. It deactivates automatically when V_S rises above 8.0 V, ensuring silent re-engagement without user intervention.

Can TDA7851FH-QIX drive 2 Ω speakers continuously?

Yes. The device delivers up to 72 W per channel into 2 Ω loads with excellent thermal margin: at 14.4 V supply and real-world audio program signals, simulated dissipation is 26 W (Figure 17), well within its 85 W total power limit and supported by R_{th j-case} = 1 °C/W when properly heatsinked.

TDA7851FH-QIX Specifications

Product attributes: Attribute value

Manufacturer:: STMicroelectronics

Series:: -

Package/Case:: 25-Flexiwatt, Formed Leads

Packaging:: Tube

Product Status:: Active

Type:: Class AB

Output Type:: 4-Channel (Quad)

Max Output Power x Channels @ Load:: 75W x 4 @ 2Ohm

Voltage - Supply:: 8V ~ 18V

Features:: Mute, Short-Circuit and Thermal Protection, Standby

Mounting Type:: Through Hole

Operating Temperature:: 150°C (TJ)

Grade:: -

Qualification:: -

Supplier Device Package:: 25-Flexiwatt (Horizontal)

TDA7851FH-QIX FAQ

1.How can I place an order for TDA7851FH-QIX through Aetrix?

Please submit a Request for Quotation (RFQ) for TDA7851FH-QIX 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 TDA7851FH-QIX reliable?

The price and inventory of TDA7851FH-QIX are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for TDA7851FH-QIX is usually 5 days.

3.What payment methods are accepted for TDA7851FH-QIX?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for TDA7851FH-QIX transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for TDA7851FH-QIX?

TDA7851FH-QIX orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your TDA7851FH-QIX 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 TDA7851FH-QIX?

For technical support, including TDA7851FH-QIX datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your TDA7851FH-QIX requirements.

6.How does Aetrix verify that TDA7851FH-QIX is sourced from the original manufacturer or authorized distributors?

All TDA7851FH-QIX 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 TDA7851FH-QIX meets industry standards.

7.What is the process for return or replacement of TDA7851FH-QIX?

All TDA7851FH-QIX units undergo pre-shipment inspection (PSI). If there is an issue with TDA7851FH-QIX, 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 TDA7851FH-QIX part is unused and in its original packaging.

Return procedure for TDA7851FH-QIX:

1.Submit a request within 90 days.

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

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