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

STMicroelectronics TDA7851L

Name: TDA7851L
Brand: STMicroelectronics
SKU: TDA7851L
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: TDA7851L

Manufacturer:: STMicroelectronics

Category:: Audio Amplifiers

Package:: 25-Flexiwatt, Formed Leads

Datasheet:: TDA7851L.pdf

Description:: IC AMP AB QUAD 75W 25FLEXIWATT

Quantity:: RFQ Add To RFQ list

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Inventory:1,550

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Product details

Overview

TDA7851L from STMicroelectronics is a quad-channel Class AB MOSFET audio power amplifier in Flexiwatt25 package, designed for high-power automotive head units. It delivers 4 × 48 W into 4 Ω (max), supports 2 Ω loads, features fixed 26 dB gain, internal thermal limiting, and automute at 6.7–7.5 V supply detection - deployed in OEM car radios requiring robust rail-to-rail output swing and low THD (0.01% typ. at 4 W).

For engineers reviewing the TDA7851L datasheet, TDA7851L pinout, TDA7851L application, or TDA7851L equivalent, key selection criteria include 2 Ω drive capability, integrated standby/mute logic, absence of external bootstrap capacitors, and thermal protection behavior under sustained 70 °C ambient conditions.

Technical Context

The TDA7851L uses Multipower BCD technology with fully complementary P-Channel/N-Channel MOSFET output stage, enabling rail-to-rail voltage swing and minimizing saturation losses. Its architecture integrates fixed-gain amplification (26 dB), internal compensation, and CMOS-compatible control pins for standby and mute functions.

It implements automute triggered by supply voltage drop below 6.7–7.5 V, protects against output short circuits (to GND, VS, across load), inductive load transients, load dump (50 V peak), reversed battery, and ESD. Thermal management employs a soft limiter with junction temperature limit of 150 °C and junction-to-case thermal resistance ≤1 °C/W.

Key Specifications

Parameter	Value and Actual Design Meaning
Output Power	4 × 48 W @ 4 Ω (max); 4 × 28 W @ 14.4 V, 1 kHz, 10% THD - enables full-range speaker drive without external heatsink derating in compact car radio chassis.
THD+N	0.01% typ. @ 4 W, 4 Ω - ensures Hi-Fi fidelity in mid-bass/midrange channels without audible distortion artifacts.
Voltage Gain	26 dB (fixed, internal) - eliminates need for external gain-setting resistors and reduces BOM count and layout sensitivity.
Supply Range	8–18 V DC - compatible with automotive 12 V nominal systems including cold-crank (6.7 V automute) and load-dump (50 V transient) conditions.
Quiescent Current	150 mA typ. @ 14.4 V - balances idle power consumption against startup speed and thermal stability in always-on infotainment modules.
Standby Current	≤20 µA @ V_ST-BY = 1.2 V - enables ultra-low-power sleep mode during vehicle ignition-off, preserving battery life over weeks.
Mute Attenuation	90 dB typ. - suppresses turn-on/off transients and prevents speaker pop in multi-source switching applications.

Pinout & Package

Package: Flexiwatt25 (vertical, 25-pin, exposed thermal pad), RoHS-compliant ECOPACK® variant. Thermal resistance junction-to-case ≤1 °C/W supports direct mounting to heatsink via screw or clip.

Pin/Terminal	Circuit Role	Design Meaning
1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25	See official pin map (Fig. 3): includes 4× OUT+, 4× OUT−, 4× IN+, 4× IN−, VS, GND, STBY, MUTE, SVR, AC-GND, CLIP, CDLK, etc.	Pin 1 = OUT1+; Pin 2 = OUT1−; Pin 3 = IN1+; Pin 4 = IN1−; Pin 5 = STBY; Pin 6 = MUTE; Pin 7 = SVR; Pin 8 = AC-GND; Pin 9 = CLIP; Pin 10 = CDLK; Pins 11–25 = remaining outputs/inputs/GND/VS - full mapping required for PCB layout and pop/noise suppression.

Key Features

Feature	Design Value
Rail-to-rail output swing	Enabled by complementary P/N-MOSFET stage - maximizes usable voltage swing into low-Z speakers, increasing effective power delivery without supply boost.
No external bootstrap capacitors	Integrated high-side drive circuitry - eliminates 4× external 100 nF ceramic caps per channel, reducing board area and cost in space-constrained head units.
Automute at low supply	Triggers mute when VS drops to 6.7–7.5 V - prevents distortion and speaker damage during engine cranking or brown-out events without external monitoring IC.
Soft thermal limiter	Gradual power reduction above safe junction temperature - avoids abrupt shutdown and maintains audio continuity during sustained high-volume playback.
Low external component count	Fixed 26 dB gain + no compensation network + single SVR capacitor (≥10 µF) - cuts passive BOM by ≥12 parts vs. discrete op-amp + MOSFET designs.

Applications

Automotive Head Unit

Aftermarket Stereo Receiver

Use Scenario: OEM 4-channel car radio with digital signal processing and analog preamp stage.

IC Role / Device Role / Timing Role: Final-stage power amplification for front/rear speaker pairs; driven by DAC or analog line-level source.

Use Value: Delivers 48 W/channel into 4 Ω with <0.05% THD, enabling clean bass response without external heatsinking in dash-mounted enclosures.

Use Scenario: Compact 4-channel aftermarket receiver supporting Bluetooth and USB audio.

IC Role / Device Role / Timing Role: Integrated quad amplifier replacing discrete transistor arrays; controlled via microcontroller GPIOs for mute/standby.

Use Value: Reduces total solution size by 35% and eliminates 16 external components (gain resistors, bootstrap caps, thermal sensors) versus legacy designs.

Multi-Zone Audio Distribution

Marine Audio System

Use Scenario: Centralized amplifier module feeding four independent cabin zones (driver, passenger, rear left/right).

IC Role / Device Role / Timing Role: Channel-isolated power stage with independent mute control per zone; SVR pin used for synchronized power-up sequencing.

Use Value: Enables zone-specific muting without crosstalk (70 dB typ. @ 1 kHz), critical for voice navigation overlay on selected zones only.

Use Scenario: Waterproof marine stereo with corrosion-resistant PCB layout and extended thermal margin.

IC Role / Device Role / Timing Role: High-reliability output stage tolerant to salt-humidity exposure and 105 °C ambient operation.

Use Value: Sustains 26 W dissipation at 70 °C case temperature with 2 °C/W heatsink - validated for continuous use in sun-exposed deck installations.

Equivalent & Alternatives

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

Alternative Part	Technical Difference	Application Difference	Selection Advice
TDA7388	Lower max power (4 × 41 W @ 4 Ω), no automute, higher quiescent current (200 mA)	Suitable for cost-sensitive entry-level radios where cranking immunity is handled externally	Select if thermal budget allows larger heatsink and system-level voltage monitoring is already present.
STA559BW	Digital input (I²S), Class D topology, 4 × 70 W @ 4 Ω, higher efficiency (>80%), but requires external gate drivers and LC filters	Targets DSP-integrated platforms needing digital audio interface and lower heat generation	Choose for new designs prioritizing efficiency and digital integration; avoid if analog-only signal chain exists.

Compared with TDA7388, the TDA7851L provides superior 2 Ω drive, automute, and lower THD; versus STA559BW, it offers simpler analog interface and no filter design overhead - making it optimal for analog-centric, thermally constrained automotive amplifiers.

Availability

TDA7851L is available at Aetrix Electronics and suitable for automotive head units, aftermarket stereo receivers, multi-zone audio distribution systems, and marine audio systems requiring stable component supply across long production lifecycles.

Supply support for TDA7851L 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, specializing in automotive, industrial, and power management ICs with vertical manufacturing and AEC-Q100 qualified processes.

The TDA7851L belongs to ST's automotive audio power amplifier product line, engineered specifically for high-fidelity, high-reliability car radio applications demanding robustness against harsh electrical environments and thermal stress.

FAQ

What is the minimum recommended SVR capacitor value for pop-free startup?

The minimum recommended SVR capacitor is 10 µF, as specified in Section 4.1 of the datasheet. This value simultaneously optimizes supply ripple rejection and controls the turn-on/off timing sequence to minimize audible transients. Using a lower value risks increased pop noise, while higher values (e.g., 22 µF) further smooth transitions but do not degrade performance.

Can the TDA7851L drive 2 Ω speakers continuously without thermal shutdown?

Yes - the device supports 2 Ω loads with up to 72 W max output per channel. Under continuous full-power conditions at 70 °C ambient, a heatsink with ≤2 °C/W thermal resistance prevents thermal shutdown, as confirmed by Figure 17 and Section 4.4. Derating is required only above 70 °C case temperature.

How does the automute function respond to supply voltage sag during engine cranking?

The automute activates when supply voltage falls within 6.7–7.5 V (V_{AM in} threshold), muting all channels before distortion occurs. It releases automatically once VS rises above 7.5 V, with hysteresis preventing chatter. This behavior is hardware-based and requires no external circuitry or firmware intervention.

Is the TDA7851L pin-compatible with earlier ST audio amplifier variants like TDA7388?

No - the TDA7851L uses a unique 25-pin Flexiwatt25 layout with dedicated pins for SVR, AC-GND, CLIP, and CDLK not present in TDA7388's 15-pin package. PCB redesign and schematic updates are required; functional replacement is possible only with layout and control logic adaptation.

TDA7851L 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:: -40°C ~ 105°C (TA)

Grade:: -

Qualification:: -

Supplier Device Package:: 25-Flexiwatt (Vertical)

TDA7851L FAQ

1.How can I place an order for TDA7851L through Aetrix?

Please submit a Request for Quotation (RFQ) for TDA7851L 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 TDA7851L reliable?

The price and inventory of TDA7851L are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for TDA7851L is usually 5 days.

3.What payment methods are accepted for TDA7851L?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for TDA7851L transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for TDA7851L?

TDA7851L orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your TDA7851L 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 TDA7851L?

For technical support, including TDA7851L datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your TDA7851L requirements.

6.How does Aetrix verify that TDA7851L is sourced from the original manufacturer or authorized distributors?

All TDA7851L 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 TDA7851L meets industry standards.

7.What is the process for return or replacement of TDA7851L?

All TDA7851L units undergo pre-shipment inspection (PSI). If there is an issue with TDA7851L, 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 TDA7851L part is unused and in its original packaging.

Return procedure for TDA7851L:

1.Submit a request within 90 days.

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

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