TDA7850 - 4x50W Quad Bridge Car Audio Amplifier | STMicroelectronics
MPN: TDA7850 ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $8.5 | $8.50 |
| 10 | $7.65 | $76.50 |
| 100 | $6.8 | $680.00 |
| 500 | $6.12 | $3,060.00 |
| 1,000 | $5.5 | $5,500.00 |
TDA7850 Overview
A class AB amplifier is a type of audio power amplifier that combines the efficiency of class B with the low distortion of class A, making it ideal for automotive head units where both power output and audio fidelity are critical. In the system hierarchy, the TDA7850 sits as the final power amplification stage, following the pre-amplifier and tone control stages, and drives the speakers directly.
Key features include a high output power of 4x50W at 4Ω, a wide supply voltage range of 8V to 18V, and a low quiescent current of 120mA. The device also features standby and mute functions for power management, a full set of protections including short-circuit, over-temperature, and load-dump protection, and a very low output noise of 50µV. The Flexiwatt-25 package provides excellent thermal performance with a thermal resistance of 1°C/W, enabling reliable operation in confined automotive environments.
The TDA7850 uses a complementary NPN/PNP output stage with a proprietary BiCMOS process, achieving a signal-to-noise ratio of 90dB and a total harmonic distortion of 0.006% at 1kHz. The high PSRR of 80dB minimizes alternator noise, ensuring clean audio output even with engine running. The device also includes a diagnostic pin for fault detection, simplifying system-level testing.
Typical applications include car radio head units, aftermarket car audio amplifiers, and marine audio systems. The high output power and low distortion make it suitable for driving 4Ω or 2Ω speakers in multi-channel configurations. The standby and mute pins allow for easy integration with microcontroller-based control systems.
When designing with this device, ensure adequate heatsinking to manage the thermal dissipation at high output power. The Flexiwatt-25 package requires a proper thermal interface to the chassis. Also, place the supply and output capacitors close to the IC to minimize EMI and ensure stable operation.
This page synthesizes distributor pricing, drop-in alternatives, and practical design notes not found in the ST datasheet, providing a comprehensive resource for engineers selecting a quad bridge amplifier.
Drop-in alternatives for TDA7850 — same package, pin-to-pin compatible. Different-package parts requiring PCB rework are excluded.
Variants in this series
Same-series models that are drop-in compatible with TDA7850 (same form factor and footprint) — differing in Package, Output Power, Protection Features, Mounting Type, Supply Voltage Range.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
TDA7851L
📋 Reference alternative (not in catalog)
TDA7850A
📋 Reference alternative (not in catalog)
TDA7850H
📋 Reference alternative (not in catalog)
TDA7850 Maximum Ratings & Electrical Characteristics
| Output Power | 4x50W at 4Ω, 14.4V |
| Supply Voltage Range | 8V to 18V |
| Quiescent Current | 120mA |
| Output Noise | 50µV |
| Signal-to-Noise Ratio | 90dB |
| Total Harmonic Distortion | 0.006% at 1kHz |
| PSRR | 80dB |
| Standby Current | 1µA |
| Mute Attenuation | 80dB |
| Operating Temperature | -40°C to +105°C |
| Package | Flexiwatt-25 |
| Mounting Type | Through Hole |
| Thermal Resistance | 1°C/W |
| RoHS Status | Compliant |
| Protection Features | Short-circuit, over-temperature, load-dump |
TDA7850 Pin Configuration
| Pin 1 | OUT1+ — Positive output channel 1 |
| Pin 2 | OUT1- — Negative output channel 1 |
| Pin 3 | GND — Ground |
| Pin 4 | OUT2+ — Positive output channel 2 |
| Pin 5 | OUT2- — Negative output channel 2 |
| Pin 6 | VS — Power supply |
| Pin 7 | OUT3+ — Positive output channel 3 |
| Pin 8 | OUT3- — Negative output channel 3 |
| Pin 9 | GND — Ground |
| Pin 10 | OUT4+ — Positive output channel 4 |
| Pin 11 | OUT4- — Negative output channel 4 |
| Pin 12 | VS — Power supply |
| Pin 13 | SVR — Supply voltage ripple rejection |
| Pin 14 | IN1 — Input channel 1 |
| Pin 15 | IN2 — Input channel 2 |
| Pin 16 | IN3 — Input channel 3 |
| Pin 17 | IN4 — Input channel 4 |
| Pin 18 | MUTE — Mute control |
| Pin 19 | STBY — Standby control |
| Pin 20 | DIAG — Diagnostic output |
| Pin 21 | GND — Ground |
| Pin 22 | GND — Ground |
| Pin 23 | GND — Ground |
| Pin 24 | GND — Ground |
| Pin 25 | GND — Ground |
Typical Applications
TDA7850 is suitable for 6 applications: Car Radio Head Units, Aftermarket Car Audio Amplifiers, Marine Audio Systems, Motorcycle Audio Systems, Home Theater Amplifiers, Public Address Systems.
Car Radio Head Units
The TDA7850 is ideal for car radio head units where high output power and low distortion are required. Its 4x50W output at 4Ω provides ample volume for in-car entertainment, while the low THD of 0.006% ensures clear audio reproduction. The wide supply voltage range (8V to 18V) accommodates battery voltage variations, and the standby/mute functions enable efficient power management. The Flexiwatt-25 package with low thermal resistance (1°C/W) allows reliable operation in the confined space of a head unit, with proper heatsinking to the chassis. The diagnostic pin simplifies system-level fault detection, making it a preferred choice for OEM and aftermarket head units.
Recommended
Aftermarket Car Audio Amplifiers
In aftermarket car audio amplifiers, the TDA7850 delivers high power to drive aftermarket speakers and subwoofers. Its 4x50W output can be bridged to 2x100W for more demanding setups. The low output noise of 50µV ensures a quiet background, and the high PSRR of 80dB rejects alternator noise. The device's protection features (short-circuit, over-temperature, load-dump) safeguard the amplifier and speakers in harsh automotive environments. The Flexiwatt-25 package allows for compact amplifier designs with external heatsinks, and the mute function prevents pop noise during power-up. This makes the TDA7850 a popular choice for DIY and professional aftermarket installations.
Recommended
Marine Audio Systems
The TDA7850 is suitable for marine audio systems where reliability and power are essential. Its supply voltage range of 8V to 18V matches marine battery systems, and the protection features guard against voltage transients common in marine environments. The low quiescent current (120mA) and standby current (1µA) help conserve battery power when the system is idle. The Flexiwatt-25 package, when properly conformal-coated, can withstand the humid and corrosive conditions of marine use. The high output power (4x50W) ensures clear audio over engine noise, and the low THD maintains audio fidelity. This makes the TDA7850 a robust choice for boat audio systems.
Recommended
Motorcycle Audio Systems
The TDA7850 can be used in motorcycle audio systems to provide high-power audio in a compact form factor. Its 4x50W output can drive handlebar speakers or fairing-mounted speakers with ease. The wide supply voltage range (8V to 18V) accommodates the varying voltage from a motorcycle's electrical system, and the standby function reduces battery drain when the engine is off. The low thermal resistance (1°C/W) allows the amplifier to be mounted on a heatsink that can be integrated into the motorcycle's bodywork. The mute function prevents pop noise during startup, and the diagnostic pin aids in troubleshooting. This makes the TDA7850 a viable option for motorcycle audio enthusiasts.
Recommended
Home Theater Amplifiers
The TDA7850 can be repurposed for home theater amplifiers, providing 4 channels of 50W output for surround sound systems. Its low THD (0.006%) and high SNR (90dB) ensure high-fidelity audio reproduction. The supply voltage range (8V to 18V) requires a suitable DC power supply, and the Flexiwatt-25 package can be mounted on a heatsink for efficient cooling. The standby and mute functions are useful for power management in a home theater setup. The diagnostic pin can be used for system monitoring. While not optimized for home use, the TDA7850 offers a cost-effective solution for DIY home theater amplifiers.
Recommended
Public Address Systems
The TDA7850 is suitable for small public address systems, such as those used in schools, offices, or small venues. Its 4x50W output can drive multiple speakers for clear announcements. The high PSRR (80dB) ensures clean audio even with noisy power supplies, and the low output noise (50µV) prevents background hiss. The protection features (short-circuit, over-temperature) ensure reliable operation in continuous use. The Flexiwatt-25 package allows for easy mounting on a heatsink, and the standby function can be used to save power when the system is idle. This makes the TDA7850 a versatile choice for PA applications.
Recommended
Recommended Products Summary
Engineering reference data for TDA7850 — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | TDA7851L | TDA7850A | TDA7850H |
|---|---|---|---|---|
| Package | Flexiwatt-25 | Flexiwatt-25 - same | Flexiwatt-25 - same | Flexiwatt-25 - same |
| Output Power (4Ω) | 4x50W | 4x45W | 4x50W | 4x50W |
| Supply Voltage Range | 8V to 18V | 8V to 18V | 8V to 18V | 8V to 18V |
| Quiescent Current | 120mA | 120mA | 120mA | 120mA |
| Total Harmonic Distortion | 0.006% | 0.006% | 0.006% | 0.006% |
| Signal-to-Noise Ratio | 90dB | 90dB | 90dB | 90dB |
| Standby Current | 1µA | 1µA | 1µA | 1µA |
| Diagnostic Pin | Yes | Yes | Yes (different behavior) | Yes |
Key Differentiators
- Higher output power than TDA7851L (vs TDA7851L)
- Standard diagnostic pin behavior (vs TDA7850A)
- Balanced performance and current capability (vs TDA7850H)
Design Notes
At 4x50W output, the TDA7850 can dissipate up to 30W of heat. The Flexiwatt-25 package has a thermal resistance of 1°C/W (junction-to-case), so a heatsink with a thermal resistance of less than 3°C/W is recommended to keep the junction temperature below 150°C. Ensure proper thermal interface material between the package tab and heatsink.
Place the supply decoupling capacitors (100µF electrolytic and 100nF ceramic) as close as possible to the VS pins. The output filter inductors (if used) should be placed near the output pins to minimize EMI. Use a star-ground topology to avoid ground loops and reduce noise.
Do not operate the TDA7850 without a heatsink, as it will overheat and trigger thermal shutdown. Ensure the standby and mute pins are properly controlled to avoid pop noise. The diagnostic pin is an open-collector output; use a pull-up resistor to VCC.
Compliance Information
RoHS compliant per STMicroelectronics product page. Not AEC-Q100 qualified, but designed for automotive applications.
