TDA7256 - 30W Class-AB Bridge Car-Radio Amplifier | STMicroelectronics
MPN: TDA7256 ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $3.92 | $3.92 |
| 10 | $3.41 | $34.10 |
| 100 | $2.78 | $278.00 |
| 500 | $2.34 | $1,170.00 |
| 1,000 | $1.95 | $1,950.00 |
TDA7256 Overview
A class-AB bridge (BTL) audio power amplifier is a topology in which the IC drives both ends of the loudspeaker differentially, quadruating the voltage swing that can be developed across the load compared with a single-ended output. This allows far higher output power from low-voltage automotive supplies (typically 6 V to 18 V) without a step-up converter. The category sits under: audio amplifier IC -> amplifier -> signal chain IC -> semiconductor. Within the car-radio ecosystem, the TDA7256 is most often used as the system-level power stage that follows a pre-amp/tone-control block and feeds the cabin speakers.
Key features include 30 W continuous output into a 4 Ω bridge load (THD = 10%), drive capability down to 2 Ω, differential inputs for superior PSRR and ground-noise rejection, very low standby current consumption, TTL-compatible mute and standby logic, programmable turn-on delay to suppress pops, and full protection: speaker-to-ground, output-to-Vs, output short, load-dump, and overtemperature. The Multiwatt-11 package has an integrated metal tab that provides a low thermal resistance path to an external heatsink, mandatory at high continuous output levels.
Internally the TDA7256 uses a complementary bipolar output stage and a fixed-gain differential input stage. The BTL topology removes the need for a large output coupling capacitor, enabling true 0 dB low-frequency response, while the high common-mode rejection of the differential input rejects alternator whine on the supply rail. Quiescent current is purposely biased into class-AB for a good efficiency-versus-distortion trade-off.
Typical applications are automotive head-unit power amplifiers, booster amplifiers for OEM and aftermarket car radios, marine/ATV audio systems, and any mono high-power audio channel fed from a 12 V battery bus. The device is also found in PA accessories and 12 V-powered subwoofer plates.
When designing with the TDA7256, always mount the tab to an adequate heatsink and observe the 2 Ω minimum load. Use the standby pin for pop-free power-up sequencing and wire the mute pin low during supply transients to avoid turn-on clicks. Source bypass capacitors must be placed as close as possible to the supply pin to handle the high peak currents that class-AB output stages demand.
Drop-in alternatives for TDA7256 — 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 TDA7256 (same form factor and footprint) — differing in Mounting Type, Output Power, Package, Short-Circuit Protection.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
E-TDA7391PDTR
✅ Drop-In✓ In Stock
$3.36 / Unit
View Datasheet →TDA2003
✅ Drop-In ⚠️ Specs Unverified📋 Reference alternative (not in catalog)
TDA7256 Maximum Ratings & Electrical Characteristics
| Product Type | Class-AB Bridge Audio Power Amplifier |
| Output Channels | 1 (Mono, BTL) |
| Topology | Bridge-Tied Load (BTL), Class-AB |
| Output Power | 30 W into 4 ohm at THD 10% |
| Minimum Load Impedance | 2 ohm |
| Supply Voltage (Vs) | [6 - 18 V] |
| Input Type | Differential |
| Mute / Standby Logic | TTL compatible |
| Standby Current | Very low (standby mode) |
| Turn-on Delay | Programmable |
| Short-Circuit Protection | RL short, OUT to GND, OUT to Vs |
| Load-Dump Protection | Yes |
| Thermal Shutdown | Yes |
| Package | Multiwatt-11 (vertical, with tab) |
| Mounting Type | Through-hole (with heatsink) |
| RoHS Status | Compliant |
TDA7256 Pin Configuration
| Pin 1 | ST-BY — Standby logic input (TTL) |
| Pin 2 | MUTE — Mute logic input (TTL) |
| Pin 3 | IN+ — Differential audio input non-inverting |
| Pin 4 | IN- — Differential audio input inverting |
| Pin 5 | GND — Ground |
| Pin 6 | SVR — Supply voltage rejection / turn-on delay capacitor |
| Pin 7 | Vs — Supply voltage |
| Pin 8 | OUT+ — Bridge output non-inverting |
| Pin 9 | OUT- — Bridge output inverting |
| Pin 10 | GND — Ground |
| Pin 11 | TAB — Metal tab - thermal/ground return (must be heatsinked) |
Typical Applications
TDA7256 is suitable for 6 applications: Car-radio head-unit main channel, Aftermarket car-radio booster, 12 V subwoofer plate amplifier, Marine and powersport audio, PA accessory and 12 V public-address add-on, Industrial 24 V audio alarm driver.
Car-radio head-unit main channel
The TDA7256 is the canonical power stage for a 12 V automotive head-unit main channel, delivering 30 W into a 4 ohm cabin speaker in bridge-tied load. Its 2 ohm drive capability handles dual-8-ohm speaker loads wired in parallel for OEM install bays, and the differential input rejects alternator whine on the chassis ground. The TTL-compatible mute and programmable turn-on delay suppress turn-on thump when the head unit wakes from standby. For a 4-channel head unit, four TDA7256 parts in parallel drive front L, front R, rear L, rear R with a single heatsink bracket - the integrated load-dump and short-circuit protections are exactly what automotive EMC qualification demands.
Recommended
Aftermarket car-radio booster
An aftermarket booster amplifier adds 30 W per channel to an existing OEM radio by tapping the speaker-level output and feeding a TDA7256 per channel. The TDA7256's differential input accepts the bridge-tied speaker-level signal directly with a simple resistor divider, eliminating the need for a line-output converter on most installs. The Multiwatt-11 tab bolts to the booster's aluminum chassis, which doubles as the heatsink for 30 W continuous music power. Internal short-circuit and thermal protection make the booster tolerant of the wiring mistakes that plague DIY car-audio installation.
Recommended
12 V subwoofer plate amplifier
The TDA7256 drives a 2 ohm subwoofer voice coil directly from a 12 V battery, producing roughly twice the power into 2 ohm that it does into 4 ohm in BTL mode. The Multiwatt-11 tab mounts to a small aluminum extrusion that doubles as the plate amplifier's structural chassis. For sustained deep-bass use, the class-AB efficiency penalty is significant - designers often pair the TDA7256 with a class-D main stage and use the TDA7256 only on the sub channel where simplicity and pop-free turn-on matter more than battery drain.
Recommended
Marine and powersport audio
Marine and powersport audio systems run on the same 12 V battery bus as a car but face harsher environments - salt spray, vibration, voltage transients from the alternator, and intermittent load-dump events from the regulator. The TDA7256's load-dump and short-circuit protection suite was designed for this environment, and the Multiwatt-11 tab mounting is mechanically robust against vibration. Boat and ATV OEMs use TDA7256 in mono zone amplifiers that feed wakeboard tower speakers and handlebar speaker pods where 30 W of clean audio is more than enough to overcome wind and water noise.
Recommended
PA accessory and 12 V public-address add-on
A 12 V powered PA accessory - a megaphone-style bulletin board, a kiosk audio driver, or a construction-site call-out box - uses a TDA7256 as its single-IC 30 W power stage. The IC's single-supply operation, low standby current, and TTL mute/standby let the host microcontroller put the amplifier to sleep between announcements. Because the load is typically a single 4 ohm weatherproof driver, the 30 W figure provides comfortable headroom for intelligibility in outdoor and high-ambient-noise environments.
Recommended
Industrial 24 V audio alarm driver
Industrial alarm panels often need to drive a high-SPL piezo horn or a 4 ohm loudspeaker from a 24 V back-up bus. The TDA7256's 18 V absolute-max supply rating requires a small pre-regulator or a series-drop resistor on 24 V systems, but in return it provides short-circuit, thermal and load-dump protection that an industrial alarm board needs to pass CE/IEC EMC testing. The mute/standby TTL logic lets the alarm controller cut audio cleanly between alerts without the pop-noise that would otherwise trigger false operator suspicion.
Recommended
Recommended Products Summary
Engineering reference data for TDA7256 — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | TDA7391 | TDA2003 |
|---|---|---|---|
| Brand | STMicroelectronics | STMicroelectronics | STMicroelectronics |
| Package | Multiwatt-11 | Multiwatt-15 | TO-220-5 |
| Output Power | 30 W into 4 ohm BTL | 35 W into 4 ohm BTL | 10 W into 2 ohm SE |
| Topology | Class-AB BTL | Class-AB BTL | Class-AB SE |
| Min Load | 2 ohm | 2 ohm | 1.6 ohm |
| Channels | 1 (Mono) | 1 (Mono) | 1 (Mono) |
| Mute/Standby | TTL compatible | TTL compatible | None |
| Pin-Compatible Drop-In | Reference | No (Multiwatt-15 vs 11) | No (TO-220-5 vs Multiwatt-11) |
Key Differentiators
- 30 W BTL at 2 ohm minimum load in Multiwatt-11 (vs TDA2003 (TO-220-5, 10 W SE))
- Differential input with TTL mute/standby (vs TDA2003)
- 30 W continuous music power per channel at 12 V (vs TDA7391 (Multiwatt-15, 35 W))
Design Notes
At 30 W into 4 ohm BTL from a 14.4 V supply, the TDA7256 will dissipate several watts internally as class-AB losses. The Multiwatt-11 tab is the primary thermal path - it MUST be bolted to an external aluminum heatsink or a substantial chassis surface with thermal compound. Without a heatsink the thermal-shutdown protection will trigger under sustained high output, causing audible dropouts. Estimate: 1 square inch of 1.5 mm aluminum extrusion keeps the junction below 100 C at 25 C ambient with continuous music power.
Place the Vs (pin 7) supply bypass capacitor as close as physically possible to the IC pin with a wide, heavy-trace return to the GND pins (5 and 10). Use a 100 nF ceramic in parallel with a 1000 uF or larger electrolytic for class-AB peak-current handling. The SVR capacitor (pin 6) sets the turn-on delay and supply-rejection corner - do not omit it; typical value is 10 uF with a 100 kohm input impedance. Route the differential input pair (pins 3 and 4) as a tightly coupled pair and keep them away from the output traces to avoid instability.
Do not connect a 4 ohm speaker between OUT+ and OUT- while simultaneously shorting either output to ground - the internal short-circuit protection will engage, but sustained fault conditions can still damage the IC. Do not exceed the absolute-maximum Vs rating (typically 18 V) - the load-dump protection clamps transients above ~40 V, but a sustained 24 V supply will destroy the device. Always sequence the standby pin HIGH after Vs has stabilized to prevent the mute pin from releasing before the bias network is settled, which causes turn-on pop.
Compliance Information
RoHS and REACH compliant per ST product page. Not formally AEC-Q100 qualified - automotive qualification is via ST's broader car-radio amplifier portfolio process. Lead-free Multiwatt-11 package.
