WT8673 Audio Amplifier IC
80W Mono (PBTL) / 2×42W Stereo · 5–26V · 92% Efficiency · ESOP16
The WT8673 is a high‑power, stereo/mono switchable Class‑D audio amplifier designed for premium home audio and multimedia systems. It delivers 80W in PBTL mono mode or 2×42W in stereo mode (both at 24V, 4Ω load, THD+N ≤ 10%). Featuring advanced spread‑spectrum EMI suppression, it requires only low‑cost ferrite bead filters for EMC compliance. With 92% efficiency, it eliminates the need for bulky heatsinks in most applications. The device operates over a wide 5–26V supply range, includes comprehensive over‑current, short‑circuit, and thermal protection with auto‑recovery, and is housed in a thermally‑enhanced ESOP16 package. Its fixed gain of 24× (with internal 15k/360k resistors) simplifies design, making it perfect for LCD TVs, multimedia speakers, and home theater systems.
- 80W mono (PBTL) / 2×42W stereo @ 24V, 4Ω
- 92% efficiency – no heatsink required
- 5–26V wide supply range
- Spread‑spectrum EMI suppression
- Fixed 24× gain (internal resistors)
- ESOP16 package with thermal pad
WT8673 Key Features
Electrical Specifications (TA = 25°C)
| Parameter | Conditions | Min | Typ | Max | Unit |
|---|---|---|---|---|---|
| Supply Voltage | — | 5 | — | 26 | V |
| Quiescent Current | VCC=12V, no load | — | 6.5 | 9 | mA |
| Shutdown Current | CTRL=0V | — | 20 | 50 | µA |
| Output Power (Stereo) | RL=8Ω, 21V, THD+N≤10% | — | 33 | — | W/Ch |
| Output Power (Stereo) | RL=8Ω, 24V, THD+N≤10% | — | 42.5 | — | W/Ch |
| Output Power (PBTL Mono) | RL=4Ω, 24V, THD+N≤10% | — | 82.2 | — | W |
| THD+N | 14V, 8Ω, 12W, f=1kHz | — | 0.1 | — | % |
| PSRR | 1kHz, 200mVPP ripple | — | 70 | — | dB |
| Efficiency | — | — | 92 | — | % |
| Oscillator Frequency | — | — | 300 | — | kHz |
| Thermal Shutdown | — | 150 | 170 | 190 | °C |
| Start‑up Time | VCC=12V | — | 100 | — | ms |
| Gain (Fixed) | — | — | 24× | — | V/V |
PBTL mono mode requires paralleling the two output stages for higher current capability. Refer to the application schematic.
Pin Description – ESOP16
| Pin | Name | Function |
|---|---|---|
| 1 | PVCC | Power supply (5–26V) |
| 2 | CTRL | Enable / mode select (high = active, low = shutdown; 1.2–1.8V = spread spectrum) |
| 3 | INPL | Left channel positive input |
| 4 | INNL | Left channel negative input |
| 5 | GVDD | Gate drive voltage (bootstrap supply) |
| 6 | INNR | Right channel negative input |
| 7 | INPR | Right channel positive input |
| 8 | PVCC | Power supply (5–26V) |
| 9 | BSPR | Right positive bootstrap |
| 10 | OUTPR | Right positive output |
| 11 | BSNR | Right negative bootstrap |
| 12 | OUTNR | Right negative output |
| 13 | OUTNL | Left negative output |
| 14 | BSNL | Left negative bootstrap |
| 15 | OUTPL | Left positive output |
| 16 | BSPL | Left positive bootstrap |
| 0 (Pad) | PGND | Power ground – exposed pad, must be soldered with large copper area |
For PBTL mono mode, connect OUTPL to OUTPR and OUTNL to OUTNR, and drive both inputs in parallel. Refer to the application diagram.
Control & Spread Spectrum Modes
| CTRL Voltage | Mode |
|---|---|
| < 0.2V | Shutdown – < 50µA |
| 1.2V – 1.8V | Active + Spread Spectrum – reduced EMI |
| > 1.8V | Active (no spread spectrum) – fixed frequency |
Spread‑spectrum modulation spreads the switching frequency around 300kHz (±30kHz), reducing peak EMI energy.
Protection & Safety
- Over‑Current Protection (OCP): Shuts down output during short circuits or excessive current.
- Short‑Circuit Protection: Protects against output shorts to ground or supply.
- Thermal Shutdown (TSD): Disables output when temperature exceeds ~150°C (with ±15°C hysteresis). Auto‑recovers after temperature drops by 20°C.
- Auto‑Recovery: The device restarts normal operation automatically after fault conditions are removed (110ms recovery time).
Design & Layout Recommendations
Key design guidelines:
- Decoupling: Use a 10µF and 0.1µF ceramic capacitor close to each PVCC pin. A bulk capacitor (≥470µF) is recommended for low‑frequency filtering.
- Input configuration: For differential input, connect IN+ and IN− to the source. For single‑ended, connect IN− to ground through a capacitor and apply signal to IN+.
- Output filter: A low‑cost ferrite bead filter (e.g., 33µH + 1µF) is sufficient for most EMC requirements. For strict EMC, use an LC filter (inductor ≥33µH, 4.8A).
- Thermal management: The exposed pad (PGND) must be soldered to a large copper ground plane with multiple thermal vias (1mm spacing) for heat dissipation.
- Output RC snubber: For supply voltages above 22V, add a 10Ω + 2.2nF RC network across the output to improve system reliability.
- Bootstrapping: Connect 100nF capacitors between each bootstrap pin (BSPx/BSNx) and the corresponding output pin.
For EMC compliance, add an LC π‑filter (10–22µH, 4.8A) on the supply line and separate analog/digital grounds with a 0Ω resistor or ferrite bead.
WT8673 Applications
Why Choose WT8673
FAQs
What is the WT8673?
A high‑power Class‑D amplifier capable of 80W mono (PBTL) or 2×42W stereo operation with 92% efficiency and 5–26V supply.
What is the supply voltage range?
5V to 26V, suitable for both USB and high‑voltage power supplies.
What is the difference between stereo and PBTL modes?
Stereo mode drives two independent speakers (left/right). PBTL mode bridges both outputs for mono high‑current drive, doubling the power capability.
Does WT8673 need a heatsink?
No – its 92% efficiency and low thermal resistance allow operation without a heatsink in most applications.
What is the gain?
Fixed 24× (24V/V) with internal 15kΩ input and 360kΩ feedback resistors.
Can I use single‑ended input?
Yes – connect IN− to ground through a capacitor and apply signal to IN+.
What output filter is required?
A simple ferrite bead filter is sufficient for most EMC requirements; an LC filter is recommended for stricter certification.
What protection features are included?
Over‑current, short‑circuit, thermal shutdown, and auto‑recovery after faults.
What is the WT8673 package?
ESOP16 with an exposed pad for thermal dissipation.
Note: For supply voltages above 22V, add a 10Ω + 2.2nF RC snubber at the output. The exposed pad (PGND) must be soldered to a large copper area with multiple vias for proper heat dissipation. When using PBTL mono mode, follow the recommended parallel output connection. Refer to the datasheet for complete application schematics, characteristic curves, and detailed PCB layout guidelines.
