WT4890 Audio Amplifier IC
1W AB‑Class · 0.1µA Shutdown · 2.2–5.5V · MSOP8 · High PSRR
The WT4890 is a high‑quality AB‑class audio power amplifier designed for portable and battery‑powered devices. It delivers 1W of continuous average power into an 8Ω load at 5V with less than 1% THD+N (20Hz–20kHz). The device features an ultra‑low 0.1µA shutdown current, wide supply voltage range (2.2–5.5V), and excellent PSRR (70dB at 217Hz and 1kHz). Its pop‑and‑click suppression circuitry eliminates audible transients during power‑up/down and playback start/stop. Housed in a compact MSOP8 package, it requires minimal external components and is ideal for mobile phones, PDAs, and other portable electronics.
- 1W output @ 5V, 8Ω, THD+N < 1%
- 0.1µA shutdown current
- 2.2–5.5V wide supply range
- High PSRR – 70dB @ 217Hz/1kHz
- Pop suppression – no audible transients
- MSOP8 miniature package
Key Features
Electrical Specifications (VCC = 5V, TA = 25°C)
| Parameter | Conditions | Min | Typ | Max | Unit |
|---|---|---|---|---|---|
| Supply Voltage | — | 2.2 | 5 | 5.5 | V |
| Quiescent Current | VIN=0V, no load | — | 4 | 8 | mA |
| Shutdown Current | VSD=0V | — | 0.1 | 2.0 | µA |
| Output Power (8Ω) | THD+N ≤ 1%, f=1kHz | 0.8 | 1.0 | — | W |
| Output Power (4Ω) | THD+N ≤ 1%, f=1kHz | — | — | — | W |
| THD+N | PO=0.4W, f=1kHz, 8Ω | — | 0.1 | — | % |
| PSRR | Vripple=200mVPP, f=217Hz | 55 | 62 | — | dB |
| PSRR | Vripple=200mVPP, f=1kHz | — | 66 | — | dB |
| Shutdown High Level | — | 1.2 | — | — | V |
| Shutdown Low Level | — | — | — | 0.4 | V |
| Wake‑up Time | — | — | 170 | 220 | ms |
| Thermal Shutdown | — | 150 | 170 | 190 | °C |
For 3V and 2.6V performance, refer to the datasheet. All values are typical unless noted.
Pin Description – MSOP8
| Pin | Name | Function |
|---|---|---|
| 1 | SD | Shutdown (high = active, low = shutdown) |
| 2 | BYP | Bypass capacitor for internal reference |
| 3 | +IN | Non‑inverting input |
| 4 | −IN | Inverting input |
| 5 | VO1 | Negative output (BTL) |
| 6 | VDD | Power supply (2.2–5.5V) |
| 7 | GND | Ground |
| 8 | VO2 | Positive output (BTL) |
The device uses a bridge‑tied load (BTL) configuration. Outputs are differential and should not be grounded.
Typical Application & Design Notes
Key design recommendations:
- Use a bypass capacitor (CBYP) on pin 2 for optimal PSRR and noise performance.
- Place supply decoupling capacitors (CS) as close as possible to the VDD pin.
- Set gain with external resistors: AV = −RF / RIN (typical RF = 20kΩ, RIN = 10kΩ for gain = 2).
- Use a series resistor and capacitor on the input to create a high‑pass filter (cutoff frequency = 1/(2π RIN CIN)).
- Keep audio traces away from interference sources (antennas, PWM, high‑frequency signals).
- Route output traces short and wide (≥1mm) for low impedance.
For EMC compliance, add a LC π‑filter (10–22µH, 0.5A) on the supply line and use 0Ω resistors or ferrite beads for analog/digital ground separation.
Applications
Why Choose WT4890
FAQs
What is the WT4890?
A high‑performance AB‑class audio amplifier delivering 1W into 8Ω at 5V with ultra‑low shutdown current and pop suppression.
What is the WT4890 supply voltage range?
2.2V to 5.5V, suitable for both battery and USB‑powered devices.
How much current does WT4890 draw in shutdown?
Less than 0.1µA typical, preserving battery life.
What is the output power at lower voltages?
At 3V: 0.31W (8Ω, THD+N<1%); at 2.6V: 0.2W (8Ω) / 0.22W (4Ω).
Does WT4890 require output coupling capacitors?
No, the BTL output eliminates the need for large DC‑blocking capacitors.
How can I control shutdown?
By applying a logic high (>1.2V) to the SD pin for normal operation, or low (<0.4V) to shut down.
Can I adjust the gain?
Yes, by changing the ratio of feedback resistor (RF) to input resistor (RIN).
What is the package type?
MSOP8, a small‑outline package with 8 leads.
Note: For optimal performance, place bypass capacitors close to the IC, keep input traces away from noise sources, and ensure proper grounding. The device is designed for portable applications and works reliably across the full temperature range (–40°C to +85°C). Refer to the datasheet for detailed characterization curves and layout guidelines.
