SLAAEM4 October 2025 TAS2120 , TAS2320
2 Internal and External Class-H
The TAS2x20 integrates an advanced Class-H boost control algorithm, which dynamically adjusts the boost supply with a minimum step size of 33mV by tracking the audio signal levels in real time. By reducing unnecessary power overhead, this approach significantly improves system efficiency and extends battery life—an important advantage for portable and power-sensitive designs.
The Class-H operation is enabled through the BST_MODE[1:0] register. The max boost voltage the device generates is controlled by VBOOST_MAX_CTRL[7:0] and can be configured with a step size of 66mV. In Class-H mode of operation, the boost voltage does not exceed this set value.
| BST_MODE [1:0] | BOOST MODE |
|---|---|
| 00 | Class-H – High efficiency (default) |
| 01 | Class-G – Low in-rush |
| 10 | Always On |
| 11 | Always Off – Pass-through |
| VBOOST_MAX_CTRL[7:0] | BOOST VOLTAGE (V) |
|---|---|
| 0x00 – 0x53 | Reserved |
| 0x54 | 5.54V |
| 0x55 | 5.61V |
| … | …steps of 66mV per LSB step… |
| 0xA7 | 11.02V |
| … | …steps of 66mV per LSB step… |
| 0xE3 | 14.98V (default) |
| 0xE4 | 15.05V |
| 0xE5 | 15.11V |
| 0xE6 – 0xFF | Reserved |
The algorithm incorporates signal buffering to provide the necessary look-ahead time, so the boost output capacitor is charged in advance; preventing clipping under dynamic audio conditions. This signal buffering continuously monitors the input signal and applies system-level parameters—such as boost output voltage, output capacitor size, and channel gain—configured through the PPC3 software. From this, PPC3 automatically computes the appropriate Class-H tuning coefficients and programs the coefficients into the CLASSH_TUNING_x[23:0] registers.
Figure 2-1 Class-H OperationThe TAS2120 and TAS2320 audio amplifier devices support Class-H operations, but differ in implementations of the necessary boost circuitry. The TAS2120 device has an integrated boost converter, enabling internal implementation of the Class-H control algorithm. This implementation allows for closed-loop control of the boost voltage directly within the device.
Conversely, the TAS2320 device does not have an integrated boost converter. Instead, the device provides a pulse-width modulation (PWM) control signal output designed to drive an external boost circuit. This external circuitry is then responsible for generating the Class-H boost output voltage.
This implementation distinction impacts the system design, with the TAS2120 offering a more compact design due to on-chip integration, while the TAS2320 offers greater flexibility in boost converter selection and configuration.