9.1 Overview

To facilitate system design, the TPA3137D2 needs only a single power supply between 4.5 V and 14.4 V for operation. An internal voltage regulator provides suitable voltage levels for the gate driver, digital, and low-voltage analog circuitry. Additionally, all circuitry requiring a floating voltage supply, as in the high-side gate drive, is accommodated by built-in bootstrap circuitry with integrated boot strap diodes requiring only an external capacitor for each half-bridge.

The audio signal path, including the gate drive and output stage, is designed as identical, independent full-bridges. All decoupling capacitors should be placed as close to their associated pins as possible. In general, the physical loop with the power supply pins, decoupling capacitors and GND return path to the device pins must be kept as short as possible and with as little area as possible to minimize induction (see reference board documentation for additional information).

For a properly functioning bootstrap circuit, a small ceramic capacitor must be connected from each bootstrap pin (BSXX) to the power-stage output pin (OUTXX). When the power-stage output is low, the bootstrap capacitor is charged through an internal diode connected between the gate-drive power-supply pin (GVDD) and the bootstrap pins. When the power-stage output is high, the bootstrap capacitor potential is shifted above the output potential and thus provides a suitable voltage supply for the high-side gate driver. In an application with PWM switching frequencies in the range of 315 kHz, use ceramic capacitors with at least 220-nF capacitance, size 0603 or 0805, for the bootstrap supply. These capacitors ensure sufficient energy storage, even during clipped low frequency audio signals, to keep the high-side power stage FET (LDMOS) fully turned on during the remaining part of its ON cycle.

Special attention should be paid to the power-stage power supply; this includes component selection, PCB placement, and routing. For optimal electrical performance, EMI compliance, and system reliability, each PVCC pin should be decoupled with ceramic capacitors that are placed as close as possible to each supply pin. It is recommended to follow the PCB layout of the TPA3137D2 reference design. For additional information on recommended power supply and required components, see the application diagrams in this data sheet.

The PVCC power supply should have low output impedance and low noise. The power-supply ramp and SD release sequence is not critical for device reliability as facilitated by the internal power-on-reset circuit, but it is recommended to release SD after the power supply is settled for minimum turn on audible artifacts.