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TPA3244

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SLASEC6 – APRIL 2016

Product Folder Links: TPA3244

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Copyright © 2016, Texas Instruments Incorporated

Overview (continued)

The audio signal path including gate drive and output stage is designed as identical, independent half-bridges.

For this reason, each half-bridge has separate bootstrap pins (BST_X). Power-stage supply pins (PVDD_X) and

gate drive supply pins (GVDD_X) are separate for each full bridge. Although supplied from the same 12-V

source, separating to GVDD_AB, GVDD_CD, and VDD on the printed-circuit board (PCB) by RC filters (see

application diagram for details) is recommended. These RC filters provide the recommended high-frequency

isolation. Special attention should be paid to placing all decoupling capacitors 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

(BST_X) to the power-stage output pin (OUT_X). 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_X) 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. It is recommended to use 33-

nF ceramic capacitors, size 0603 or 0805, for the bootstrap supply. These 33nF capacitors ensure sufficient

energy storage, even during minimal PWM duty cycles, to keep the high-side power stage FET (LDMOS) fully

turned on during the remaining part of the PWM cycle.

Special attention should be paid to the power-stage power supply; this includes component selection, PCB

placement, and routing. As indicated, each full-bridge has independent power-stage supply pins (PVDD_X). For

optimal electrical performance, EMI compliance, and system reliability, it is important that each PVDD_X node is

decoupled with 1-

μF ceramic capacitor placed as close as possible to the supply pins. It is recommended to

follow the PCB layout of the TPA3244 reference design. For additional information on recommended power

supply and required components, see the application diagrams in this data sheet.

The 12-V supply should be from a low-noise, low-output-impedance voltage regulator. Likewise, the 36-V power-

stage supply is assumed to have low output impedance and low noise. The power-supply sequence is not critical

as facilitated by the internal power-on-reset circuit, but it is recommended to release RESET after the power

supply is settled for minimum turn on audible artefacts. Moreover, the TPA3244 device is fully protected against

erroneous power-stage turn on due to parasitic gate charging. Thus, voltage-supply ramp rates (dV/dt) are non-

critical within the specified range.