TPA3002D2

SLOS402C − DECEMBER 2002 − REVISED JANUARY 2004

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The bootstrap capacitors connected between the BSxx pins and corresponding output function as a floating

power supply for the high-side N-channel power MOSFET gate drive circuitry. During each high-side switching

cycle, the bootstrap capacitors attempt to hold the gate-to-source voltage high enough to keep the high-side

MOSFETs turned on. However, there is a leakage path and the voltage on the bootstrap capacitors slowly

decrease while the high-side is conducting.

By driving the outputs into heavy clipping with a sine wave of less than 50 Hz, the bootstrap voltage can

on pins 25 and 36).

For the majority of applications, driving a square wave at low frequencies is not a design consideration and the

recommended bootstrap capacitor value of 10 nF is acceptable. However, if this is a concern, increasing the

bootstrap capacitors holds the gate voltage for a longer period of time and the drop in the output voltage does

not occur. A value of 220 nF is recommended with a 51

Ω resistor placed in series between the outputs and

bootstrap pins. The 51

Ω series resistor is necessary to limit the current charging and discharging the bootstrap

capacitors.

VCLAMP Capacitors

To ensure that the maximum gate-to-source voltage for the NMOS output transistors is not exceeded, two

internal regulators clamp the gate voltage. Two 1-

µF capacitors must be connected from VCLAMPL (pin 25)

and VCLAMPR (pin 36) to ground and must be rated for at least 25 V. The voltages at the VCLAMP terminals

preamplifier, and volume control circuitry. It requires a 0.1-

µF to 1-µF capacitor, placed very close to the pin,

to ground to keep the regulator stable. The regulator may be used to power an external headphone amplifier

or other circuitry, up to a current limit specified in the specification table. When powering external circuitry, like

the TPA6110A2 headphone amplifier, an additional 10

terminal.

AVCC

(pin 33)

Ch1

(AVDD)

Ch2

(AVCC)

AVDD

(pin 29)

Power−Up

Ch1 2 V/div

Ch2 5 V/div

M 10.0

µs

Figure 37. Power-Up Response

Differential Input

The differential input stage of the amplifier cancels any noise that appears on both input lines of the channel.

To use the TPA3002D2 EVM with a differential source, connect the positive lead of the audio source to the INP

input and the negative lead from the audio source to the INN input. To use the TPA3002D2 with a single-ended

source, ac ground the INP input through a capacitor equal in value to the input capacitor on INN and apply the

audio source to the INN input. In a single-ended input application, the INP input should be ac-grounded at the

audio source instead of at the device input for best noise performance.