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BSN and BSP Capacitors
VCLAMP Capacitors
Internal Regulated 5-V Supply (AV
DD
)
Differential Input

SHUTDOWN OPERATION

USING LOW-ESR CAPACITORS

TPA3008D2
SLOS435A – MAY 2004 – REVISED JULY 2004
The full H-bridge output stages use only NMOS transistors. Therefore, they require bootstrap capacitors for thehigh side of each output to turn on correctly. A 220-nF ceramic capacitor, rated for at least 25 V, must beconnected from each output to its corresponding bootstrap input. Specifically, one 220-nF capacitor must beconnected from xOUTP to xBSP, and one 220-nF capacitor must be connected from xOUTN to xBSN. (See theapplication circuit diagram in Figure 16 .)
The bootstrap capacitors connected between the BSxx pins and corresponding output function as a floatingpower supply for the high-side N-channel power MOSFET gate drive circuitry. During each high-side switchingcycle, the bootstrap capacitors hold the gate-to-source voltage high enough to keep the high-side MOSFETsturned on.
To ensure that the maximum gate-to-source voltage for the NMOS output transistors is not exceeded, twointernal regulators clamp the gate voltage. Two 1-µF capacitors must be connected from VCLAMPL (pin 25) andVCLAMPR (pin 36) to ground and must be rated for at least 25 V. The voltages at the VCLAMP terminals varywith V
CC
and may not be used for powering any other circuitry.
The AV
DD
terminal (pin 29) is the output of an internally generated 5-V supply, used for the oscillator,preamplifier, and volume control circuitry. It requires a 1-µF capacitor, placed close to the pin, to keep theregulator stable.
This regulated voltage can be used to control GAIN0 and GAIN1 terminals, but should not be used to driveexternal circuitry.
The differential input stage of the amplifier cancels any noise that appears on both input lines of the channel. Touse the TPA3008D2 with a differential source, connect the positive lead of the audio source to the INP input andthe negative lead from the audio source to the INN input. To use the TPA3008D2 with a single-ended source, acground the INP or INN input through a capacitor equal in value to the input capacitor on INN or INP and applythe audio source to either input. In a single-ended input application, the unused input should be ac grounded atthe audio source instead of at the device input for best noise performance.
The TPA3008D2 employs a shutdown mode of operation designed to reduce supply current (I
CC
) to the absoluteminimum level during periods of nonuse for power conservation. The SHUTDOWN input terminal should be heldhigh (see specification table for trip point) during normal operation when the amplifier is in use. PullingSHUTDOWN low causes the outputs to mute and the amplifier to enter a low-current state. Never leaveSHUTDOWN unconnected, because amplifier operation would be unpredictable.
For the best power-off pop performance, place the amplifier in the shutdown mode prior to removing the powersupply voltage.
Low-ESR capacitors are recommended throughout this application section. A real (as opposed to ideal) capacitorcan be modeled simply as a resistor in series with an ideal capacitor. The voltage drop across this resistorminimizes the beneficial effects of the capacitor in the circuit. The lower the equivalent value of this resistance,the more the real capacitor behaves like an ideal capacitor.
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