Texas Instruments TPA3003D2 - Manual (Page 24)

TPA3003D2
SLOS406A − FEBRUARY 2003 − REVISED MARCH 2003
24 www.ti.com
APPLICATION INFORMATION
differential input
The differential input stage of the amplifier cancels any noise that appears on both input lines of the channel.
To use the TPA3003D2 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 TPA3003D2 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.
using low-ESR capacitors
Low-ESR capacitors are recommended throughout this application section. A real (as opposed to ideal)
capacitor can be modeled simply as a resistor in series with an ideal capacitor. The voltage drop across this
resistor minimizes 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.
short-circuit protection
The TPA3003D2 has short circuit protection circuitry on the outputs that prevents damage to the device during
output-to-output shorts, output-to-GND shorts, and output-to-V
CC
shorts. When a short-circuit is detected on
the outputs, the output drive is immediately disabled. This is a latched fault and must be reset by cycling the
voltage on the SD pin to a logic low and back to the logic high state for normal operation. This will clear the
short-circuit flag and allow for normal operation if the short was removed. If the short was not removed, the
protection circuitry will again activate.
thermal protection
Thermal protection on the TPA3003D2 prevents damage to the device when the internal die temperature
exceeds 150
° C. There is a ± 15 degree tolerance on this trip point from device to device. Once the die
temperature exceeds the thermal set point, the device enters into the shutdown state and the outputs are
disabled. This is not a latched fault. The thermal fault is cleared once the temperature of the die is reduced by
20
° C. The device begins normal operation at this point with no external system interaction.
thermal considerations: output power and maximum ambient temperature
To calculate the maximum ambient temperature, the following equation may be used:
Θ
JA
= 45
°
C/W
where: T
J
= 150
°
C
T
Amax
= T
J
–
Θ
JA
P
Dissipated
(The derating factor for the 48-pin PFB package is given in the dissipation rating table.)
To estimate the power dissipation, the following equation may be used:
P
Dissipated
= P
O(average)
x ((1 / Efficiency) – 1)
Efficiency = ~75% for an 8-
Ω
load
(8)
(9)