The TPA032D02 Class-D Audio Power Amplifier Evaluation Module
3-8
Details
3.2.4
Class-D Differential Inputs
The TPA032D02 EVM line inputs allow the use of a single-ended or differential
audio source. The differential input stage of the amplifier cancels any noise
that appears on both input lines of a channel. To use the EVM with a differential
source, connect the positive lead of the audio source to the RIN+/LIN+ inputs
and the negative lead to the RIN–/LIN– inputs. To use the EVM with a
single-ended source, connect the positive lead of the audio source to the
RIN+/LIN+ inputs and the ground lead to the RIN–/LIN– inputs. These
connections should only be made to the EVM input pins in order to keep the
input impedance of the class-D amplifiers balanced. This is due to the ac
coupling capacitors that are in series with the amplifier inputs.
3.2.5
Control and Indicator Circuits
Three main control circuits are provided with the TPA032D02. The mute circuit
grounds the output of the active amplifier, and the shutdown circuit places the
entire device into a power-saving sleep mode to minimize current
consumption. Each of these inputs is TTL compatible: less than 0.8 V applied
to these pins is considered a logic low, and any voltage greater than 2 V is
considered a logic high.
Two indicator pins are also provided for feedback when an under-voltage,
over-current, or thermal fault exists. Module pins are provided for easy
connection of off-board control and monitoring. There are two active low fault
indicator pins on the TPA032D02 amplifier IC (IC pins 40 and 41) that provide
feedback when a fault condition exists. Signals on these pins provide the
status of the class-D amplifier: operational, over-current, thermal fault, and
under-voltage lockout. Table 3–1 lists the possible output conditions of these
pins and a description of the fault indicated.
Table 3–1. TPA032D02 Class-D EVM Fault Indicator Table
FAULT 0
(TP 1)
FAULT 1
(TP 2)
DESCRIPTION
1
1
No fault. — The device is operating normally.
1
0
Charge pump under-voltage lockout (VCP-UV) fault — the charge pump voltage is < (PVDD + 6V).
All low-side transistors are turned on, shorting the load to ground. Normal operation resumes when
the charge pump voltage is restored (not a latched fault), however the Fault indication remains
active until cleared by cycling MUTE, SHUTDOWN, or the power supply.
0
1
Over-current fault — the output current limit has been exceeded. All output transistors are switched
off, causing the load to see a high impedance state. This is a latched fault and is cleared by cycling
MUTE, SHUTDOWN, or the power supply.
0
0
Thermal fault — the internal junction temperature has exceeded 125
°
C. All of the low-side
transistors are turned on, shorting the load to ground. Once the junction temperature drops by 20
°
C
and is below 125
°
C, normal operation resumes (not a latched fault). The Fault indication remains
active until cleared by cycling MUTE, SHUTDOWN, or the power supply.
Содержание TPA032D02
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