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3.4 Control and Indicator Circuits
Three main control circuits are provided with the TPA032D03. The mute circuit
grounds the output of the active amplifier, the mode circuit selects between the
class-D amplifier and the headphone 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 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
TPA032D03 amplifier IC (IC pins 41 and 42) that provide feedback when a fault
condition exists. Signals on these pins provide the status of the acvtive
amplifier: operational, thermal fault, and under-voltage lockout. Table 3–2 lists
the possible output conditions of these pins and a description of the fault
indicated.
Table 3–2. TPA032D03 Class-D EVM Fault Indicator Table
FAULT 0
FAULT 1
(TP 1)
(TP 2)
1
1
No fault. — The device is operating normally.
0
1
Charge pump under-voltage lockout (VCP-UV) fault. 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
0
Thermal fault. All of the low-side transistors are turned on, shorting the load to ground. Once the
junction temperature drops by 20 C, normal operation resumes (not a latched fault). The Fault
indication remains active until cleared by cycling MUTE, SHUTDOWN, or the power supply.
3.5 TPA032D03 Class-D EVM Test Points
Test points have been included on the TPA032D03 class-D EVM to facilitate
user analysis of device performance and design adjustments. Table 3–3 lists
each test point and its corresponding function.
Table 3–3. TPA032D03 Class-D EVM Test Points
TEST
POINT
IC PIN or EVM
FUNCTION
1
HPVCC
Onboard 5-V supply
2
FAULT_1
MSB for logic-level fault output signal, open drain
3
FAULT_0
LSB for logic-level fault output signal, open drain
Plug-N-Play Platform Inputs and Outputs
DESCRIPTION
FUNCTION
Details
3-5
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