Filter
Top Products
Si824xClassD-KIT
Rev. 0.2 5
Figure 6. Over Current Protection Circuit
4.5. Undervoltage Protection
The undervoltage protection comparator monitors the positive bus voltage and releases the undervoltage lockout
when the voltage is above 37 V. The amplifier starts up after a one-second delay. Note that the red LED remains lit
when the amplifier is in shutdown mode and turns off when the amplifier is enabled.
4.6. Other Features
A protection circuit jumper (JP 3) option is included that allows the amplifier to be manually shut down. This jumper
can be replaced with a switch or other control circuit, allowing the amplifier to be muted. The one-second
undervoltage lockout delay allows the op-amps and comparator to settle before the shut-down circuit is released,
thereby preventing speaker pops. To aid in system performance evaluation, there are individual jumper options
(JP1 and JP2) on each channel that allow the user to enable or disable each channel independently of the other.
4.7. Performance
The Silicon Labs Class D reference design board was tested for THD + N, SNR, DFD, and IFD with an Audio
Precision analyzer. During these tests, the main power (the ±50 V supplies) used a TR180 from Hypex electronics
(a low-noise supply) to maximize the amplifier's measured performance. Refer to “AN542: Performance
Improvements in Class D Audio Amplifiers using Si824x Audio Drivers” for additional information concerning the
amplifier's noise and efficiency performance and a more in-depth discussion concerning the amplifier's
architectural design. Please visit www.silabs.com/audio.
+
-
C1
R2
R4
R3
Si8410
Digital Isolator
R5
R1
RSENSE
GND2
GND2
GND1
A1
VDD1
VDD1
To High Side
MOSFET
VDD2
B1
5V
SHUTDOWN
D1
50V