Calyx S1A0071 - Audio Processor for Class-D Power AMP - Manual (Page 19)

S1A0071 Audio Processor for Class-D Power AMP
Digital & Analog Co., Ltd. (Rev. 1.0) -19-
(This value is obtained by dividing MOSFET power supply voltage with Rx and Ry. Considering the
speaker load resistance and power supply impedance, Vls (soft clipping level) is generated. So,
VLN/VLP accepts this value, and then stable operation is expected.)
To decide on the actually appropriate Vls, you must monitor the output waveform at the set connected
to the power supply. You can set Rx and Ry to values that will make VLP and VLN generate maximum
waveforms, respectively; within the range that has no clipping distortion and other noises. If you don't
want to operate the soft clipping function, connect VLN and VLP pins to VCC and VSS.
※ Other Application information
♦ PROTECTION
S1A0071 has built-in Output DC Short Protection, and Over Current Protection. When the
protection block output pins are shorted to VCCP or GND or VSSP, respectively, the internal
detect circuit immediately stops the buffer output.
The Over Current Detect function is driven by the Current Sensing resistor (50m ), which
indicates an over current if the resistor develops a potential of about 1.0V. Then the current is
about 1.0(V) / 0.05 ( ) = 20 (A). If the speaker " -" pin becomes VCCP or VSSP and DC shorted,
the sensing resistor will be destroyed as well as S1A0071. To prevent IC destruction, you can
insert resistors of few k in series at the CF1 pins (Pin28, 45). (Please refer to No te 5 for more
details on protection return time)
♦ FET DRIVER
S1A0071 produces an output of 4.5Vp-p and low level is VSS. Any GATE BUFFER ICs can satisfy
these conditions, but they should be designed as FAIR to optimally use with S1A0051, a MOSFET
DRIVER