GS61004B-EVBCD
GaN E-HEMT Full Bridge Evaluation Board
User’s Guide
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GS61004B-EVBCD Rev 200106
© 2020 GaN Systems Inc.
www.gansystems.com 24
Please refer to the Evaluation Board/Kit Important Notice on page 27
Guidelines for Half-Bridge Stereo Audio Operation
This Full Bridge design can be operated as two independent half-bridges by performing the following
simple modifications:
1)
Remove C20, C21 and R29.
2)
Fit a pair of 63V or greater 0.22
F film capacitors to positions C32 and C33. These are essential
to form the output low pass filters with L2 and L1, respectively in the absence of C20.
3)
Remove any jumper links from J200 and J3, as these would otherwise drive the two half bridges
simultaneously, whether in or out of phase. Unless that is still desirable, these jumpers will need
to be removed and the incoming PWM signals instead applied directly to TP1 and TP2, for
example as a Stereo pair of Left and Right channels. D1 and D2 still protect the PE29102 inputs
that are connected. Do not use the coax socket at J100/ 101, as U9 and U5 are now redundant. Pull
down resistors to ground may be required from TP1 and TP2 and if so, these should be 10k.
4)
To avoid using the common output J8, use TP3 and TP4 for one channel and TP6 and TP7 for the
other, which will be less confusing.
Notes
:
For an adequate low frequency response, a large electrolytic capacitor (of at least 63V working
voltage and a value of at least 2200
F or higher MUST be fitted in series with both TP3 and
TP6 or socket J8: each positive capacitor terminal should go to these, respectively. Failing to
observe this required DC blocking will result in damage to your loudspeakers.
The loudspeakers must be connected after the DC blocking electrolytic capacitors, then to
ground: that is, there must be no DC voltage present across the loudspeaker voice coils.
The negative capacitor terminals should go to the + speaker connections, with the – speaker
connections both going to Ground, preferably starred from Pin 1 J7, the DC power inlet ground
terminal.
