User guide
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V 1.0.1
2021-01-27
REF-AIRCON-C302A-IM564 user guide
Air conditioner application reference design kits
System design
An 11 MHz rail-to rail I/O CMOS operational amplifiers SGM8968-1 used for PFC current sensing.
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R5 and R60 select the OPA’s bias; a very low bias is recommended (less than 10% of VCC)
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R73 must be equal to parallel value of R5 and R60 to achieve better CMR
-
R43, R58, R52, R59 and C24 build a difference mode LPF; time constant 0.1 ~ 0.5 µs is
recommended
3.3
Auxiliary power supply
Infineon’s latest (5
th
generation) fixed-frequency CoolSET
TM
ICE5AR4770BZS is used for the flyback auxiliary
power controller to 15 V and +7 V. Figure 22 depicts the schematic of the auxiliary power supply for the
REF-AIRCON-C302A-IM564 board. The 15 V and 12 V power supply output ability is 450 mA; for 5 V power supply,
the output ability is 200 mA.
Figure 22
Power supply section of the REF-AIRCON-C302A-IM564 reference design
Please note that IMC302A’s AD sensing reference is VDD, which means VDD’s accurateness can affect the ADC
result. A linear regulator LM7805 (U8) is used for 5 V VDD (from +7 V of flyback output) to make sure IMC302A’s
power is steady and clean. The LM7805’s GND pin should be as close to IMC302A’s GND as possible to reduce
ground noise.
