Datasheet MIN1072M MinE-CAP (Power Integrations) - 10

MinE-CAP EMI Considerations
For the design in Figure 11, in place of the single high-voltage When the MinE-CAP disconnects the low-voltage capacitor, C from capacitor, two high-voltage capacitors must be chosen such that its LV the circuit during high-line operation, the conducted EMI may increase. impedance is not too high when evaluated at the maximum switching For designs that utilize the EMI filter topology shown in Figure 10, frequency of the converter. In general, the output impedance of the removal of the low-voltage capacitor (C3) fundamental y shifts the filter must be less than 10% of the impedance of the converter at full cut-off of the low-pass filter formed by the leakage inductances of the load. Final y, the low-voltage capacitor (C3) must be placed after the common-mode chokes (L1 and L2), X-capacitor (C1), and the input inductor, L3. This way, current from the low-voltage capacitor is not bulk capacitors to a higher frequency. Removal of the low-voltage hindered by the impedance of L3 when operating at low-line. capacitor also increases the total input bulk capacitor ESR. These
Quick Design Checklist
may result in an increase in differential-mode noise at high-line. Aside from the verification of the functionality of the InnoSwitch3-Pro IC, proper operation of the MinE-CAP IC must also be checked. At
VBULK
the minimum, the fol owing verification tests must be performed.
L
1. V Regulation – Check that the maximum voltage across the + + CLV L1 L2 C3 low-voltage capacitor never exceeds the capacitor’s voltage
AC
+ C1 C2 rating. Perform this test across the whole input voltage and
IN
MinE-CAP output power range. Checking V regulation during brown-in Switch CLV and brown-out is also recommended.
N
2. Ensure that all resistors do not go beyond their voltage ratings. PI-9218-082120 For R and R , a single 1206 chip resistor will suffice. For BOT BLEED R , the use of two 1206 chip resistors in series is recommended. TOP Figure 10. T-Filter EMI Filter Topology. 3. The MinE-CAP IC must seamlessly transition from high-line to low-line operation and vice-versa without causing the This effect can be remedied by either increasing the leakage InnoSwitch3-Pro IC to enter auto-restart mode. Verify this across inductances of the common-mode chokes or by increasing the value al loading conditions. of C1. Such a solution may not be viable due to several restrictions, such as size or excessively high inductance requirements. The filter 4. Thermal Check – Verify that the MinE-CAP IC does not cause an in Figure 11 is still a viable topology to use. However, the computation OTP fault when operating at maximum load throughout the whole of the required values of C1, L1, and L2 must take into account the input range. If the unit is a charger, perform the thermal check removal of C3 in the design. with the enclosure instal ed. An alternative approach is to use a Pi-filter to help suppress differential-mode noise. The schematic for this alternative design is shown in Figure 11. L3
V BULK L
+ + L1 L2 C3
AC
+ + C1 C2 C4
IN
MinE-CAP Switch
N
PI-9219-082120 Figure 11. Typical EMI Filter with a Pi-Filter at the Rectified Side. A dedicated differential choke enables the use of a smal er common mode choke. The 400 V capacitance is then split into two half size capacitors either side of this differential choke in a pi-filter configuration.
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Rev. D 11/20 www.power.com