Datasheet MIN1072M MinE-CAP (Power Integrations) - 7

MinE-CAP
auxiliary winding is rectified using diode D4 and filtered by capacitor Y capacitor connecting the input DC bulk voltage to the secondary C15. An RC snubber can be placed across D4 to suppress voltage ground node by shunting noise current back to the primary ground. spikes, if necessary. Since the output voltage of the charger varies from 5 V to 20 V, the output of the auxiliary winding also varies and
MinE-CAP IC and InnoSwitch3-Pro IC Primary Components
depending on the secondary to auxiliary turns ratio as well as the
Selection
coupling coefficient between the primary and auxiliary. A linear The fol owing section focuses on the selection of the MinE-CAP IC regulator comprising resistors R17 and R18, Zener diode D6, and specific components as well as adjustments to the auxiliary bias transistor Q4 provides a relatively stable DC voltage based on the circuit to accommodate the bias requirements of the InnoSwitch3-Pro breakdown voltage of D6 at the emitter terminal of Q4. Bias current IC and the MinE-CAP IC. For a comprehensive guide to InnoSwitch3-Pro can then be control ed using resistor R19. component selection, see the InnoSwitch3-Pro data sheet. Zener diode D5 offers primary sensed overvoltage protection. In The resistor V of the MinE-CAP IC corresponding to the series TOP case of overvoltage at the output of the converter, the auxiliary resistors R3 and R5 in the schematic in Figure 8, serves the dual winding voltage also increases until D5 breaks down, causing excess purpose of al owing input line monitoring capabilities for the current to flow into the BPP pin of the InnoSwitch3 IC. If the current InnoSwitch3-Pro IC and regulating the voltage of the low-voltage flowing into the BPP pin exceeds the I threshold, the InnoSwitch3 input bulk capacitor, C . The InnoSwitch3-Pro data sheet recommends SD LV control er latches off to prevent any further increase in output a total value of 3.8 MW for R3 and R5 for universal line input OV/UV voltage. Resistor R20 limits the current injected to the BPP pin during protection. Using this value for the R resistor programs the TOP an overvoltage event. MinE-CAP IC to keep the voltage across C to approximately 140 V, LV which is well within the 160 V rating of the capacitor. Use resistors InnoSwitch3-Pro Secondary and USB Power Delivery and Transformer with a tolerance of 1% or better for tighter regulation of the C design shall be in consideration of the AC-DC control er used LV voltage. See InnoSwitch3-Pro data sheet for secondary-side component The recommended value for R (R1 in the schematic) is 1.0 MW for descriptions. BOT accurate sensing of the MinE-CAP negative terminal of C . The LV
Key Application Considerations
voltage regulation of C is also sensitive to the value of R . A LV BOT bleeder resistor, R4, must also be connected in paral el with C to LV
No-Load Consumption
help regulate the voltage across the said capacitor, especial y if V CLV The MinE-CAP IC is designed to only consume around 500 mA of bias goes beyond the voltage set by R . Set the value of the bleeder TOP current from the BYPASS pin, which means the MinE-CAP IC only resistor to 4.0 MW for optimum operation. Resistor values higher adds a few mW to the system no-load input power. For the design in than the recommended might cause overvoltage faults in the Figure 8, the measured maximum no-load consumption was only 56 mW MinE-CAP IC. On the other hand, values that are too low might at VIN = 265 VAC. For minimal no-load consumption while ensuring prevent C from charging to the programmed voltage, especial y LV proper operation of the MinE-CAP IC, fol ow the recommended during trickle charging. resistor values and bias selection method outlined in the “MinE-CAP During normal operation, the MinE-CAP IC and InnoSwitch3-Pro IC and InnoSwitch3-Pro Primary Components Selection” section of this both source their bias currents from the auxiliary winding through the application example. linear regulator shown in Figure 8. Therefore, the selection of current
Critical Components Selection
limiting resistor R14 must take into account the bias requirements of both ICs (I , + I ). For the circuit in Figure 8, R19 can S1 MinE-CAP S2, InnoSwitch3
Input Capacitors
be computed using the fol owing equation: The value of the input capacitors can be determined based on the Capacitance vs. Output Power curve shown in Figure 2. For an V ̶ (V + V ) BR(D4) BE(Q1) BPP(SHUNT) output power of 65 W, the nominal capacitance for the high-voltage R19 = I + I capacitor, C , should be 30 mF while the low-voltage capacitor, C , S1(MinE-CAP) S2(INNOSWITCH) HV LV should be around 90 mF. Both capacitors are mounted with their axial V , D6 = breakdown voltage of Zener D4 lines paral el to the PCB; thus, both capacitors must have a maximum BR V = Base-Emitter Voltage of Q1 diameter of 10 mm to fit the 12 mm height requirement of the design. BE(Q1) V = 5.6 V (see InnoSwitch3 data sheet) The remaining 2 mm clearance is for the instal ation of a heat BPP(Shunt) I = Typical MinE-CAP bas current spreader with insulation as well as to account for enclosure S1(MinE-CAP) I = InnoSwitch3 bias current tolerances. Using the above requirements and after a few test S2(InnoSwitch3) iterations and based on component availability, the final input Note that the computed resistance for R19 is just a starting-point capacitor specifications are as fol ows: value and can be adjusted to optimize performance, especial y for 1. HV Capacitor: 39 mF, 400 V , 10 mm(D) x 37 mm(L) no-load power reduction. Also, the formula given above is only valid DC 2. LV Capacitor: 100 mF, 160 V , 8 mm(D) x 42.5 mm(L) for the regulator topology used in Figure 8. DC For a more detailed and general approach to the selection of the The InnoSwitch3-Pro IC uses the bypass capacitor connected to the input capacitors, check the MinE-CAP Application Note. BPP pin (C16 in Figure 8) to set the current limit setting for the design. If the MinE-CAP IC is placed close to the InnoSwitch3 IC,
EMI Filter
both ICs could share the same bypass capacitor. However, if the The EMI filter in this design uses a T-Filter topology comprising a MinE-CAP BYPASS pin is connected to the InnoSwitch3 BPP pin couple of common-mode chokes and a single X-capacitor, as shown in through a long trace or a via, an extra bypass capacitor should be Figure 8. Both L1 and L2 use an HF60 Mn-Zn Toroid. Common mode placed as close as possible to the MinE-CAP IC and must be choke L1 is 220 mH, while L2 is 18 mH. C1 is a 220 nF Class-X Film connected to the BYPASS and GROUND pins using very short traces. Capacitor. The common-mode chokes suppress common mode noise If an extra bypass capacitor is used, a 10 nF to 100 nF, 10 V X7R while the leakage inductance from both chokes combined with C1, ceramic capacitor is recommended. Avoid using capacitance values and the input bulk capacitors form an LC-filter for differential mode higher than 100 nF when using standard current limits for the noise attenuation. Common mode noise is further reduced by the InnoSwitch3-Pro (see InnoSwitch3-Pro BPP capacitor tolerance limits).
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