Datasheet MIN1072M MinE-CAP (Power Integrations) - 4

MinE-CAP MinE-CAP Functional Description
The MinE-CAP IC comprises a digital control er and high-voltage
VCLV
power switch which connected in series with a low-voltage (160 V) bulk electrolytic capacitor in a power converter. The MinE-CAP IC connects this low-voltage capacitor into the power supply at low input line voltage conditions and disconnects it at high input line voltages. A high-voltage (400 V) capacitor is connected in paral el to support power delivery in high line conditions. The effective input capacitance is equivalent the sum of C and C at low input line to maintain the
IDS
LV HV same minimum DC voltage to the DC/DC converter stage. At high input line condition the switch is disabled to ensure the voltage across C does not exceeded the rated voltage of the capacitor. LV The MinE-CAP IC also includes a control signal transmitted from the MinE-CAP LINE pin to control the start-up and fault shutdown of an InnoSwitch IC via its V pin. Figure 4 il ustrates the high level block
VCLV
diagram.
Start-Up Inrush Management
Upon application of AC input, the MinE-CAP control er is in the off-
IDS
state and the power switch is open. The C is not engaged in the LV circuit and only C is charged by the AC input. C is significantly PI-9217-082520 HV HV smal er than C and the inrush stress on the bridge rectifier and fuse LV is therefore greatly reduced. The MinE-CAP IC then performs control ed charging of C as described in the next section. This Figure 6. Charging Algorithm used for Low-Line Start-Up. LV control ed charging of the C al ows MinE-CAP designs to eliminate LV the inrush NTC, improving the overall system design by removing a In high-line start-up condition (V > 150 VAC), the active charging IN thermal hotspot and increases conversion efficiency. algorithm of C described above is not employed. When selected LV according to Figure 2, C alone can deliver full power converter HV
Power-Up
output power at line voltages above 150 VAC. The InnoSwitch power The MinE-CAP Bypass is derived external y through direct connection control IC is therefore enabled immediately using the V pin output with the InnoSwitch BPP pin. Note that during this time, the signal while C is trickle charged at a lower rate until the steady-state LV InnoSwitch IC is disabled from delivering power since the current C voltage is reached. The voltage across C is subsequently LV LV received by the InnoSwitch V pin is I which is below brown-in precisely monitored and recharged as required depending on input INJECT(UV) threshold of InnoSwitch (further details on V pin operation available line conditions. in InnoSwitch data sheets).
Steady-State Active Charging Power Switch Control Logic
Once the BYPASS (BP) pin reaches regulation the MinE-CAP control er The resistor connected to the VTOP pin is used to sense the line waits for the bulk voltage to be above the MinE-CAP brown-in voltage. During normal operation the MinE-CAP IC is fully on while threshold (I ) measured on the VTOP pin. After brown-in, the UV+ the bulk voltage remains below the user defined threshold (V ). control er enters a wait state for 20 ms to ensure power supply input COV+ voltage levels have stabilized. After that time, the MinE-CAP IC V = I × R COV± COV± TOP samples the bulk DC voltage to determine which of two possible C LV where charge up schemes to adopt as described below. I = I - I In low-line start-up conditions (V < 150 VAC), the MinE-CAP IC COV- COV+ COV(H) IN performs precisely control ed active charging of C . At low-line LV start-up condition, it is important to pre-charge C to support full In this condition C contributes to the output power delivery. Once LV LV power capability prior to enabling the InnoSwitch. The MinE-CAP IC the bulk voltage reaches V , the MinE-CAP IC is turned off to COV+ controls the internal high-voltage switch as a current source and uses maintain C below its rated voltage. In this state, only C is LV HV a precise constant current, pulse charging of C , see Figure 6. This contributing to output power delivery. LV algorithm al ows fast charging of C and ensures PSU is able to The MinE-CAP IC measures the VBOT pin voltage to determine if LV deliver full power in less than 250 ms from initial AC line connection. voltage on C and C are equal. Once the DC bus voltage fal s LV HV below V and if the MinE-CAP IC determines C and C voltages COV- LV HV are equal (VBOT pin voltage close to 0 V), the MinE-CAP power switch is turned on and C is reengaged as an energy source for the LV power converter. As such, the MinE-CAP IC is designed to turn on and off, engaging and disengaging C during each AC line cycle, as may be required at LV intermediate AC line voltages. Figure 7 summarizes the steady-state control of the MinE-CAP power switch.
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Rev. D 11/20 www.power.com