Datasheet InnoSwitch3-EP (Power Integrations) - 9

InnoSwitch3-EP Applications Example
C10 470 pF 250 VAC VR2 SMAZ8V2-13-F 8.2 V 2 FL1
12 V, 0.7 A
L2 C21 R25 1 nF 30 Ω C19 10 µH C14 R30 200 V 1/8 W 680 2.2 µF µF 100 Ω R27 16 V 25 V 1/10 W 1.2 MΩ
12 V
1% 1 FL2 C24 1/16 W C4 2.2 nF
RTN
R3 1000 pF R8 Q2 50 V 2 MΩ 630 V 200 kΩ 6 AO4486
5 V, 0.3 A
1% L3 BR1 R24 C22 R29 DF08S 62 Ω 1 nF C18 10 µH 100 Ω R16 800 V D1 1/8 W 200 V 560 µF 1/10 W 133 kΩ R22 DFLR1600-7 6.3 V 1% 68 Ω 600 V C23 1/16 W R4 5 2.2 nF 1.8 MΩ 50 V 1% NC Q1 4 AO6420 C2 C3 3 F1 10 µF 10 µF R13 1 A 400 V 400 V T1 EE1621 33.2 kΩ 1% RT1 R9 1/16 W 10 Ω t
O
47 Ω C12 1/10 W 2.2 µF 25 V C7 D7 2.2 µF
90 - 265
DFLR1200-7 C8 25 V
VAC
330 pF VR1
L N
50 V MMSZ5231B-7-F
S
D3
D V FWD SR VO BP GND
BAV21WS-7-F R12
CONTROL
R26 0.2 Ω
FB
36 Ω 1% R6 1/10 W 6.2 kΩ 1/10 W
S BPP IS InnoSwitch3-EP
C5 C6 U1 L1 22 µF 4.7 µF INN3672C-H602 330 µH 50 V 16 V
RTN
PI-8374-051818 Figure 10. Schematic DER-611, 5 V, 0.3 A and 12 V, 0.7 A for HVAC (Heating, Ventilation and Air-Conditioning) Application. The circuit shown in Figure 10 is a low cost 5 V, 0.3 A and 12 V, 0.7 A transformer is rectified by SR FET Q1 and filtered by capacitor C18. dual output power supply using INN3672C. This dual output design High frequency ringing during switching transients that would features high efficient design satisfying cross regulation requirement otherwise create radiated EMI is reduced via a snubber (resistor R24 without a post-regulator. and capacitor C22). The 12 V secondary of the transformer is rectified Bridge rectifier BR1 rectifies the AC input supply. Capacitors C2 and by SR FET Q2 and filtered by capacitor C19. High frequency ringing C3 provide filtering of the rectified AC input and together with during switching transients that would otherwise create radiated EMI inductor L1 form a pi-filter to attenuate differential mode EMI. is reduced via a snubber (resistor R25 and capacitor C21). Y capacitor C10 connected between the power supply output and Synchronous rectifications (SR) are provided by Switchs Q1 and Q2. input help reduce common mode EMI. Q1 and Q2 are turned on by the secondary-side control er inside IC Thermistor RT1 limits the inrush current when the power supply is U1, based on the winding voltage sensed via resistor R9 and fed into connected to the input AC supply. the FORWARD pin of the IC. Input fuse F1 provides protection against excess input current In continuous conduction mode of operation, the Switch is turned off resulting from catastrophic failure of any of the components in the just prior to the secondary-side’s commanding a new switching cycle power supply. One end of the transformer primary is connected to from the primary. In discontinuous conduction mode of operation, the rectified DC bus; the other is connected to the drain terminal of the power switch is turned off when the voltage drop across the the Switch inside the InnoSwitch3-EP IC (U1). Switch fal s below 0 V. Secondary-side control of the primary-side power switch avoids any possibility of cross conduction of the two A low-cost RCD clamp formed by diode D1, resistors R22, R8, and Switchs and provides extremely reliable synchronous rectification. capacitor C4 limits the peak drain voltage of U1 at the instant of turn-off of the Switch inside U1. The clamp helps to dissipate the The secondary-side of the IC is self-powered from either the energy stored in the leakage reactance of transformer T1. secondary winding forward voltage or the output voltage. Capacitor C7 connected to the SECONDARY BYPASS pin of InnoSwitch3-EP IC The InnoSwitch3-EP IC is self-starting, using an internal high-voltage U1, provides decoupling for the internal circuitry. current source to charge the PRIMARY BYPASS pin capacitor (C6) when AC is first applied. During normal operation the primary-side Total output current is sensed by R12 between the IS and GROUND block is powered from an auxiliary winding on the transformer T1. pins with a threshold of approximately 35 mV to reduce losses. Once Output of the auxiliary (or bias) winding is rectified using diode D7 the current sense threshold is exceeded the device adjusts the and filtered using capacitor C5. Resistor R6 limits the current being number of switch pulses to maintain a fixed output current. supplied to the PRIMARY BYPASS pin of InnoSwitch3-EP IC (U1). The The output voltages are sensed via resistor divider R13, R16, and latch-off/auto-restart primary-side overvoltage protection is obtained R27, and output voltages are regulated so as to achieve a voltage of using Zener diode VR1 with current limiting resistor R26. 1.265 V on the FEEDBACK pin. The 12 V phase boost circuit, R30 and The secondary-side control er of the InnoSwitch3-EP IC provides C24, in paral el with 12 V feedback resistor, R27, and 5 V phase boost output voltage sensing, output current sensing and drive to a Switch circuit, R29 and C23, in paral el with 5 V feedback resistor, R16, providing synchronous rectification. The 5 V secondary of the
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Rev. G 07/19 www.power.com Document Outline Product Highlights Description Output Power Table Pin Functional Description InnoSwitch3-EP Functional Description Primary Controller Secondary Controller Applications Example Key Application Considerations Selection of Components Components for InnoSwitch3-EP Primary-Side Circuit Components for InnoSwitch3-EP Secondary-Side Circuit Recommendations for Circuit Board Layout Layout Example Quick Design Checklist Absolute Maximum Ratings Thermal Resistance Typical Performance Curves InSOP-24D Package Drawing InSOP-24D Package Marking Part Ordering Table MSL Table ESD and Latch-Up Table Part Ordering Information