Datasheet InnoSwitch3-CE (Power Integrations) - 5

InnoSwitch3-CE
The first auto-restart off-time is short (t ). This short auto- AR(OFF)SH restart time is to provide quick recovery under fast reset conditions. The short auto-restart off-time al ows the control er to quickly check to P: Primary Chip determine whether the auto-restart condition is maintained beyond S: Secondary Chip Start t . If so, it will resort to a full auto-restart off-time. P: Powered Up, Switching AR(OFF)SH S: Powering Up The auto-restart is reset as soon as an AC reset occurs.
SOA Protection
In the event that there are two consecutive cycles where the I is LIM P: Auto-Restart reached within ~500 ns (the blanking time + current limit delay time), S: Powering Up the control er will skip 2.5 cycles or ~25 ms (based on full frequency of 100 kHz). This provides sufficient time for the transformer to reset 2s with large capacitive loads without extending the start-up time.
Secondary Rectifier/SR MOSFET Short Protection (SRS)
S: Has powered No P: Goes to Auto-Restart Off In the event that the output diode or SR FET is short-circuited before up within 64 ms? S: Bypass Discharging or during the primary conduction cycle, the drain current (prior to the end of the leading edge blanking time) can be much higher than the Yes maximum current limit threshold. If the control er turns the high- 64 ms voltage power MOSFET off, the resulting peak drain voltage could P: Switching exceed the rated BV of the device, resulting in catastrophic failure S: Sends Handshaking Pulses DSS even with minimum on-time. To address this issue, the control er features a circuit that reacts when the drain current exceeds the maximum current limit threshold prior to the end of leading-edge blanking time. If the leading-edge P: Has Received No P: Continuous Switching Handshaking current exceeds current limit within a cycle (200 ns), the primary S: Doesn’t Take Control Pulses control er will trigger a 30 ms off-time event. SOA mode is triggered if there are two consecutive cycles above current limit within t Yes LES (~500 ns). SRS mode also triggers ~200 ms off-time, if the current limit is reached within 200 ns after a 30 ms off-time. P: Stops Switching, Hands Over Control to Secondary
Input Line Voltage Monitoring
The UNDER/OVER INPUT VOLTAGE pin is used for input undervoltage and overvoltage sensing and protection. A 4 MΩ resistor is tied between the high-voltage DC bulk capacitor S: Has Taken No P: Not Switching after the bridge (or to the AC side of the bridge rectifier for fast AC Control? S: Doesn’t Take Control reset) and the UNDER/OVER INPUT VOLTAGE pin to enable this functionality. This function can be disabled by shorting the UNDER/ Yes OVER INPUT VOLTAGE pin to SOURCE pin. At power-up, after the primary bypass capacitor is charged and the End of Handshaking, ILIM state is latched, and prior to switching, the state of the UNDER/ Secondary Control Mode OVER INPUT VOLTAGE pin is checked to confirm that it is above the PI-7416-102814 brown-in and below the overvoltage shutdown thresholds. Figure 7. Primary-Secondary Handshake Flowchart. In normal operation, if the UNDER/OVER INPUT VOLTAGE pin current fal s below the brown-out threshold and remains below brown-in for longer than t , the control er enters auto-restart. Switching will only
Primary-Secondary Handshake
UV- resume once the UNDER/OVER INPUT VOLTAGE pin current is above At start-up, the primary-side initial y switches without any feedback the brown-in threshold. information (this is very similar to the operation of a standard TOPSwitch™, TinySwitch™ or LinkSwitch™ control ers). In the event that the UNDER/OVER INPUT VOLTAGE pin current is above the overvoltage threshold, the control er will also enter If no feedback signals are received during the auto-restart on-time auto-restart. Again, switching will only resume once the UNDER/ (t ), the primary goes into auto-restart mode. Under normal AR OVER INPUT VOLTAGE pin current has returned to within its normal conditions, the secondary control er will power-up via the FORWARD operating range. pin or from the OUTPUT VOLTAGE pin and take over control. From this point onwards the secondary controls switching. The input line UV/OV function makes use of an internal high-voltage MOSFET on the UNDER/OVER INPUT VOLTAGE pin to reduce power If the primary control er stops switching or does not respond to cycle consumption. If the cycle off-time t is greater than 50 ms, the requests from the secondary during normal operation (when the OFF internal high-voltage MOSFET will disconnect the external 4 MΩ secondary has control), the handshake protocol is initiated to ensure resistor from the internal IC to eliminate current drawn through the that the secondary is ready to assume control once the primary 4 MΩ resistor. The line sensing function will activate again at the begins to switch again. An additional handshake is also triggered if beginning of the next switching cycle. the secondary detects that the primary is providing more cycles than were requested.
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Rev. D 08/18 www.power.com Document Outline Product Highlights Description Output Power Table Pin Functional Description InnoSwitch3-CE Functional Description Primary Controller Secondary Controller Applications Example Key Application Considerations Selection of Components Recommendations for Circuit Board Layout Layout Example Quick Design Checklist Absolute Maximum Ratings Thermal Resistance Key Electrical Characteristics Typical Performance Curves InSOP-24D Package Drawing InSOP-24D Package Marking Part Ordering Table MSL Table ESD and Latch-Up Table Part Ordering Information