Datasheet LYTSwitch-6 (Power Integrations) - 5

LYTSwitch-6
The second was included to ensure that if communication is lost, the primary tries to restart again. Although this should never be the case in normal operation, this can be useful in the case of system ESD P: Primary Chip events for example where a loss of communication due to noise S: Secondary Chip Start disturbing the secondary control er, the issue is resolved when the P: Powered Up, Switching S: Powering Up primary restarts after an auto-restart off time. The auto-restart is reset as soon as an AC reset occurs.
SOA Protection
P: Auto-Restart S: Powering Up In the event there are two consecutive cycles where the ILIM is reached within the blanking time and current limit delay time (including leading edge current spike ~500 ns), the control er will skip tAR(OFF) approximately 2.5 cycles or ~25 ms (based on full frequency of 100 kHz). This provides sufficient time for reset of the transformer S: Has powered No P: Goes to Auto-Restart Off during start-up into large capacitive loads without extending the up within tAR S: Bypass Discharging start-up time.
Input Line Voltage Monitoring
Yes The INPUT OVERVOLTAGE pin is used for input overvoltage sensing tAR and protection. P: Switching S: Sends Handshaking Pulses A sense resistor is tied between the high-voltage DC bulk capacitor after the bridge (or to the AC side of the bridge rectifier for fast AC reset) and the INPUT OVERVOLTAGE pin to enable this functionality. This pin functionality can be disabled by shorting INPUT P: Has Received No P: Continuous Switching OVERVOLTAGE pin to primary Source. Handshaking S: Doesn’t Take Control Pulses
Primary/Secondary-Side Handshake
At start-up, the primary-side initial y switches without any feedback Yes information (this is very similar to the operation of a standard TOPSwitch™, TinySwitch™ or LinkSwitch™ control ers). P: Stops Switching, Hands Over Control to Secondary If no feedback signals are received during the auto-restart on-time (t ), the primary goes into auto-restart mode. Under normal AR conditions, the secondary control er will power-up via the FORWARD pin or from OUTPUT VOLTAGE pin and take over control. From this S: Has Taken No point onwards the secondary controls switching. P: Not Switching Control? S: Doesn’t Take Control If the primary stops switching or does not respond to cycle requests from the secondary during normal operation (when the secondary Yes has control), the handshake protocol is initiated to ensure that the secondary is ready to assume control once the primary begins to End of Handshaking, switch again. An additional handshake is also triggered if the Secondary Control Mode secondary detects that the primary is providing more cycles than were requested. PI-8876-110818 The most likely event that could require an additional handshake is Figure 7. Primary-Secondary Handshake Flow Chart. when the primary stops switching as the result of a momentary line brown-out event. When the primary resumes operation, it will default into a start-up condition and attempt to detect handshake pulses This protection mode also prevents an output overvoltage condition from the secondary. in the event that the primary is reset while the secondary is still in If the secondary does not detect that the primary responds to control. switching requests for 8 consecutive cycles, or if the secondary
Wait and Listen
detects that the primary is switching without cycle requests for 4 When the primary resumes switching after initial power-up recovery or more consecutive cycles, the secondary control er will initiate a from input line voltage fault or an auto-restart event, it will assume second handshake sequence. This provides additional protection control and require a successful handshake to relinquish control to against cross-conduction of SF FET while the primary is switching. the secondary control er.
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Rev. G 08/19 www.power.com Document Outline Product Highlights Description Output Power Table LYTSwitch-6 Functional Description Primary Controller Secondary Controller Absolute Maximum Ratings Thermal Resistance Key Electrical Characteristics Typical Performance Curves InSOP-24D Package Drawing MSL Table ESD and Latch-Up Table Part Ordering Information