Datasheet InnoSwitch3-MX (Power Integrations) - 5

InnoSwitch3-MX
1.05 At power-up, after the primary bypass capacitor is charged and the I state is latched, and prior to switching, the state of the UNDER/ LIM OVER INPUT VOLTAGE pin is checked to confirm that it is above the
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1.0 brown-in and below the overvoltage shutdown thresholds. -8205-120516
(A
PI 0.95 In normal operation, if the UNDER/OVER INPUT VOLTAGE pin current
LIM
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 0.9 UV- resume once the UNDER/OVER INPUT VOLTAGE pin current is above the brown-in threshold. 0.85
ormalized I
In the event that the UNDER/OVER INPUT VOLTAGE pin current is
N
above the overvoltage threshold, the control er will also enter 0.8 auto-restart. Again, switching will only resume once the UNDER/ OVER INPUT VOLTAGE pin current has returned to within its normal 0.75 operating range. 30 40 50 60 70 80 90 100 The input line UV/OV function makes use of an internal high-voltage
Steady-State Switching Frequency (kHz)
MOSFET on the UNDER/OVER INPUT VOLTAGE pin (V ) to reduce V power consumption. The control er samples the input line at light Figure 6. Normalized Primary Current vs. Frequency Jitter. load conditions when the time between switching cycles is 50 µs or more. At <50 µs between switching cycles, the high-voltage MOSFET In auto-restart, switching of the power MOSFET is disabled for t . will remain on making sensing continuous. AR(OFF) There are 2 ways to enter auto-restart:
Primary-Secondary Handshake
1. Continuous secondary requests at above the overload detection At start-up, the primary-side initial y switches without any feedback frequency (~110 kHz) for longer than 82 ms (t ). information (this is very similar to the operation of a standard AR 2. No requests for switching cycles from the secondary for >t . TOPSwitch™, TinySwitch™, LinkSwitch™ and other InnoSwitch3™ AR(SK) controllers). The InnoMux could initiate an auto-restart by no longer sending request cycles to the InnoMux3-MX secondary control er. The If no feedback signals are received during the auto-restart time (t ), AR primary control er will then restart. the primary goes into auto-restart mode. Under normal conditions, the InnoMux control er will power-up from the output voltage within It is also possible that communication is lost, in which case the the auto-restart time and will then provide power to the secondary primary will also try to restart. Although this should never be the control er in the InnoSwitch3-MX. The InnoMux will then direct case in normal operation, it can be useful when system ESD events InnoSwitch3 MX secondary to take over control. From this point (for example) cause a loss of communication due to noise disturbing onwards the secondary controls switching. the secondary control er. The issue is resolved when the primary restarts after an auto-restart off-time. If the primary control er stops switching or does not respond to cycle requests from the secondary during normal operation (when the The first auto-restart off-time is short (t ). This short auto- secondary has control), the handshake protocol is initiated to ensure AR(OFF)SH restart time is to provide quick recovery under fast reset conditions. that the secondary is ready to assume control once the primary The short auto-restart off-time al ows the control er to quickly check begins to switch again. An additional handshake is also triggered if to determine whether the auto-restart condition is maintained beyond the secondary detects that the primary is providing more cycles than t . were requested. AR(OFF)SH The auto-restart is reset as soon as an AC reset occurs. The most likely event that could require an additional handshake is
SOA Protection
when the primary stops switching as the result of a momentary line In the event that there are two consecutive cycles where the I is brown-out event. When the primary resumes operation, it will default LIM reached within ~500 ns (the blanking time + current limit delay time), to a start-up condition and attempt to detect handshake pulses from the control er will skip 2.5 cycles or ~25 µs (based on full frequency the secondary. of 100 kHz). This provides sufficient time for the transformer to reset If secondary does not detect that the primary responds to switching with large capacitive loads without extending the start-up time. requests, or if the secondary detects that the primary is switching
Input Line Voltage Monitoring
without cycle requests, the secondary control er will initiate a second The UNDER/OVER INPUT VOLTAGE pin is used for input undervoltage handshake sequence. This provides additional protection against and overvoltage sensing and protection. cross conduction of the SR FET while the primary is switching. This protection mode also prevents an output overvoltage condition in the A 4 MΩ resistor is tied between the high-voltage DC bulk capacitor event that the primary is reset while the secondary is still in control. after the bridge (or to the AC side of the bridge rectifier for fast AC reset) and the UNDER/OVER INPUT VOLTAGE pin to enable this
Wait and Listen
functionality. This function can be disabled by shorting the UNDER/ When the primary resumes switching after initial power-up recovery OVER INPUT VOLTAGE pin to primary GND. from an input line voltage fault (UV or OV) or an auto-restart event, it will assume control and require a successful handshake to relinquish control to the secondary control er.
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Rev. B 03/19 www.power.com Document Outline Product Highlights Description Output Power Table Pin Functional Description InnoSwitch3-MX Functional Description Absolute Maximum Ratings Thermal Resistance Key Electrical Characteristics InSOP-24D Package Drawing Part Ordering Information