The leading edge blanking time has been set so that current spikes caused by primary-side capacitances and secondary-side rectifier reverse recovery time will not cause premature termination of the switching pulse. The current limit can be lower for a short period after the leading edge blanking time as shown in Figure To avoid triggering the current limit in normal operation, the drain current waveform should stay within the envelope shown. V C regulation changes from shunt mode to the hysteretic auto-restart mode described above. When the fault condition is removed, the power supply output becomes regulated, V C regulation returns to shunt mode, and normal operation of the power supply resumes. Activating the power-up reset circuit by removing and restoring input power or momentarily pulling the CONTROL pin below the power-up reset threshold resets the latch and allows TOPSwitch to resume normal power supply operation.
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This brings TOPSwitch technology advantages to many new applications, i. TV, Monitor, Audio amplifiers, etc. Many significant circuit enhancements that reduce the sensitivity to board layout and line transients now make the design even easier. The internal lead frame of this package uses six of its pins to transfer heat from the chip directly to the board, eliminating the cost of a heat sink.
Package Outline: 3. Soldered to 1 sq. PMAX is the maximum practical continuous power output level for conditions shown. The continuous power capability in a given application depends on thermal environment, transformer design, efficiency required, minimum specified input voltage, input storage capacitance, etc. Provides internal bias current during start-up operation via an internal switched highvoltage current source.
Internal current sense point. Internal shunt regulator connection to provide internal bias current during normal operation. Primary side circuit common and reference point. High efficiency is achieved through the use of CMOS and integration of the maximum number of functions possible.
CMOS process significantly reduces bias currents as compared to bipolar or discrete solutions. Refer to Figure 2 for a block diagram and to Figure 6 for timing and voltage waveforms of the TOPSwitch integrated circuit. Figure 4. Figure 5. Start-up Waveforms for a Normal Operation and b Auto-restart.
TOP223Y Power Integrations, TOP223Y Datasheet