PKS607F 查看數據表（PDF） - Power Integrations, Inc

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PKS607F

PeakSwitch Family Enhanced, Energy-Efficient, Off-Line Switcher IC With Super Peak Power Performance

Power Integrations, Inc 

300

200

100

0

10

5

0

VDRAIN

VDC-OUTPUT

0

5

10

Time (s)

Figure 6. PeakSwitch Auto-Restart Operation.

(IEN <25 µA). Then the internal auto-restart latch is reset and

the power MOSFET switching will resume once the AC input

voltage is applied again (IEN >25 µA). This effectively provides

a latching shutdown function with AC reset during such a fault

condition.

When a brownout or line sag occurs, output regulation may

be lost and the EN/UV pin will receive no feedback (it is

pulled low). After 30 ms of no feedback, MOSFET switching

is disabled. Since the AC line is abnormally low (IEN <25 mA)

MOSFET switching remains disabled until normal line voltage

is restored. The power MOSFET switching will resume once

the AC input returns to normal (IEN >25 µA). This effectively

disables the latching shutdown function during such a condition.

Auto-Restart (UV resistor not present)

In the event of a fault condition such as output overload,

output short circuit or an open loop condition, PeakSwitch

enters into auto-restart operation. An internal counter

clocked by the oscillator is reset every time the EN/UV pin

is pulled low. When the EN/UV pin receives no feedback

for 30 ms, the power MOSFET switching is disabled for

5 seconds (150 ms for the first auto-restart event). The

auto-restart alternately enables and disables the switching

of the power MOSFET until the fault condition is removed.

Figure 6 illustrates auto-restart circuit operation in the presence

of an output short circuit.

Adaptive Switching Cycle On-time Extension

Adaptive switching cycle on-time extension keeps the MOSFET

on until current limit is reached, instead of terminating after

the DCMAX signal goes low. This on-time extension is adaptive

because it only occurs after the ENABLE pin has been high

for approximately 750 µs, a condition that would arise if the

peak output power was required in low line conditions. On-time

extension is disabled during the startup of the power supply.

PKS603-607

PeakSwitch Operation

PeakSwitch devices operate in the current-limit mode. When

enabled, the oscillator turns the power MOSFET on at the

beginning of each cycle. The MOSFET is turned off when the

current ramps up to the current limit or when the DCMAX limit

is reached. Since the highest current limit level and frequency

of a PeakSwitch design are constant, the power delivered

to the load is proportional to the primary inductance of the

transformer and peak primary current squared. Hence, designing

VEN

CLOCK

DMAX

IDRAIN

VDRAIN

PI-2749-050301

Figure 7. PeakSwitch Operation at Near Maximum Loading.

VEN

CLOCK

DMAX

IDRAIN

VDRAIN

PI-2667-090700

Figure 8. PeakSwitch Operation at Moderately Heavy Loading.

5

Rev. I 02/07

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