IK3401 Ver la hoja de datos (PDF) - IK Semicon Co., Ltd
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IK3401 Datasheet PDF : 11 Pages
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TECHNICAL DATA
Constant Output Power Limit
When the SENSE voltage, across the
sense resistor Rs, reaches the threshold
voltage, around 0.85V, the output GATE
drive will be turned off after a small delay tpd.
This delay will introduce an additional current
proportional to tpd*Vin/Lp. Since the delay is
nearly constant regardless of the input
voltage Vin . Higher input voltage will result in
a larger additional current and hence the
output power limit is also higher than under
low input line voltage. To compensate this
variation for wide AC input range, a saw-
tooth power-limiter is designed to solve the
unequal power-limit problem. The power
limiter is designed as positive ramp signal
and is fed to the inverting input of the OCP
comparator. This results in a lower current
limit at high-line inouts than at low-line inputs.
VDD Over-voltage Protection
VDD over-voltage protection has been
built in to prevent damage voltage conditions.
When the voltage VDD exceeds the internal
threshold due to abnormal conditions, PWM
output wil be latched off. Over-voltage
conditions are usually caused by open
feedback loops.
Limited Power Control
The FB voltage will increase every time
the output of the power supply is shorted or
over-loaded. If the FB voltage remains higher
than a built-in threshold for longer than td-olp,
PWM output will then be turned off. As PWM
output is turned off, the supply voltage VDD
will also begin decreasing.
When VDD goes below the turn-off
threshold (eg, 10.5V) the controller will be
totally shut down. VDD will be charged up to
the turn-on threshold voltage of 16.5V
through the start-up resistor until PWM
output is restarted. This protection feature
will continue to be activated as long as the
over-loading condition persists. This will
prevent the power supply from overheating
due to over loading conditions.
Protection Latch Circuit
For the IK3401 family, the built-in latch
function provides a versatile protection
feature that does not require external
components. To reset the latch circuit, it is
necessary to disconnect the AC line voltage
of the power supply.
Over Temperature Protection
IK3401 has internal function of over
temperature protection.
Noise Immunity
Noise from the current sense or the
control signal may cause significant puls
width jitter, particulary in continuous-
conduction mode. Slope compensation helps
alleviate this problem. Good placement and
layout practices should be followed. The
designer should avoiding long PCB traces
and component leads. Compensation and
filter components should be located near the
IK3401. Finally, increasing the power-MOS
gate resistance is advised.
Rev 00
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