an8032 Panasonic Corporation of North America, an8032 Datasheet - Page 9

• Manufacturer Part Number: an8032
• Description: Active Filter Control Ic
• Manufacturer: Panasonic Corporation of North America

Voltage Regulators
[2] Operation descriptions (continued)
1. Normal control (continued)
Application Notes (continued)
2) Control outline description (Refer to figure 2 and figure 3.) (continued)
3) Description of each function
<Summary>
(8) Switching device turn-on
(9) Continuation of operation
(1) V
When the excitation energy of inductor is lost and the free resonance is started, the switching device turns on.
The switching device will turn off when the following two elements cross each other: The product of the input
voltage (E
The fluctuation of input voltage and load current is controlled by changing the peak value height of switching
device current.
The purposes of mixing two signals by using the multiplier are:
Function
MOSFET at the next cycle.
Method
It is difficult from the view point of withstanding voltage to input this voltage directly to the IC. For this
reason, it is input to the V
Function of upper limit voltage clamper
case of monolithic IC, malfunction (such as latch-up) occurs when the terminal voltage decreases to a value
below -V
IC inside
V
tion, this function precedes the former.
B
it swings from high to low.
repeated.
V
terminal voltage is under the threshold value, the power MOSFET is turned on.
B
It detects the discharge of the excitation energy of the inductor (reset operation) and turns on the power
When the inductor is reset, the sub-coil provided on the inductor (bias winding) starts free resonance.
It prevents the damage when the V
Function of lower limit voltage clamper
It prevents the malfunction when the V
The V
However, if the off signal has been given to the power MOSFET by the overvoltage protection func-
B
By resonance, the turn-on signal is sent to the switching device, timed with the sub-coil voltage when
When the switching device is turned on, current flows in the inductor so that the above operation is
to stabilize the control system
to reduce the number of components required
terminal input voltage
Power MOSFET
IN
) and output one (E
BE
(1.5 V typ.)
B
terminal voltage is input to the comparator with hysteresis inside the IC. For this reason, if the
and the parasitic device is activated.
V
BTH
B
terminal through resistor.
Figure
OUT
) of the chopper circuit, and the switching device current.
0 V
4. V
B
terminal voltage exceeds the withstanding voltage.
OFF
B
B
terminal description
terminal voltage swings to negative voltage: generally, in the
ON
OFF
AN8032
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