an8032 Panasonic Corporation of North America, an8032 Datasheet - Page 8

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

AN8032
8
[2] Operation descriptions (continued)
Input voltage
1. Normal control (continued)
monitor
Application Notes (continued)
E
2) Control outline description (Refer to figure 2 and figure 3.) (continued)
IN
(4) Switching device current
(5) Switching device turn-off
(6) Output current supply
(7) Transformer reset signal (V
MPI 2
(power MOSFET) is detected at the CS terminal. (for the above resistor, low resistance value is selected,
considering the power dissipation).
comparator. When the former value becomes larger than the latter one, the current detection comparator
sends the reset signal to the RS latch circuit to turn off the switching device.
is turned-on with inertia current of inductor, and supplies a current to the output of chopper circuit
(E
the transformer starts resonance with the frequency which depends on parasitic capacitance of the board
or parts and inductance of the inductor. This operation is detected at the V
the transformer.
OUT
The voltage generated in the current detection resistor which is connected to the switching device
The CS terminal voltage and the multiplier output voltage are compared by the current detection
When the switching device is turned off, the current flowing in the transformer is cut off. The diode
When the excitation energy has been discharged and the inertia current of the inductor has been lost,
One shot
).
Timer
Current detection
comparator
2.5 V
Figure 3. Explanation of block diagram and normal operation
Turn-on signal
Multiplier
V
2.5 V
BTH
V
Latch circuit
REF
B
Lower limit
voltage clamp
) detection
Overvoltage detection
Error amp.
Upper limit
voltage clamp
Low voltage
protection
Drive
10 V/8 V
2.5 V
2.6 V
9
6
8
5
1
4
V
V
V
OVP
CS
EI
CC
B
OUT
Power MOSFET
Turn-off signal
Power MOS
B
On
Voltage Regulators
terminal through sub-coil of
Current detection
resistor
SBD
Power MOS
Off
E
OUT