an8029 Panasonic Corporation of North America, an8029 Datasheet - Page 11

• Manufacturer Part Number: an8029
• Description: Self-excited Rcc Pseudo-resonance Type Ac-dc Switching Power Supply Control Ic
• Manufacturer: Panasonic Corporation of North America

Voltage Regulators
[1] Operation descriptions (continued)
8. Timer latch (continued)
9. Output block
Application Notes (continued)
Power supply
output voltage
Power MOSFET
current
TIM/OVP
terminal voltage
(push-pull) type output circuit which performs the sink and source of the current with the NPN transistor as shown
in figure 10.
provided with the sink capability even if the supply voltage V
power MOSFET without fail.
Because the power MOSFET becomes a capacitive load for the output, a large peak current is required for driving
it at a high speed. However, after the charge and discharge, a particularly large current is not required to keep such
condition. In the case of this IC, the peak current capability of 1 A is ensured by taking a capacitance value of
the power MOSFET used into account.
produce ringing to decrease the output pin under
the GND potential. When the voltage decrease of
the output pin becomes larger than the voltage drop
of diode and its voltage becomes negative, the
parasitic diode consisting of the substrate and
collector of the output NPN turns on. This phe-
nomenon can cause the malfunction of device. In
such a case, the Schottky barrier diode should be
connected between the output and GND.
In order to drive the power MOSFET which is a capacitive load at high speed, this IC is adopting the totem pole
The maximum sink/source current is
The peak current capability is mainly required and a particularly too large current is not required constantly.
The parasitic LC of the power MOSFET may
V
OVP
I
V
DS
O
0
0
0
Figure 10. Timer latch basic operation
0.1 A (DC) and the current at peak is 1.0 A (Peak). The circuit is
CC
is under the stop voltage so that it turns off the
OVP
V
TH
Figure 11
7.3 V (typ.)
Schottky barrier
diode
Power supply stop
Power supply stop
Power supply stop
AN8029
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