FAN7930BMX Fairchild Semiconductor, FAN7930BMX Datasheet - Page 16

• Manufacturer Part Number: FAN7930BMX
• Description: Power Factor Correction ICs Critical Conduction Mode PFC Controller
• Manufacturer: Fairchild Semiconductor

Specifications of FAN7930BMX

• Switching Frequency: 300 KHz
• Maximum Operating Temperature: + 125 C
• Mounting Style: SMD/SMT
• Minimum Operating Temperature: - 40 C
• Package / Case: SOP-8
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

© 2010 Fairchild Semiconductor Corporation
FAN7930B • Rev. 1.0.2
10. Input Voltage Absent Detection: To save power
loss caused by input voltage sensing resistors and to
optimize THD easily, the FAN7930B omits AC input
voltage detection. Therefore, no information about AC
input is available from the internal controller. In many
cases, the V
independent power source like standby power. In this
scheme, some mismatch may exist. For example, when
the electric power is suddenly interrupted during two or
three AC line periods; V
but output voltage drops because there is no input
power source. Consequently, the control loop tries to
compensate for the output voltage drop and V
reaches its maximum. This lasts until AC input voltage is
live again. When AC input voltage is live again, high
V
put on the MOSFET and diode. To protect against this,
FAN7930B internally checks if the input AC voltage
exists. If input does not exist, soft-start is reset and
waits until AC input is live again. Soft-start manages the
turn-on time for smooth operation when it detects AC
input is applied again and applies less voltage and
current stress on startup.
COMP
Figure 41.
allows high switching current and more stress is
CC
of PFC controller is supplied by an
Operation without Input Voltage
Absent Circuit
CC
is still alive during that time,
COMP
16
11. Current Sense: The MOSFET current is sensed
using an external sensing resistor for the over-current
protection. If the CS pin voltage is higher than 0.8V, the
over-current
protection signal. An internal RC filter of 40kΩ and 8pF
is included to filter switching noise.
12. Gate Driver Output: FAN7930B contains a single
totem-pole output stage designed for a direct drive of
the power MOSFET. The drive output is capable of up
to +500/-800mA peak current with a typical rise and fall
time of 50ns with 1nF load. The output voltage is
clamped to 13V to protect the MOSFET gate even if the
V
MOSFET Gate
V
V
NewV
CC
V
OUT
AUX
I
DS
IN
FAN7930 Rev.00
voltage is higher than 13V.
COMP
Figure 42. Operation with Input Voltage
protection
f
Though V
operation of controller is
MIN
normal due to the large
D
MAX
bypass capacitor.
Absent Circuit
IN
Input Voltage Absent Detected
is eliminated,
f
comparator
MIN
D
MIN
generates
Smooth Soft-
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