FSL106HR Fairchild Semiconductor, FSL106HR Datasheet - Page 9

• Manufacturer Part Number: FSL106HR
• Description: IC PWM/SEMSEFET SMPS 0.5A 8-DIP
• Manufacturer: Fairchild Semiconductor
• Series: FPS™r

Specifications of FSL106HR

• Output Isolation: Isolated
• Frequency Range: 90kHz ~ 110kHz
• Voltage - Input: 9 V ~ 26 V
• Voltage - Output: 650V
• Power (watts): 13W
• Operating Temperature: -40°C ~ 105°C
• Package / Case: 8-DIP (0.300", 7.62mm)
• On Resistance (max): 18 Ohms
• Supply Voltage (max): 26 V
• Supply Current: 2.5 mA
• Maximum Operating Temperature: + 105 C
• Minimum Operating Temperature: - 40 C
• Maximum Power Dissipation: 1.5 W
• Mounting Style: Through Hole
• Operating Temperature Range: - 40 C to + 105 C
• Power Dissipation: 1.5 W
• Switch Current (typ): 2.5 mA
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

© 2010 Fairchild Semiconductor Corporation
FSL106HR • Rev. 1.0.0
Functional Description
Startup
At startup, an internal high-voltage current source
supplies the internal bias and charges the external
capacitor (C
in Figure 14. When V
12V, the FPS™ begins switching and the internal high-
voltage current source is disabled. The FPS continues
normal switching operation and the power is provided
from the auxiliary transformer winding unless V
below the stop voltage of 8V.
Oscillator Block
The oscillator frequency is set internally and the FPS
has
Fluctuation of the switching frequency of a switched
power supply can reduce EMI by spreading the energy
over a wider frequency range than the bandwidth
measured by the EMI test equipment. The amount of
EMI reduction is directly related to the range of the
frequency variation. The range of frequency variation is
fixed internally; however, its selection is randomly
chosen by the combination of external feedback voltage
and internal free-running oscillator. This randomly
chosen switching frequency effectively spreads the EMI
noise nearby switching frequency and allows the use of
a cost-effective inductor instead of an AC input line filter
to satisfy the world-wide EMI requirements.
Figure 15. Frequency Fluctuation Waveform
a
random
A
) connected with the V
Figure 14. Startup Circuit
frequency
CC
reaches the start voltage of
fluctuation
CC
pin, as illustrated
function.
CC
goes
9
Feedback Control
FSL106HR employs current-mode control, as shown in
Figure 16. An opto-coupler (such as the FOD817A) and
shunt regulator (such as the KA431) are typically used
to implement the feedback network. Comparing the
feedback voltage with the voltage across the R
resistor makes it possible to control the switching duty
cycle. When the shunt regulator reference pin voltage
exceeds the internal reference voltage of 2.5V, the
opto-coupler LED current increases, the feedback
voltage V
reduced. This typically occurs when the input voltage is
increased or the output load is decreased.
Leading-Edge Blanking (LEB)
At the instant the internal SenseFET is turned on, the
primary-side capacitance and secondary-side rectifier
diode reverse recovery typically cause a high current
spike through the SenseFET. Excessive voltage across
the R
operation in the current-mode PWM control. To counter
this effect, the FPS employs a leading-edge blanking
(LEB) circuit (see the Figure 16). This circuit inhibits the
PWM comparator for a short time (t
SenseFET is turned on.
Protection Circuits
The FPS has several protective functions, such as
overload protection (OLP), over-voltage protection
(OVP), output-short protection (OSP), under-voltage
lockout (UVLO), abnormal over-current protection
(AOCP), and thermal shutdown (TSD). Because these
various protection circuits are fully integrated in the IC
without external components, the reliability is improved
without increasing cost. Once a fault condition occurs,
switching is terminated and the SenseFET remains off.
This causes V
stop voltage, V
internal high-voltage current source charges the V
capacitor via the V
start voltage, V
operation. In this manner, the auto-restart can
alternately enable and disable the switching of the
power SenseFET until the fault condition is eliminated.
Figure 16. Pulse-Width-Modulation Circuit
SENSE
FB
is pulled down, and the duty cycle is
resistor leads to incorrect feedback
CC
STOP
START
to fall. When V
STR
(8V), the protection is reset and the
pin. When V
(12V), the FPS resumes normal
CC
CC
reaches the UVLO
reaches the UVLO
LEB
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) after the
SENSE
CC