參數(shù)資料
型號(hào): FSQ0765RQ
廠商: FAIRCHILD SEMICONDUCTOR CORP
元件分類: 穩(wěn)壓器
英文描述: 3.92 A SWITCHING CONTROLLER, 75.8 kHz SWITCHING FREQ-MAX, ZFM6
封裝: ROHS COMPLIANT, TO-220F, 6 PIN
文件頁數(shù): 6/19頁
文件大?。?/td> 3321K
代理商: FSQ0765RQ
F
S
Q0
765RQ
Green
-Mode
Farich
ild
P
o
we
rSw
itch
(FPS)
for
Quasi
-Resonant
Operatio
n
2008 Fairchild Semiconductor Corporation
www.fairchildsemi.com
FSQ0765RQ Rev. 1.0.1
14
4.1 Overload Protection (OLP): Overload is defined as
the load current exceeding its normal level due to an
unexpected abnormal event. In this situation, the
protection circuit should trigger to protect the SMPS.
However, even when the SMPS is in the normal
operation, the overload protection circuit can be
triggered during the load transition. To avoid this
undesired operation, the overload protection circuit is
designed to trigger only after a specified time to
determine whether it is a transient situation or a true
overload situation. Because of the pulse-by-pulse
current limit capability, the maximum peak current
through the SenseFET is limited, and therefore the
maximum input power is restricted with a given input
voltage. If the output consumes more than this maximum
power, the output voltage (VO) decreases below the set
voltage. This reduces the current through the opto-
coupler LED, which also reduces the opto-coupler
transistor current, thus increasing the feedback voltage
(VFB). If VFB exceeds 2.5V, D1 is blocked and the 5A
current source starts to charge CB slowly up to VCC. In
this condition, VFB continues increasing until it reaches
6V, when the switching operation is terminated, as
shown in Figure 29. The delay time for shutdown is the
time required to charge CFB from 2.5V to 6V with 5A. A
20 ~ 50ms delay time is typical for most applications.
Figure 29. Overload Protection
4.2 Abnormal Over-Current Protection (AOCP): When
the secondary rectifier diodes or the transformer pins are
shorted, a steep current with extremely high di/dt can
flow through the SenseFET during the LEB time. Even
though the FSQ-series has overload protection, it is not
enough to protect the FSQ-series in that abnormal case,
since severe current stress is imposed on the SenseFET
until OLP triggers. The FSQ-series has an internal
AOCP circuit shown in Figure 30. When the gate turn-on
signal is applied to the power SenseFET, the AOCP
block is enabled and monitors the current through the
sensing resistor. The voltage across the resistor is
compared with a preset AOCP level. If the sensing
resistor voltage is greater than the AOCP level, the set
signal is applied to the latch, resulting in the shutdown of
the SMPS.
Figure 30. Abnormal Over-Current Protection
4.3 Output-Short Protection (OSP): If the output is
shorted, steep current with extremely high di/dt can flow
through the SenseFET during the LEB time. Such a
steep current brings high voltage stress on the drain of
SenseFET when turned off. To protect the device from
such an abnormal condition, OSP is included in the FSQ-
series. It is comprised of detecting VFB and SenseFET
turn-on time. When the VFB is higher than 2V and the
SenseFET turn-on time is lower than 1.2s, the FPS
recognizes this condition as an abnormal error and shuts
down PWM switching until VCC reaches Vstart again. An
abnormal condition output short is shown in Figure 31.
Figure 31. Output Short Waveforms
4.4 Over-Voltage Protection (OVP): If the secondary-
side feedback circuit malfunctions or a solder defect
causes an opening in the feedback path, the current
through the opto-coupler transistor becomes almost
zero. Then, VFB climbs up in a similar manner to the
overload situation, forcing the preset maximum current
to be supplied to the SMPS until the overload protection
triggers. Because more energy than required is provided
to the output, the output voltage may exceed the rated
voltage before the overload protection triggers, resulting
in the breakdown of the devices in the secondary side.
To prevent this situation, an OVP circuit is employed. In
general, the peak voltage of the sync signal is
proportional to the output voltage and the FSQ-series
V
FB
t
2.5V
6.0V
Overload protection
t
12= CFB*(6.0-2.5)/Idelay
t
1
t
2
FSQ0765R Rev.00
2
S
Q
R
OSC
R
3R
GND
Gate
driver
LEB
250ns
PWM
+
-
V
OCP
AOCP
R
sense
FSQ0765R Rev.00
D
MOSFET
Drain
Current
Rectifier
Diode Current
V
FB
V
o
0
output short occurs
1.2us
I
o
0
I
LIM
Turn-off delay
Minimum turn-on time
FSQ0765R Rev. 00
相關(guān)PDF資料
PDF描述
FUSION878A COLOR SIGNAL DECODER, PQFP128
FVXO-HC53BR-FREQ VCXO, CLOCK, 0.75 MHz - 250 MHz, HCMOS OUTPUT
FVXO-HC72BR-FREQ VCXO, CLOCK, 0.75 MHz - 180 MHz, HCMOS OUTPUT
FVXO-HC73B-FREQ VCXO, CLOCK, 0.75 MHz - 250 MHz, HCMOS OUTPUT
FVXO-LC52BR-FREQ VCXO, CLOCK, 0.75 MHz - 1000 MHz, LVDS OUTPUT
相關(guān)代理商/技術(shù)參數(shù)
參數(shù)描述
FSQ0765RQLDTU 功能描述:電源開關(guān) IC - 配電 SMPS Power switch (QRC) 7A 650V RoHS:否 制造商:Exar 輸出端數(shù)量:1 開啟電阻(最大值):85 mOhms 開啟時(shí)間(最大值):400 us 關(guān)閉時(shí)間(最大值):20 us 工作電源電壓:3.2 V to 6.5 V 電源電流(最大值): 最大工作溫度:+ 85 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:SOT-23-5
FSQ0765RQUDTU 功能描述:電源開關(guān) IC - 配電 SMPS Power SW (QRC) 7A 650V RoHS:否 制造商:Exar 輸出端數(shù)量:1 開啟電阻(最大值):85 mOhms 開啟時(shí)間(最大值):400 us 關(guān)閉時(shí)間(最大值):20 us 工作電源電壓:3.2 V to 6.5 V 電源電流(最大值): 最大工作溫度:+ 85 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:SOT-23-5
FSQ0765RQWDTU 功能描述:電源開關(guān) IC - 配電 SMPS Power Switch RoHS:否 制造商:Exar 輸出端數(shù)量:1 開啟電阻(最大值):85 mOhms 開啟時(shí)間(最大值):400 us 關(guān)閉時(shí)間(最大值):20 us 工作電源電壓:3.2 V to 6.5 V 電源電流(最大值): 最大工作溫度:+ 85 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:SOT-23-5
FSQ0765RS 制造商:FAIRCHILD 制造商全稱:Fairchild Semiconductor 功能描述:Green-Mode Fairchild Power Switch (FPS) for Quasi-Resonant Operation - Low EMI and High Efficiency
FSQ0765RSLDTU 功能描述:電源開關(guān) IC - 配電 SMPS Power switch (QRC) 7A 650V RoHS:否 制造商:Exar 輸出端數(shù)量:1 開啟電阻(最大值):85 mOhms 開啟時(shí)間(最大值):400 us 關(guān)閉時(shí)間(最大值):20 us 工作電源電壓:3.2 V to 6.5 V 電源電流(最大值): 最大工作溫度:+ 85 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:SOT-23-5