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| 型号： | FL7930CM |
| 厂商： | Fairchild Semiconductor |
| 文件页数： | 14/23页 |
| 文件大小： | 0K |
| 描述： | IC PFC CTLR FLYBACK/BOUND 8SOICN |
| 标准包装： | 95 |
| 类型： | 镇流器控制器 |
| 频率： | 250kHz ~ 350kHz |
| 电流 - 电源： | 2.5mA |
| 电源电压： | 13 V ~ 20 V |
| 工作温度： | -40°C ~ 125°C |
| 封装/外壳： | 8-SOIC（0.154"，3.90mm 宽） |
| 供应商设备封装： | 8-SOP |
| 包装： | 管件 |
V DS
V OUTPFC - V IN
V OUTPFC - V IN
ZCD after COMPARATOR
Ignores ZCD
Noise
V IN
MOSFET Gate
Error Happens!
I INDUCTOR
Max f SW Limit
V ZCD
I MOSFET
I DIODE
Inhibit Region
Figure 31. Maximum Switching Frequency
Limit Operation
t
6. Control : The scaled output is compared with the
1.5V
MOSFET gate
ON
Figure 29.
1.4V
150ns Delay
ON
Auxiliary Voltage Threshold
t
internal reference voltage and sinking or sourcing
current is generated from the COMP pin by the
transconductance amplifier. The error amplifier output is
compared with the internal sawtooth waveform to give
proper turn-on time based on the controller.
V OUTPFC
6.2V
When no ZCD signal is available, the PFC controller
cannot turn on the MOSFET, so the controller checks
every switching off time and forces MOSFET turn on
when the off time is longer than 150 μs. This restart
timer triggers MOSFET turn-on at startup and may be
INV
1
THD optimized
Sawtooth
Generator
1V
Sawtooth
V REF
Stair
Step
-
+
+
-
MOSFET Off
used at the input voltage zero cross period.
COMP
3
Clamp
Circuit
V OUT
V IN
C2
R1
C1
V CC
Figure 32.
Control Circuit
t RESTART
150 ? s
MOSFET Gate
ZCD after COMPARATOR
Unlike a conventional voltage-mode PWM controller,
FL7930B turns on the MOSFET at the falling edge of
ZCD signal. The “ON” instant is determined by the
external signal and the turn-on time lasts until the error
amplifier output (V COMP ) and sawtooth waveform meet.
When load is heavy, output voltage decreases, scaled
output decreases,
COMP
voltage increases
to
t
compensate low output, turn-on time lengthens to give
Figure 30.
Restart Timer at Startup
more inductor turn-on time, and increased inductor
Because the MOSFET turn-on depends on the ZCD
input, switching frequency may increase to higher than
several megahertz due to the mis-triggering or noise on
the nearby ZCD pin. If the switching frequency is higher
than needed for critical conduction mode (CRM),
operation mode shifts to continuous conduction mode
(CCM). In CCM, unlike CRM where the boost inductor
current is reset to zero at the next switch on; inductor
current builds up at every switching cycle and can be
raised to very high current that exceeds the current
rating of the power switch or diode. This can seriously
damage the power switch. To avoid this, maximum
switching frequency limitation is embedded. If ZCD
signal is applied again within 3.3 μs after the previous
rising edge of gate signal, this signal is ignored
internally and FL7930B waits for another ZCD signal.
This slightly degrades the power factor performance at
current raises the output voltage. This is how a PFC
negative feedback controller regulates output.
The maximum of V COMP is limited to 6.5 V, which
dictates the maximum turn-on time. Switching stops
when V COMP is lower than 1.0 V.
ZCD after COMPARATOR
V COMP & Sawtooth
0 . 155 V / ? s
MOSFET Gate
t
light load and high input voltage.
Figure 33.
Turn-On Time Determination
? 2010 Fairchild Semiconductor Corporation
FL7930B ? Rev. 1.0.4
14
www.fairchildsemi.com
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相关代理商/技术参数 |
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|---|---|
| FL7930CMX | 功能描述:功率因数校正 IC Single Stage Flyback PFC Controller RoHS:否 制造商:Fairchild Semiconductor 开关频率:300 KHz 最大功率耗散: 最大工作温度:+ 125 C 安装风格:SMD/SMT 封装 / 箱体:SOIC-8 封装:Reel |
| FL7930CMX_G | 制造商:Fairchild Semiconductor Corporation 功能描述:IC PFC CTLR FLYBACK/BOUND 8SOIC |
| FL793-F8 | 制造商:BACO Controls Inc 功能描述: |
| FL7B5BH | 制造商:未知厂家 制造商全称:未知厂家 功能描述:Ball-Grid-Array Thin Film Low-Pass Filter |
| FL7KM12A | 制造商:未知厂家 制造商全称:未知厂家 功能描述:TRANSISTOR | MOSFET | N-CHANNEL | 600V V(BR)DSS | 7A I(D) | TO-220FN |
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