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| 型号： | FAN6791MY |
| 厂商： | Fairchild Semiconductor |
| 文件页数： | 14/20页 |
| 文件大小： | 0K |
| 描述： | IC REG CTRLR FLYBK ISO CM 16SOIC |
| 标准包装： | 2,500 |
| PWM 型： | 电流模式 |
| 输出数： | 2 |
| 频率 - 最大： | 130kHz |
| 占空比： | 49% |
| 电源电压： | 10 V ~ 22 V |
| 降压： | 无 |
| 升压： | 无 |
| 回扫： | 是 |
| 反相： | 无 |
| 倍增器： | 无 |
| 除法器： | 无 |
| Cuk： | 无 |
| 隔离： | 是 |
| 工作温度： | -40°C ~ 85°C |
| 封装/外壳： | 16-SOIC（0.154"，3.90mm 宽） |
| 包装： | 带卷 (TR) |
Functional Description
The highly integrated FAN6791/3 dual-PWM
combination controller provides several features to
enhance the performance of converters.
Proprietary interleave switching synchronizes the
flyback and forward PWM stages. This reduces
switching noise.
The proprietary frequency jittering function for the
flyback and forward PWM stages helps reduce
switching EMI emissions.
(1)
f PWM =
( kHz )
For the flyback and forward PWM, the synchronized
slope compensation ensures the stability of the current
loop under continuous-mode operation. In addition,
FAN6791/3 provides complete protection functions,
such as brownout protection and RI open/short.
Startup Current
For startup, the HV pin is connected to the line input or
bulk capacitor through external resistor R HV ,
recommended as 100k ? . Typical startup current drawn
from pin HV is 2mA and it charges the hold-up capacitor
through the resistor R HV . When the V DD capacitor level
reaches V DD-ON , the startup current switches off. At this
moment, the V DD capacitor only supplies the FAN6791/3
to maintain the V DD before the auxiliary winding of the
main transformer provides the operating current.
Oscillator Operation
A resistor connected from the RI pin to the GND pin
generates a constant current source for the FAN6791/3
controller. This current is used to determine the center
PWM frequency. Increasing the resistance reduces
PWM frequency. Using a 24k ? resistor results in a
corresponding 65kHz PWM frequency. The switching
frequency is programmed by the resistor R I connected
between RI pin and GND. The relationship is:
1560
R I (k Ω )
The range of the PWM oscillation frequency is designed
as 33kHz ~ 130kHz. FAN6791/3 integrates frequency
hopping function internally. The frequency variation
ranges from around 61kHz to 69kHz for a center
frequency 65kHz. The frequency hopping function helps
reduce EMI emission of a power supply with minimum
line filters.
For power saving, flyback PWM stage has a green
mode function. Frequency linearly decreases when V FB
is within V G and V N . Once V FB is lower than V G ,
switching frequency disables, and it enters burst mode.
? 2008 Fairchild Semiconductor Corporation
FAN6791 / FAN6793 ? Rev. 1.0.3
14
Figure 23. Oscillation Frequency in Green Mode
Line Voltage Detection (V RMS )
Figure 24 shows a resistive divider with low-pass
filtering for line-voltage detection on VRMS pin. The
V RMS voltage is used for high/low line compensation that
keeps the constant power limit and provides brownout
protection. For brownout protection, when the V RMS
voltage drops below 0.8V, OPWM turns off.
Figure 24. Line-Voltage Detection on VRMS Pin
Remote On/Off
Figure 25 shows the remote on / off function. When the
supervisor FPO pin pulls down and enables the system
by connecting an opto-coupler, V REF applies to the
ON/OFF pin to enable forward PWM stage.
Figure 25. Remote On/Off
www.fairchildsemi.com
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相关代理商/技术参数 |
参数描述 |
|---|---|
| FAN6791NY | 功能描述:电流型 PWM 控制器 Highly Integratd Grn Mode PWM Controller RoHS:否 制造商:Texas Instruments 开关频率:27 KHz 上升时间: 下降时间: 工作电源电压:6 V to 15 V 工作电源电流:1.5 mA 输出端数量:1 最大工作温度:+ 105 C 安装风格:SMD/SMT 封装 / 箱体:TSSOP-14 |
| FAN6793 | 制造商:FAIRCHILD 制造商全称:Fairchild Semiconductor 功能描述:Highly Integrated,Dual-PWM Combination Controller |
| FAN6793MY | 功能描述:监控电路 Highly Intgrtd Dual PWM Combo Controller RoHS:否 制造商:STMicroelectronics 监测电压数: 监测电压: 欠电压阈值: 过电压阈值: 输出类型:Active Low, Open Drain 人工复位:Resettable 监视器:No Watchdog 电池备用开关:No Backup 上电复位延迟（典型值）:10 s 电源电压-最大:5.5 V 最大工作温度:+ 85 C 安装风格:SMD/SMT 封装 / 箱体:UDFN-6 封装:Reel |
| FAN6793NY | 功能描述:监控电路 Highly Intgrtd Dual PWM Combo Controller RoHS:否 制造商:STMicroelectronics 监测电压数: 监测电压: 欠电压阈值: 过电压阈值: 输出类型:Active Low, Open Drain 人工复位:Resettable 监视器:No Watchdog 电池备用开关:No Backup 上电复位延迟（典型值）:10 s 电源电压-最大:5.5 V 最大工作温度:+ 85 C 安装风格:SMD/SMT 封装 / 箱体:UDFN-6 封装:Reel |
| FAN6861 | 制造商:FAIRCHILD 制造商全称:Fairchild Semiconductor 功能描述:Low-Cost, Highly Integrated, Green-Mode PWM Controller for Peak Power Management |
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