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| 型号： | FAN7621N |
| 厂商： | Fairchild Semiconductor |
| 文件页数： | 9/17页 |
| 文件大小： | 0K |
| 描述： | IC OFF-LINE CTRLR PROG PFM 16DIP |
| 标准包装： | 25 |
| 输出隔离： | 隔离 |
| 频率范围： | 94kHz ~ 106kHz |
| 功率（瓦特）： | 1.56W |
| 工作温度： | -40°C ~ 130°C |
| 封装/外壳： | 16-DIP（0.300"，7.62mm） |
| 供应商设备封装： | 16-DIP |
| 包装： | 管件 |
| 产品目录页面： | 1222 (CN2011-ZH PDF) |
Functional Description
1. Basic Operation
Gain
FAN7621 is designed to drive high-side and low-side
MOSFETs complementarily with 50% duty cycle. A fixed
dead time of 350ns is introduced between consecutive
1.8
f min
f normal
f
max
f ISS
transitions, as shown in Figure 16.
Dead t ime
High-side
1.6
1.4
MOSFET
gate drive
1.2
Low-side
MOSFET
gate drve
Figure 16. MOSFETs Gate Drive Signal
time
1.0
0.8
Soft-sta rt
0.6
60
70
80
90
100
110
120
130
140
150
2. Internal Oscillator
FAN7621 employs a current-controlled oscillator, as
Frequency (kHz)
Figure 18. Resonant Converter Typical Gain Curve
shown in Figure 17. Internally, the voltage of R T pin is
regulated at 2V and the charging / discharging current
for the oscillator capacitor, C T , is obtained by copying the
current flowing out of R T pin (I CTC ) using a current mirror.
Therefore, the switching frequency increases as I CTC
increases.
V CC
LV CC
HV CC
RT
V REF
I CTC
+
R max
R min
R SS
HO
I CTC
2I CTC
C T
3V
1V
-
+
-
S Q
R -Q
F/F
C SS
CON
CTR
LO
CS
+
8
R T
-
2V
Counter
(1/4)
Gate drive
SG
PG
R sense
5.2 k Ω
f min =
× 100( kHz )
5.2 k Ω 4.68 k Ω
f max = (
+
) × 100( kHz )
Figure 17. Current Controlled Oscillator
3. Frequency Setting
Figure 18 shows the typical voltage gain curve of a
resonant converter, where the gain is inversely
proportional to the switching frequency in the ZVS
region. The output voltage can be regulated by
modulating the switching frequency. Figure 19 shows the
typical circuit configuration for R T pin, where the opto-
coupler transistor is connected to the R T pin to modulate
the switching frequency.
? 2009 Fairchild Semiconductor Corporation
FAN7621 ? Rev. 1.0.3
9
Figure 19. Frequency Control Circuit
The minimum switching frequency is determined as:
(1)
R min
Assuming the saturation voltage of opto-coupler
transistor is 0.2V, the maximum switching frequency is
determined as:
(2)
R min R max
To prevent excessive inrush current and overshoot of
output voltage during startup, increase the voltage gain
of the resonant converter progressively. Since the
voltage gain of the resonant converter is inversely
proportional to the switching frequency, the soft-start is
www.fairchildsemi.com
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相关代理商/技术参数 |
参数描述 |
|---|---|
| FAN7621S | 制造商:FAIRCHILD 制造商全称:Fairchild Semiconductor 功能描述:PFM Controller for Half-Bridge Resonant Converters |
| FAN7621SJ | 功能描述:功率驱动器IC PWM Control IC for High Power FPS RoHS:否 制造商:Micrel 产品:MOSFET Gate Drivers 类型:Low Cost High or Low Side MOSFET Driver 上升时间: 下降时间: 电源电压-最大:30 V 电源电压-最小:2.75 V 电源电流: 最大功率耗散: 最大工作温度:+ 85 C 安装风格:SMD/SMT 封装 / 箱体:SOIC-8 封装:Tube |
| FAN7621SJX | 功能描述:功率驱动器IC PWM Control IC for High Power FPS RoHS:否 制造商:Micrel 产品:MOSFET Gate Drivers 类型:Low Cost High or Low Side MOSFET Driver 上升时间: 下降时间: 电源电压-最大:30 V 电源电压-最小:2.75 V 电源电流: 最大功率耗散: 最大工作温度:+ 85 C 安装风格:SMD/SMT 封装 / 箱体:SOIC-8 封装:Tube |
| FAN7621SSJ | 功能描述:开关变换器、稳压器与控制器 Contr. for Half-Brdg Resonant Converters RoHS:否 制造商:Texas Instruments 输出电压:1.2 V to 10 V 输出电流:300 mA 输出功率: 输入电压:3 V to 17 V 开关频率:1 MHz 工作温度范围: 安装风格:SMD/SMT 封装 / 箱体:WSON-8 封装:Reel |
| FAN7621SSJX | 功能描述:电流型 PWM 控制器 CONTROL IC OF FPS 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 |
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