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UC3825AN 参数 Datasheet PDF下载

UC3825AN图片预览
型号: UC3825AN
PDF下载: 下载PDF文件 查看货源
内容描述: 高速PWM控制器 [High Speed PWM Controller]
分类和应用: 稳压器开关式稳压器或控制器电源电路开关式控制器光电二极管信息通信管理PC
文件页数/大小: 15 页 / 302 K
品牌: TI [ TEXAS INSTRUMENTS ]
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SLUS334C − AUGUST 1995 − REVISED AUGUST 2004  
APPLICATION INFORMATION  
The oscillator of the UC3823A, UC3823B, UC3825A, and UC3825B is a saw tooth. The rising edge is governed by a current  
controlled by the RT pin and value of capacitance at the CT pin (C ). The falling edge of the sawtooth sets dead time for  
CT  
the outputs. Selection of RT should be done first, based on desired maximum duty cycle. CT can then be chosen based  
on the desired frequency (RT) and D . The design equations are:  
MAX  
ǒ1.6   DMAXǓ  
3 V  
R +  
C +  
T
T
10 mA   ǒ1 * DMAXǓ  
ǒR   fǓ  
T
(
)
(1)  
Recommended values for R range from 1 kto 100 k. Control of D  
less than 70% is not recommended.  
T
MAX  
UDG−95102  
Figure 1. Oscillator  
OSCILLATOR FREQUENCY  
vs  
MAXIMUM DUTY CYCLE  
vs  
TIMING RESISTANCE  
TIMING RESISTANCE  
100  
95  
10 M  
1 M  
90  
85  
80  
100 k  
10 k  
75  
70  
10 k  
1 k  
10 k  
100 k  
1 k  
100 k  
R
T
− Timing Resistance − W  
R − Timing Resistance − W  
T
Figure 3  
Figure 2  
6