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CS3844GDW16 参数 Datasheet PDF下载

CS3844GDW16图片预览
型号: CS3844GDW16
PDF下载: 下载PDF文件 查看货源
内容描述: 电流模式PWM控制电路与50 %最大占空比 [Current Mode PWM Control Circuit with 50% Max Duty Cycle]
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
文件页数/大小: 6 页 / 159 K
品牌: CHERRY [ CHERRY SEMICONDUCTOR CORPORATION ]
 浏览型号CS3844GDW16的Datasheet PDF文件第1页浏览型号CS3844GDW16的Datasheet PDF文件第2页浏览型号CS3844GDW16的Datasheet PDF文件第3页浏览型号CS3844GDW16的Datasheet PDF文件第4页浏览型号CS3844GDW16的Datasheet PDF文件第6页  
Circuit Description: continued  
Setting the Oscillator  
The times Tc and Td can be determined as follows:  
V
OSC  
VREF - Vlower  
tc = RTCT ln  
OSC  
RESET  
(
)
VREF - Vupper  
Toggle  
F/F Output  
VREF - IdRT - Vlower  
VREF - IdRT - Vupper  
td = RTCT ln  
(
)
EA Output  
Switch  
Current  
Substituting in typical values for the parameters in the  
above formulas:  
V
CC  
VREF = 5.0V, Vupper = 2.7V, Vlower = 1.0V, Id = 8.3mA,  
then  
I
O
O
tc 0.5534RTCT  
V
2.3 - 0.0083 RT  
td = RTCT ln  
(
)
4.0 - 0.0083 RT  
Figure 2: Timing Diagram  
For better accuracy RT should be 10k.  
V
V
upper  
Grounding  
lower  
High peak currents associated with capacitive loads neces-  
sitate careful grounding techniques. Timing and bypass  
capacitors should be connected close to Gnd in a single  
point ground.  
t
t
off  
on  
t
d
t
C
The transistor and 5kpotentiometer are used to sample  
the oscillator waveform and apply an adjustable ramp to  
Sense.  
t
t
t
on = C  
t
2t  
d
off = C+  
Figure 3: Duty Cycle parameters.  
5
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