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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5页浏览型号CS3844GDW16的Datasheet PDF文件第6页  
Test Circuit Open Loop Laboratory Test Fixture  
VREF  
RT  
2N2222  
VCC  
A
100k  
COMP  
VFB  
VREF  
4.7kΩ  
0.1µF  
0.1µF  
1kΩ  
Error Amp  
Adjust  
VCC  
1kΩ  
1W  
5kΩ  
Sense  
Adjust  
4.7kΩ  
VOUT  
VOUT  
Sense  
OSC  
Gnd  
Gnd  
CT  
Circuit Description  
Undervoltage Lockout  
During Undervoltage Lockout (Figure 1), the output driv-  
er is biased to sink minor amounts of current. The output  
should be shunted to ground with a resistor to prevent  
activating the power switch with extraneous leakage cur-  
rents.  
VCC  
ON/OFF Command  
to reset of IC  
CSX844 CSX845  
PWM Waveform  
VON  
VOFF  
16V  
10V  
8.4V  
7.6V  
To generate the PWM waveform, the control voltage from  
the error amplifier is compared to a current sense signal  
which represents the peak output inductor current (Figure  
2). An increase in VCC causes the inductor current slope to  
increase, thus reducing the duty cycle. This is an inherent  
feed-forward characteristic of current mode control, since  
the control voltage does not have to change during  
changes of input supply voltage.  
ICC  
When the power supply sees a sudden large output cur-  
rent increase, the control voltage will increase allowing  
the duty cycle to momentarily increase. Since the duty  
cycle tends to exceed the maximum allowed to prevent  
transformer saturation in some power supplies, the inter-  
nal oscillator waveform provides the maximum duty cycle  
clamp as programmed by the selection of OSC compo-  
nents.  
<15mA  
<1mA  
VCC  
VON VOFF  
Figure 1: Startup voltage for CSX844 and CSX845.  
4
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