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CS5156GD16 参数 Datasheet PDF下载

CS5156GD16图片预览
型号: CS5156GD16
PDF下载: 下载PDF文件 查看货源
内容描述: CPU 5位非同步降压控制器 [CPU 5-Bit Nonsynchronous Buck 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
文件页数/大小: 14 页 / 310 K
品牌: CHERRY [ CHERRY SEMICONDUCTOR CORPORATION ]
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Applications Information: continued  
If the short circuit condition is removed, output voltage  
will rise above the 1V level, preventing the FAULT latch  
from being set, allowing normal operation to resume.  
Trace1 - Regulator Output Voltage (1V/div.)  
Trace 2 - Inductor Switching Node (5V/div.)  
Trace 3 - Output Current (13 to 0.5 Amps) (20V/div.)  
Figure 9: CS5156 demonstration board response to 13A load turn off  
Trace 4 - 5V Supply Voltage (2V/div.)  
Trace 3 - Soft Start Timing Capacitor (1V/div.)  
Trace 2 - Inductor Switching Node (2V/div.)  
2
(output set for 2.8V). V  
control topology immediately connects  
inductor to ground, providing 0% duty cycle. Regulation is achieved in  
less than 10µs.  
Figure 10: CS5156 demonstration board hiccup mode short circuit pro-  
tection. Gate pulses are delivered while the soft start capacitor charges,  
and cease during discharge.  
Protection and Monitoring Features  
VCC1 Monitor  
To maintain predictable startup and shutdown characteris-  
tics an internal VCC1 monitor circuit is used to prevent the  
part from operating below 3.75V minimum startup. The  
VCC1 monitor comparator provides hysteresis and guaran-  
tees a 3.70V minimum shutdown threshold.  
Short Circuit Protection  
A lossless hiccup mode short circuit protection feature is  
provided, requiring only the soft start capacitor to imple-  
ment. If a short circuit condition occurs (VFFB < 1V), the VFFB  
low comparator sets the FAULT latch. This causes the MOS-  
FET to shut off, disconnecting the regulator from its input  
voltage. The soft start capacitor is then slowly discharged by  
a 2µA current source until it reaches its lower 0.7V threshold.  
The regulator will then attempt to restart normally, operating  
in its extended off time mode with a 50% duty cycle, while  
the soft start capacitor is charged with a 60µA charge current.  
Trace 4 = 5V from PC Power Supply (2V/div.)  
Trace 2 = Inductor Switching Node (2V/div.)  
If the short circuit condition persists, the regulator output  
will not achieve the 1V low VFFB comparator threshold  
before the soft start capacitor is charged to its upper 2.5V  
threshold. If this happens the cycle will repeat itself until the  
short is removed. The soft start charge/discharge current  
ratio sets the duty cycle for the pulses (2µA/60µA = 3.3%),  
while actual duty cycle is half that due to the extended off  
time mode (1.65%).  
This protection feature results in less stress to the regulator  
components, input power supply, and PC board traces  
than occurs with constant current limit protection (see  
Figures 10 and 11).  
Figure 11: Startup with regulator output shorted.  
Overvoltage Protection  
Overvoltage protection (OVP) is provided as result of the  
2
normal operation of the V  
control topology and requires  
no additional external components. The control loop  
responds to an overvoltage condition within 100ns, causing  
the MOSFET to shut off, disconnecting the regulator from  
its input voltage.  
9
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