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GM66300-2.5TA3R 参数 Datasheet PDF下载

GM66300-2.5TA3R图片预览
型号: GM66300-2.5TA3R
PDF下载: 下载PDF文件 查看货源
内容描述: 超3A低压降稳压器 [3A ULTRA LOW-DROPOUT REGULATOR]
分类和应用: 稳压器
文件页数/大小: 11 页 / 347 K
品牌: GAMMA [ GAMMA MICROELECTRONICS INC. ]
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APPLICATION INFORMATION  
The GM66300 series is a high performance with low-  
dropout voltage regulator, suitable for moderate to  
high-current voltage regulator applications. Its 500mV  
dropout voltage at full load makes it especially valuable  
in battery-powered systems and as a high-efficiency  
noise filter in post-regulator applications.  
Calculate the power dissipation of the regulator from  
these numbers and the device parameters from this  
datasheet, where the ground current is taken from  
data sheet  
P = (V - V )I  
D IN  
+ V  
I
OUT OUT  
IN  
GND  
The heat sink thermal resistance is determined by:  
T - TA  
J(MAX)  
Unlike older NPN-pass transistor designs, where the  
minimum dropout voltage is limited by the base-to-  
emitter voltage drop and collector-to-emitter saturation  
voltage. Dropout performance of the PNP output of  
q
=
- (q + q  
JC  
)
SA  
CS  
P
D
these devices is limited only by the low V saturation  
CE  
where T  
125°C and q is between 0°C and  
CS  
J(max)  
Voltage.  
2°C/W.  
The GM66300 series regulator is fully protected from  
damage due to fault conditions. Current limiting is  
provided. This limiting is linear, output current during  
overload conditions is constant. Thermal shutdown  
disables the device when the die temperature exceeds  
the maximum safe operating temperature. Transient  
protection allows device (and load) survival even when  
the input voltage spikes above and below nominal. The  
output structure of these regulators allows voltages in  
excess of the desired output voltage to be applied  
without reverse current flow.  
The heat sink may be significantly reduced in  
applications where the minimum input voltage is  
known and is large compared with the dropout  
voltage. Use a series input resistor to drop  
excessive voltage and distribute the heat between  
this resistor and the regulator. The low dropout  
properties of Super beta PNP regulators allow  
significant reductions in regulator power dissipation  
and the associated heat sink without compromising  
performance. When this technique is employed, a  
capacitor of at least 1.0µF is needed directly  
between the input and regulator ground.  
V
GM66300 - X.X  
V
Output Capacitor  
IN  
OUT  
V
V
OUT  
IN  
The GM66300 series requires an output capacitor to  
maintain stability and improve transient response.  
Proper capacitor selection is important to ensure  
proper operation. The GM66300 series output  
capacitor selection is dependent upon the ESR  
(equivalent series resistance) of the output capacitor  
to maintain stability. When the output capacitor is  
47µF or greater, the output capacitor should have  
GND  
+
+
C
C
IN  
OUT  
less than 1W of ESR. This will improve transient  
response as well as promote stability. Ultra-low-ESR  
capacitors, such as ceramic chip capacitors may  
promote instability. These very low ESR levels may  
cause an oscillation and/or underdamped transient  
response. When larger capacitors are used, the  
ESR requirement approaches zero. A 100µF  
ceramic capacitor can be used on the output while  
maintaining stability. A low-ESR 47µF solid tantalum  
capacitor works extremely well and provides good  
transient response and stability over temperature.  
Aluminum electrolytics can also be used, as long as  
the ESR of the capacitor is 1W.  
Figure 10. Capacitor Requirements  
Thermal Design  
Linear regulators are simple to use. The most  
complicated design parameters to consider are thermal  
characteristics.  
Thermal design requires four application-specific  
parameters:  
Maximum ambient temperature (T )  
A
Output Current (I  
)
OUT  
Output Voltage (V  
)
OUT  
Input Voltage (V )  
IN  
The value of the output capacitor can be increased  
without limit. Higher capacitance values help to  
improve transient response, ripple rejection, and  
reduce output noise.  
Ground Current (I  
)
GND  
6