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REG103UA-3.3/2K5 参数 Datasheet PDF下载

REG103UA-3.3/2K5图片预览
型号: REG103UA-3.3/2K5
PDF下载: 下载PDF文件 查看货源
内容描述: 500毫安低压差稳压器 [500mA Low-Dropout Regulator]
分类和应用: 线性稳压器IC调节器电源电路光电二极管输出元件
文件页数/大小: 26 页 / 937 K
品牌: TI [ TEXAS INSTRUMENTS ]
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None of the versions require an output capacitor for regula-  
tor stability. The REG103 will accept any output capacitor  
type less than 1µF. For capacitance values larger than 1µF,  
the effective ESR should be greater than 0.1. This mini-  
mum ESR value includes parasitics such as printed circuit  
board traces, solder joints, and sockets. A minimum 0.1µF  
low ESR capacitor connected to the input supply voltage is  
recommended.  
BASIC OPERATION  
The REG103 series is a family of LDO (Low Drop-Out)  
linear regulators. The family includes five fixed output  
versions (2.5V to 5.0V) and an adjustable output version. An  
internal DMOS power device provides low dropout regula-  
tion with near constant ground pin current (largely indepen-  
dent of load and drop-out conditions) and very fast line and  
load transient response. All versions include internal current  
limit and thermal shutdown circuitry.  
INTERNAL CURRENT LIMIT  
Figure 1 shows the basic circuit connections for the fixed  
voltage models. Figure 2 gives the connections for the  
adjustable output version (REG103A) and example resistor  
values for some commonly used output voltages. Values for  
other voltages can be calculated from the equation shown in  
Figure 2. The SO-8 package provides two pins each for VIN  
and VOUT. Both sets of pins MUST be used and connected  
adjacent to the device.  
The REG103 internal current limit has a typical value of  
700mA. A fold-back feature limits the short-circuit current  
to a typical short-circuit value of 40mA. This circuit will  
protect the regulator from damage under all load conditions.  
A typical characteristic of VOUT versus IOUT is given in  
Figure 3a.  
Care should be taken in high current applications to avoid  
ground currents flowing in the circuit board traces causing  
voltage drops between points on the circuit. If voltage drops  
occur on the circuit board ground that causes the load ground  
voltage to be much lower than the ground voltage seen by  
the ground pin on the REG103, the foldback current may  
approach zero and the REG103 may not start up. In these  
types of applications, a large value resistor can be placed  
between VIN and VOUT to help “boost” up the output of the  
REG103 during start-up, see Figure 3b. The value for the  
“boost” resistor should be chosen so that the current through  
the “boost” resistor is less than the minimum load current:  
RBOOST > (VIN – VOUT)/ILOAD. Typically, a good value for a  
“boost” resistor is 5k.  
ENABLE ERROR  
REG103  
Gnd NR  
VIN  
VOUT  
In  
Out  
COUT  
0.1µF  
CNR  
0.01µF  
Optional  
FIGURE 1. Fixed Voltage Nominal Circuit for REG103.  
ENABLE ERROR  
5
6
EXAMPLE RESISTOR VALUES  
8
7
1
2
VOUT  
V
OUT (V)  
R1 ()(1)  
R2 ()(1)  
VIN  
CFB  
0.01µF  
REG103  
R1  
COUT  
1.295  
2.5  
Short  
Open  
IADJ  
3
0.1µF  
12.1k  
1.21k  
13k  
1.3k  
Load  
Adj  
R2  
4
Gnd  
3
3.3  
5
16.9k  
1.69k  
13k  
1.3k  
Pin numbers for SO-8 package.  
20k  
2.0k  
13k  
1.3k  
Optional  
37.4k  
3.74k  
13k  
1.3k  
VOUT = (1 + R1/R2) 1.295V  
NOTE: (1) Resistors are standard 1% values.  
To reduce current through divider, increase resistor  
values (see table at right).  
As the impedance of the resistor divider increases,  
I
ADJ (~200nA) may introduce an error.  
CFB improves noise and transient response.  
FIGURE 2. Adjustable Voltage Circuit for REG103A.  
REG103  
8
SBVS010D