LR1117C Ver la hoja de datos (PDF) - Leshan Radio Company,Ltd
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Fabricante
LR1117C Datasheet PDF : 10 Pages
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LESHAN RADIO COMPANY, LTD.
1) To meet the minimum load current (>10mA) requirement, R1 is recommended to be 125ohm or lower. As LR1117C-ADJ
can keep itself stable at load current about 2mA, R1 is not allowed to be higher than 625ohm.
2) Using a bypass capacitor (CADJ) between the ADJ pin and ground can improve ripple rejection. This bypass capacitor
prevents ripple from being amplified as the output voltage is increased. The impedance of CADJ should be less than R1
to prevent ripple from being amplified. As R1 is normally in the range of 100Ω~500Ω, the value of CADJ should satisfy
this equation: 1/(2frippleCADJ)<R1.
THERMAL CONSIDERATIONS
We have to take heat dissipation into great consideration when output current or differential voltage of input and
output voltage is large. Because in such cases, the power dissipation consumed by LR1117 is very large. LR1117 series
uses SOT-223 package type and its thermal resistance is about 20°C/W. And the copper area of application board can
affect the total thermal resistance. If copper area is 5cm*5cm (two sides), the resistance is about 30°C/W. So the total
thermal resistance is about 20°C/W + 30°C/W. We can decrease total thermal resistance by increasing copper area in
application board. When there is no good heat dissipation copper are in PCB, the total thermal resistance will be as
high as 120°C/W, then the power dissipation of LR1117 could allow on itself is less than 1W. And furthermore, LR1117
will work at junction temperature higher than 125°C under such condition and no lifetime is guaranteed.
TYPICAL PERFORMANCE CHARACTERISTICS
T=25°C unless specified.
Line Regulation
LC1117-ADJ Vout Vs. Vin
1.5
1.2
0.9
0.6
0.3
0
0
2
4
6
8
10
12
14
Vin (V)
Dropout Voltage
LC1117-ADJ Dropout Vs. Iout
1.5
1.2
0.9
0.6
0.3
0
0
0.2
0.4
0.6
0.8
1
1.2
Iout (A)
Load Regulation
LC1117-ADJ Vout Vs. Iout
1.5
1.2
0.9
0.6
0.3
0
0
0.2
0.4
0.6
0.8
1
1.2
Iout (A)
Thermal performance with OTP
LC1117-ADJ Vout Vs. Temp
1.5
1.2
0.9
0.6
0.3
0
-50
0
50
100
150
200
Temperature (C)
Feb 2011 Ver1.2
6/10
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