1) To meet the minimum load current (>10mA) requirement, R1 is recommended to be 125ohm or lower. As LR1117 -ADJ

can keep itself stable at load current about 2mA, R1 is not allowed to be higher than 625ohm.

2)

this equation: 1/(2

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 LR1117D is very large. LR1117D

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 LR1117D could allow on itself is less than 1W.

And furthermore, LR1117D 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

Load Regulation

0

0.3

0.6

0.9

1.2

1.5

02468

10

12

14

Vin (V)

L 1117 -ADJ Vout Vs. Vin

0

0.3

0.6

0.9

1.2

1.5

0

0.2

0.4

0.6

0.8

1

1.2

Iout (A)

L 1117 -ADJ Vout Vs. Iout

Dropout Voltage

Thermal performance with OTP

0

0.3

0.6

0.9

1.2

1.5

0

0.2

0.4

0.6

0.8

1

1.2

Iout (A)

L 1117 -ADJ Dropout Vs. Iout

0

0.3

0.6

0.9

1.2

1.5

-50

0

50

100

150

200

Temperature ( C)

L 1117 -ADJ Vout Vs. Temp

6/

LESHAN RADIO COMPANY, LTD.