Itron 0001 ユーザーズマニュアル

    July 23, 2002 

 

 

In order to size the pull-up resistor properly, you must know the above parameters. 
The following example demonstrates a suitable procedure for sizing the resistor.

System specifications:

V

PU

+ = 12V

V

OHmin

 * = 10V

R

L

 = 10 kohms

+ V

PU

 = pull-up voltage.

*V

OHmin

 = Minimum voltage allowed on the output in the high state.

First, you must determine the current required by the supply voltage in the high 

state. The minimum load current in the high state, I

Lmin

, is given by: 

 ILmin = VOHmin / RL = 1 mA

From this, determine the value of the pull-up resistor. Use the worst case 

condition of 10V along with the value of I

L

 determined above.

 RPU = (12V - 10V)/ ILmin = 2000 ohms

000168

0

2

4

6

8

10

12

14

16

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

4.5

5.0

5.5

6.0

6.5

7.0

7.5

8.0

8.5

9.0

9.5

10.0