Explanation on ADM3483 Driver Output/Receiver Input Voltage

Document created by analog-archivist Employee on Feb 23, 2016
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I have two questions regarding ADM3483:

Datasheet Rev. E | Page 7 of 20
Absolute maximum rating: Driver Output/Receiver Input Voltage   −7.5 V to +12.5
V
Is this voltage range also valid, in case of VCC is undefined (means the
ADM3483 is not provided with voltage on VCC)?

Please explain “Driver Output/Receiver Input Voltage” more in detail.
Is this the voltage between A to GND and B to GND or the difference voltage
between A and B?
(for example: “A” could be -7.5V and “B” could be at the same time +12.5V)

 

For the Driver Output/Receiver Input Voltage
- The absolute maximum voltage on pin A to Ground, or on pin B to Ground is in
the range −7.5 V to +12.5 V. This is a 'DC' spec.
- Operating at the absolute maximum voltage for extended periods of time is not
recommended.
The absolute maximum ratings also  apply for where the Vcc is unpowered.
It would be possible to have pin A at -7.5V, and B at +12.5V, but this is not
recommended.

If the ADM3483 DE pin is enabled, and the part is transmitting to the bus, or,
for receiving mode with /RE enabled, the following notes apply;
- The voltages  on A and B are constrained by the common mode range operation
of the part (Vcm is -7V to +12V), and by the maximum differential input voltage
for a receiver.
- The table below shows a number of possible combinations, to illustrate
operation over the common mode range of the part. - The scenario where "A"
could be -7.5V and "B" could be at the same time +12.5V leads to a differential
voltage that is greater than the max. allowable specification of +6V.


Va, V
Vb, V
Vcm = (Va+Vb)/2, V
Vdiff = (Va - Vb), V

-7
-6.8
-6.9
-0.2

-6.8
-7
-6.9
0.2

-7
-2
-4.5
-5

-2
-7
-4.5
5

12
11.8
11.9
0.2

11.8
12
11.9
-0.2

12
7
9.5
5

7
12
9.5
-5











12.5
7.5
10
5

7.5
12.5
10
-5

-7.5
-7.3
-7.4
-0.2
!
-7.5
12.5
2.5
-20
!
12.5
-7.5
2.5
20
!




TIA/EIA-485 standard: the resulting differential voltage magnitude is 6 V
maximum.

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