Philips Semiconductors
PCA82C250 / 251 CAN Transceiver
Application Note
AN96116
Normally for slope control mode the resistor R
is connected between the input Rs and and a logic LOW-level
ext
(V ), provided either by a port output or a ground line. Thus the relation between the single-ended slew rate and
OL
the resistance R
is given by the following equation:
ext
V
– V
V
– V
Rs OL
Rs
OL
SR = --------------------------- = ----------------------------------------------------- .
(4)
k
× R
µs
-------
kΩ
–3
SE
ext
7.6 × 10
× R
ext
Example 1:
With R
= 24 kΩ and V
= 0V the single-ended slew rate typically would be
0.5V
ext
OL
V
– V
OL
V
= 14------
µs
0.5 × 5V
Rs
CC
SR =
=
=
---------------------------
-----------------------------------------------------
--------------------------------------------------------
µs
k
× R
µs
–3
–3
SE
ext
7.6 × 10 ------- × R
7.6 × 10 ------- × 24kΩ
kΩ
ext
kΩ
Example 2:
To achieve a single-ended slew rate of 5 V/µs the typical slope-control resistance would be
V
– V
0.5V
CC
0.5 × 5 V
----------------------------------------------------
µs
Rs
OL
R
=
=
=
= 66 kΩ ===> R
= 68 kΩ
ext
--------------------------
--------------------------------------------------
µs
ext
k
× SR
V
–3
–3
SE
7.6 × 10 ------- × SR
kΩ
7.6 × 10 ------- × 5 ------
kΩ µ s
15
NXP [ NXP ]
