Datasheet

11/25
L6235
Figure 10 shows the lower limit for the On Time t
ON
for having a good PWM current regulation capacity. It has
to be said that t
ON
is always bigger than t
ON(MIN)
because the device imposes this condition, but it can be smaller
than t
RCRISE
- t
DT
. In this last case the device continues to work but the Off Time t
OFF
is not more constant.
So, small C
OFF
value gives more flexibility for the applications (allows smaller On Time and, therefore, higher
switching frequency), but, the smaller is the value for C
OFF
, the more influential will be the noises on the circuit
performance.
Figure 9. t
OFF
versus C
OFF
and R
OFF
.
Figure 10. Area where t
ON
can vary maintaining the PWM regulation.
0.1 1 10 100
1
10
100
1
.
10
3
1
.
10
4
Coff [nF]
toff [µs]
R
off
= 100k
Ω
R
off
= 47k
Ω
R
off
= 20k
Ω
0.1 1 10 100
1
10
100
Coff [nF]
ton(min) [
µ
s]
1.5
µ
s (typ. value)