L6228 STMicroelectronics, L6228 Datasheet - Page 13

• Manufacturer Part Number: L6228
• Description: DMOS DRIVER FOR BIPOLAR STEPPER MOTOR
• Manufacturer: STMicroelectronics

Figure 13 shows the lower limit for the on time t
be said that t
than t
So, small C
switching frequency), but, the smaller is the value for C
performance.
Figure 12. t
Figure 13. Area where t
RCRISE
t



RCRISE
t
t
O N
O N
OFF
>
>
OFF
ON
- t
t
t
= 600 · C
O N MIN
RCRISE
DT
is always bigger than t
value gives more flexibility for the applications (allows smaller on time and, therefore, higher
versus C
. In this last case the device continues to work but the off time t
OFF
–
=
t
DT
ON
1 . 10
1 . 10
2.5 s (typ. value)
OFF
100
100
10
10
1
1
can vary maintaining the PWM regulation.
4
3
0.1
0.1
and R
ON(MIN)
OFF
2.5 s (typ. value)
R
off
because the device imposes this condition, but it can be smaller
ON
= 20k
1
1
for having a good PWM current regulation capacity. It has to
R
off
Coff [nF]
Coff [nF]
OFF
= 47k
, the more influential will be the noises on the circuit
R
off
= 100k
10
10
OFF
100
100
is not more constant.
L6228
13/26