ST AN2378 Application note
AN2378
Application note
Software filter algorithm for open-load detection on the L9935 device
Introduction
This document describes a software algorithm used for detecting an open-load condition. The algorithm refers to the L9935 two-phase stepper motor driver. The algorithm identifies the open-load failure within the failure class and filters out occurrences of false open-load failures.
Figure 1. L9935 bipolar stepper motor driver device
0LFURFRQWUROOHU |
/ |
2SHQ ORDG |
|
|
|
|
|
|
FLUFXLW |
|
|
|
|
|
2SHQ ORDG |
|
|
|
|
|
FLUFXLW |
LO |
% |
|
|
|
|
|
|
|
2SHQ ORDG |
|
|
R |
|
2SHQ ORDG |
|
|
& |
6WHSSHU |
|
6RIWZDUH |
|
|
|
||
'(7(&7,21 |
|
|
0RWRU |
||
ILOWHU |
|
|
& |
||
|
|
|
|
||
|
|
2SHQ ORDG |
RLO |
||
|
|
|
$ |
||
|
|
|
|
|
|
|
|
|
FLUFXLW |
|
|
|
|
|
2SHQ ORDG |
|
|
|
|
|
FLUFXLW |
|
|
|
|
|
*$3*5, |
|
|
February 2011 |
Doc ID 12435 Rev 2 |
1/13 |
www.st.com
Contents |
AN2378 |
|
|
Contents
1 |
When does L9935 open-load checking occur? . . . . . . . . . . . . . . . . . . |
. 5 |
|
|
1.1 |
Full step mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . |
5 |
|
1.2 |
Half step mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . |
6 |
2 |
Open-load detection of L9935 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . |
7 |
|
3 |
L9935 open-load production test . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . |
9 |
|
4 |
Open-load filter algorithm . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . |
10 |
|
Appendix A |
Further information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . |
11 |
|
|
A.1 |
Reference documents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . |
11 |
Revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
2/13 |
Doc ID 12435 Rev 2 |
AN2378 |
List of tables |
|
|
List of tables
Table 1. Production test conditions (Rshunt includes max 0.2 ohm contact resistance) . . . . . . . . . . . 9 Table 2. Document revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
Doc ID 12435 Rev 2 |
3/13 |
List of figures |
AN2378 |
|
|
List of figures
Figure 1. L9935 bipolar stepper motor driver device . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 Figure 2. Output current of L9935 in full step mode. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 Figure 3. Output current of L9935 in half step mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 Figure 4. Open-load detection during free-wheeling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 Figure 5. Open-load measurement concept with simplified Vmes curve (if Vmes < 0 V TLSI is switched
off) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
4/13 |
Doc ID 12435 Rev 2 |
Loading...