L9935 - STMicroelectronics

L9935
Two-phase stepper motor driver
Features
■
2 x 1.1 A full bridge outputs
■
Integrated chopping current regulation
■
Minimized power dissipation during flyback
■
Output stages with controlled output voltage
slopes to reduce electromagnetic radiation
'!0'03
PowerSO20
■
Short-circuit protection of all outputs
■
Error-flag for over load, open load and over
temperature pre alarm
■
Delayed channel switch on to reduce peak
currents
Description
■
Max. operating supply voltage 24 V
■
Standby consumption typically 40 µA
The L9935 is a two-phase stepper motor driver
circuit suited to drive bipolar stepper motors.
■
Serial interface (SPI)
Table 1.
The device can be controlled by a serial interface
(SPI). All protections required to design a well
protected system (short-circuit, over temperature,
cross conduction etc.) are integrated.
Device summary
Order code
Package
Packing
L9935
PowerSO20
Tube
L9935013TR
PowerSO20
Tape and reel
September 2013
Doc ID 5198 Rev 10
1/29
www.st.com
1
Contents
L9935
Contents
1
Block diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
2
Pin description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
3
Electrical specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
3.1
Absolute maximum ratings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
3.2
Thermal data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
3.3
Electrical characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
4
Application hints . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
5
Functional description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
5.1
Basic structure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
5.2
Full bridge function . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
5.2.1
No current . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
5.2.2
Turning on . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
5.2.3
Chopping . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
5.2.4
Reversing phase . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
5.2.5
Chopper control by oscillator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
5.3
Protection and diagnosis functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
5.4
Short from an output to the supply voltage VS
5.5
Diagnosis of a short to VS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
5.6
Short from an output to ground . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
5.7
Diagnosis of a short to ground . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
5.8
Shorted load . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
5.9
Diagnosis of a shorted load . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
5.10
Open load . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
5.10.1
5.11
Over temperature pre alarm . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
Application hints using a high resistive stepper motor . . . . . . . . . . . . . . . 18
5.11.1
Startup behavior . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
5.12
Limitation of the diagnosis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
5.13
Serial data interface (SPI) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
5.13.1
2/29
. . . . . . . . . . . . . . . . . . . . . . . . . . . 15
Startup of the serial data interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
Doc ID 5198 Rev 10
L9935
Contents
5.14
Test condition for all propagation times . . . . . . . . . . . . . . . . . . . . . . . . . . 21
5.15
Cascading several devices . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
5.16
Application information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
5.17
Electromagnetic emission classification (EME) . . . . . . . . . . . . . . . . . . . . 25
6
Package information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
7
Revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
Doc ID 5198 Rev 10
3/29
List of tables
L9935
List of tables
Table 1.
Table 2.
Table 3.
Table 4.
Table 5.
Table 6.
Table 7.
Table 8.
Table 9.
Table 10.
Table 11.
Table 12.
Table 13.
4/29
Device summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
Pin function . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Absolute maximum ratings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Thermal data. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Electrical characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Current setting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
High and low resistive motor (error bits) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
Diagnosis description - bit7 and bit6 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
Test condition for all propagation times . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
Full step mode control sequences and diagnosis response . . . . . . . . . . . . . . . . . . . . . . . . 23
Half step mode control sequences and diagnosis response . . . . . . . . . . . . . . . . . . . . . . . 24
Electromagnetic emission . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
Document revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
Doc ID 5198 Rev 10
L9935
List of figures
List of figures
Figure 1.
Figure 2.
Figure 3.
Figure 4.
Figure 5.
Figure 6.
Figure 7.
Figure 8.
Figure 9.
Figure 10.
Figure 11.
Figure 12.
Figure 13.
Figure 14.
Figure 15.
Block diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Pin connection (top view) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
General application circuit proposal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Typical average load current dependence on RSense . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
Displays a full bridge including the current sense circuit. . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Principal chopper control circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
Pulse diagram to explain offset chopping . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
Normal PWM current versus short circuit current and detection of short to VS . . . . . . . . . 16
SPI data/clock timing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
Cascading several stepper motor drivers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
Control sequence for 3 Stepper motor drivers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
Paralleling several devices . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
State diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
EMC compatibility for L9935 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
PowerSO20 mechanical data and package dimensions . . . . . . . . . . . . . . . . . . . . . . . . . . 27
Doc ID 5198 Rev 10
5/29
Block diagram
1
L9935
Block diagram
Figure 1.
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6/29
Doc ID 5198 Rev 10
L9935
2
Pin description
Pin description
Figure 2.
Pin connection (top view)
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Table 2.
Pin function
Pin No
Name
Description
1,10,11,20
GND
2
OUTA1
3
SCK
Clock for serial interface (SPI)
4
SDI
Serial data input
5
SDO
Serial data output
6
VCC
5V logic supply voltage
7
CSN
Chip select (Low active)
8
EN
9
OUTB1
12
SRB
13
OUTB2
14
CDRV
Charge pump buffer capacitor
15
OSC
Oscillator capacitor or external clock
16
VS
Supply voltage
17
NC
Not connected
18
OUTA2
19
SRA
Ground. (All ground pins are internally connected to the frame of the
device).
Output1 of full bridge 1
Enable (Low active)
Output1of full bridge 2
Current sense resistor of the chopper regulator for OUTB
Output 2 of full bridge 2
Output of full bridge 1
Current sense resistor of the chopper regulator for OUTA
Doc ID 5198 Rev 10
7/29
Electrical specifications
L9935
3
Electrical specifications
3.1
Absolute maximum ratings
Table 3.
Absolute maximum ratings
Symbol
VS
VSPulsed
Parameter
Value
Unit
DC supply voltage
-0.3 to 35
V
Pulsed supply voltage T < 400 ms
-0.3 to 40
V
internally clamped to VS
or GND depending on the
current direction
VOUT (Ai/Bi)
Output voltages
IOUT (Ai/Bi)
DC output currents
Peak output currents (T/tp 10)
VSRA/SRB
VCC
VCDRV
1.2
2.5
A
A
Sense resistor voltages
-0.3 to 6.2
V
Logic supply voltages
-0.3 to 6.2
V
Charge pump buffer voltage versus VS
-0.3 to 10
V
-2 to 8
V
-0.3 to VCC+0.3
V
VSCK, VSDI,
VCSN, VEN
Logic input voltages
VOSC, VSDO
Oscillator voltage range, logic output
Note:
Note: ESD for all pins, except pins SDO, SRA and SRB, are according to MIL883C, tested at
2kV, corresponding to a maximum energy dissipation of 0.2mJ. SDO, SRA and SRB pins
are tested with 800V.
3.2
Thermal data
Table 4.
Thermal data
Symbol
Rthj-case
Parameter
Typical thermal resistance junction-to-case
Value
Unit
5
°C/W
35
°C/W
8
°C/W
-40 to 150
°C
180
°C
2
Rthj-amb
Typical thermal resistance junction-to-ambient (6 cm
ground plane 35 µm thickness)
Typical thermal resistance junction to ambient (soldered on a
Rthj-amb, FR4 FR 4 board with through holes for heat transfer and external
heat sink applied)
8/29
TS
Storage temperature
TSD
Typical thermal shut-down temperature
Doc ID 5198 Rev 10
L9935
3.3
Electrical specifications
Electrical characteristics
8 V  VS  24 V; -40 °C  Tj  150 °C; 4.5 V  VCC  5.5 V, unless otherwise specified.
Parameters are tested at 125 °C. Values at 140 °C are guaranteed by design and
correlation.
Table 5.
Electrical characteristics
Symbol
Parameter
Test condition
Min.
Typ.
Max.
Unit
Supply
IS85
Total supply current IS+ IVCC
(both bridges Off)
VS = 14 V; EN = HIGH;
TJ  85 °C
-
40
100
A
ISOP
Operating supply current
IOUT Ai/Bi = 0; fOSC = 30 kHz
VS = 14 V
-
4.5
-
mA
ICC
5 V supply current
EN = LOW
-
1.4
10
mA
RDSON of sink transistors
Current bit
-
0.4
0.7

combinations LL, LH, VS 12 V
-
0.4
0.7

RDSON of sink transistors +
RDSON of source transistors
Current bit combinations LL,
LH, VS = 8V
-
1.6
3

VFWD
Forward voltage of the DMOS
body diodes
EN = HIGH; IFWD = 1 A;
VS 12 V
-
1
1.4
V
VREV
Reverse DMOS voltage
EN = LOW IREV = 1 A
-
0.5
0.9
V
Rise and fall time of outputs
OUTAi/Bi
0.1...0.9 VOUTVS= 14 V
Chopping 550 mA
0.3
0.6
1.5
s
12
20
35
mV
160
180
210
mV
270
300
340
mV
Full bridges
ROUT, Sink
ROUT, Source RDSON of source transistors
ROUT8, Sink
tr, tf
Switch Off threshold of the chopper (R1  R2 = 0.33 )
VSRHL
VSRLH
VSRLL
Bit 5, 2 = H; Bit 4, 1 = L
Voltage drops across R1  R2 (1)
(Voltage at Pin SRA or SRB vs. Bit 5, 2 = L; Bit 4, 1 = H
GND)
Bit 5, 4, 2, 1 = L
Enable input EN
VEN High
High input voltage
-
VCC 1.2V
-
-
V
VENlow
Low input voltage
-
-
-
1.2
V
VEN Hyst
Enable hysteresis
-
0.1
-
-
V
IEN High
High input current
VHigh = VCC
-10
0
10
A
IEN Low
Low input current
VLOW = 0V
-3
-10
-30
A
2.6
8
V
-0.3
1
V
1.6
V
Logic inputs SDI. SCK, CSN
VHIGH
High input voltage
VLOW
Low input voltage
VHyst
Hysteresis
EN = LOW
0.8
Doc ID 5198 Rev 10
1.2
9/29
Electrical specifications
Table 5.
L9935
Electrical characteristics (continued)
Symbol
Parameter
Test condition
Min.
Typ.
Max.
Unit
IHIGH
High input current
VHigh = VCC
-10
0
10
A
ILow
Low input current
VLow = 0 V
-3
-10
-30
A
0.17
VCC
V
Logic outputs (SDO)
VCC-
VSDO,High
High output voltage
ISDO = -1 mA
VCC-1
VSDO,Low
Low output voltage
ISDO = 1 mA
-
0.17
1
V
VOSC, H
High peak voltage
EN = LOW
2.2
2.46
2.6
V
VOSC, L
Low peak voltage
EN = LOW
1
1.23
1.4
V
IOSC
Charging/discharging current
-
45
62
80
A
fOSC
Oscillator frequency
COSC = 1 nF
20
25
31
kHz
tStart
Oscillator startup time
EN = High Low
2/fosc
5/fosc
8/fosc
Oscillator
Thermal protection
Thermal shut-down
-
160
180
200
Temperature
-
-
-
-
TJ-ALM
Thermal pre alarm
-
130
160
-
°C
TMGN
Margin pre alarm/shut-down
-
10
20
30
K
TJ-OFF
1. Currents of combinations LH and LL are sensed at the external resistors. The Current of bit combination HL is sensed
internally and cannot be adjusted by changing the sense resistors.
10/29
Doc ID 5198 Rev 10
°C
L9935
Application hints
4
Application hints
Figure 3.
General application circuit proposal
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C1 and C2 should be placed as close to the device as possible. Low ESR of C2 is
advantageous. Peak currents through C1 and C2 may reach 2 A. Care should be taken that
the resonance of C1, C2 together with supply wire inductances is not the chopping
frequency or a multiple of it.
Doc ID 5198 Rev 10
11/29
Functional description
L9935
5
Functional description
5.1
Basic structure
The L9935 is a dual full bridge driver for inductive loads with a chopper current regulation.
Outputs A1 and A2 belong to full bridge A Outputs B1 and B2 belong to full bridge B.
The polarity of the bridges can be controlled by bit0 and bit3 (for full bridge A, bit3, for full
bridge B, bit0). Bit5, bit4 (for full bridge A) and bit2, bit1 (for full bridge B) control the
currents. Bit3 high leads to output A1 high. Bit0 high leads to output B1 high.
Current setting Table 6 using a 0.33  sense resistor.
Table 6.
Current setting
bit5, bit2
bit4, bit1
IQX (Typ.)
IRX/max
Remark
H
H
0
0%
-
H
L
60 mA
-
internally sensed
L
H
550 mA
61 %
-
L
L
900 mA
100 %
-
Figure 4.
Typical average load current dependence on RSense
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12/29
Doc ID 5198 Rev 10
2
7
'!0'03
L9935
5.2
Functional description
Full bridge function
Figure 5.
Displays a full bridge including the current sense circuit.
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5.2.1
No current
Bit 5, bit 4 (corresponding bit 2 and bit1 for bridge B) both are HIGH, the current logic will
inhibit all drivers D11, D12, D21, D22 turning off M11, M12, M21, M22 independently from the
signal of the current sense comparator comp 1.
5.2.2
Turning on
Changing bit 5 or bit 4 or both to LOW will turn on either M11 and M22 or M21 and M12
(depending on the phase signal bit 3). Current will start to flow through the load. The current
will be sensed by the drop across R1.
The threshold of the comparator comp 1 depends on the current settings of bit 5 and bit 4.
The current will rise until it exceeds the turn off threshold of comp 1.
5.2.3
Chopping
Exceeding the threshold of comp 1 the drive logic will turn off the sink transistor (M12 or
M22). The sink transistor periodically is turned on again by the oscillator. Immediately after
turning on M12 or M22 the comparator comp 1 will be inhibited for a certain time to blank
switch over spikes caused by capacitive load components up to 5 nF.
Turning off for example M12 will yield a flyback current through D11. (So now the free
wheeling current flows through M21, the load and D11).
This leads to a slow current decay during flyback. Maximum duty cycles of more than 85%
(at fOSC = 25 kHz) are possible. In this case current flows of both bridges will overlap (not
shown in Figure 7).
Doc ID 5198 Rev 10
13/29
Functional description
5.2.4
L9935
Reversing phase
Suppose the current flowed via M21, the load and M12 before reversing phase. Reversing
phase M21 and M12 will be turned off. So now the current will flow through D22, the load and
D11. This leads to a fast current decay.
5.2.5
Chopper control by oscillator
Both chopping circuits work with offset phase. One chopper will switch on the bridge at the
maximum voltage of the oscillator while the other chopper will switch on the bridge at
minimum voltage of the oscillator.
MS1 and MS2 blank switching spikes that could lead to errors of the current control circuit.
Figure 6.
Principal chopper control circuit
-3
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14/29
Doc ID 5198 Rev 10
'!0'03
L9935
Functional description
Figure 7.
Pulse diagram to explain offset chopping
6/3#
CURRENT
THRESHOLD
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CURRENT
THRESHOLD
632"
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Using offset chopping the changes of the supply current remain half as large as using non
offset chopping.
Turning off the oscillator for example by shorting pin OSC to ground will hinder turning on of
the bridges anymore after the comparators have generated a turn off signal.
External clocking is possible overdrives the charge and discharge currents of the oscillator
for example with a push pull logic gate. So several devices can be synchronized.
5.3
Protection and diagnosis functions
The L9935 provides several protection functions and error detection functions. Current
limitation usually is customer defined by the external current sense resistors. The current
sensed there is used to regulate the current through the stepper motor windings by pulse
width modulation. This PWM regulation protects the sink transistors. The source transistors
are protected by an internal overcurrent shut down turning off the source transistors in case
of overload.
Overload detection of the source transistor will turn off the bridge and set the corresponding
error flag.
To turn on the bridge again a new byte must be written into the interface. (Rising slope of
CSN resets the overload error flag).
Both bridges use the same flags. To locate which bridge is affected by an error the bridges
can be tested individually (One bridge just is turned off to check for the error in the other
bridge).
5.4
Short from an output to the supply voltage VS
The current will be limited by the pulse width modulator. The sink transistor will turn off again
after some microseconds. The transistor will periodically be turned on again by the oscillator
8 times. After having detected short 8 times the low side transistor will remain off until the
Doc ID 5198 Rev 10
15/29
Functional description
L9935
next data transfer took place. After detection of a short to VS we suggest to turn off the
corresponding bridge to reduce power dissipation for at least 1ms.
5.5
Diagnosis of a short to VS
During the short current through the sink transistor will rise more rapidly than under normal
load conditions. Reaching a peak current of 1.5 times the maximum PWM current between
typically 2 µs and 5 µs
after turn on will be detected as a short to VS.
Detecting a short the low side transistor will try to turn on again the next 7 trigger pulse of
the oscillator.
Simultaneously the error flag will updated on each pulse.
Figure 8.
Normal PWM current versus short circuit current and detection of short
to VS
)1SHORTTHRESHOLD
07-THRESHOLD
T
T/. TSHORT T07-
T/. TSHORT T07-
T/.
TSHORT T07-
07-DETECTION
SIGNALINTERNAL
T/.
TSHORT T07-
T
3HORTDETECTION
SIGNALINTERNAL
T
%RROR
T
TONTURNONOFTHESINKTRANSISTOR
TONTTSHORTACTIVATIONOFSHORTTHRESHOLD
TONTDELAYT07-ACTIVATIONOF07-THRESHOLD
'!0'03
Between ton and tshort the over current detection is totally blanked.
Between tshort and tPWM the current threshold is set to 1.5 times the maximum PWM current
(1.5 times the current of current setting LL).
Overcurrent now will set the error flag.
After tPWM the current threshold is the nominal PWM current set by the external resistor.
Exceeding this current will just turn off the sink transistor. This is considered as normal
operation. The error flag is detached from the comparator after tPWM so no error flag is set
during normal pulse width modulation.
16/29
Doc ID 5198 Rev 10
L9935
5.6
Functional description
Short from an output to ground
The current through the short will be detected by the protection of the source transistor. The
source transistor will turn off exceeding a current of typically 1.8 A. Minimum overload
detection current is 1.2 A. To obtain proper current regulation (by the sink transistors and not
by source transistor shut down) the maximum current of the PWM regulator should be set to
a maximum value of 1.1 A.
5.7
Diagnosis of a short to ground
Detecting an overload will set an overcurrent error (Error2 = LOW) (bit6). To reset the error
flag a new byte must be written into the interface. (Reset of the error flag takes place at the
rising slope of CSN).
5.8
Shorted load
With a shorted load both, the sink- and the source protection or the PWM alone will
respond. In either case there will be no flyback pulse.
5.9
Diagnosis of a shorted load
Shorting the load two events may take place:
–
overload (of the high side transistor) while low side transistor overcurrent is
detected will set the following combinations:
bit6 = LOW
bit7 = HIGH
–
5.10
overload is marginal. So the low side driver may turn off before overload is
detected. This leads to the combination bit6 = HIGH and bit7 = LOW.
Open load
An open load will not lead to any flyback pulses. Error detection will take advantage of the
flyback pulse. Missing the flyback pulse after reversing the polarity of a motor winding bit7
will become LOW.
Open load will not be tested in the low current mode (current bits HL) to avoid the risk of
instable diagnosis at low flyback currents. Open load immediately after reset or power down
may on random be detected in the low current mode too. This diagnosis however will not
persist longer than 8 changes of polarity.
We strongly suggest to test open load at a high current mode (combination LL).
While circuit clock speed passes the stepper motor resonant points during
acceleration/deceleration phase, it can happen that flyback energy is temporarily insufficient
for a proper open load detection. Under specific circumstances, pending on motor and load
characteristics, this could lead to sporadic faulty open load error messages despite proper
system operation. The recommended solution is an appropriate software filter approach.
A detailed description is available in the application note AN2378 on www.st.com.
Doc ID 5198 Rev 10
17/29
Functional description
5.10.1
L9935
Over temperature pre alarm
Typically 20K before thermal shut down takes place an over temperature pre alarm (bit7 and
bit6 low) takes place. Typically over temperature pre alarm temperature is between 150 °C
and 160 °C.
5.11
Application hints using a high resistive stepper motor
The L9935 was originally targeted on stepper chopping stepper motor application with
typical resistances of 8..12 . Using motors with higher resistance will work too but
diagnosis behavior will slightly change. This paragraph shows the details that should be
taken in account using diagnosis for high resistive motors.
5.11.1
Startup behavior
The device has simple digital filter to avoid triggering diagnosis at a single event that could
be random noise. This digital filter needs 4 chopping pulses to settle. Using a high resistive
motor this chopping does not take place. Instead the digital filter samples each time a
polarity change takes place. So the first three response telegrams after reset may show an
’open load’ error.
Table 7.
High and low resistive motor (error bits)
High resistive motor
(error bits)
Low resistive motor
(error bits)
-
-
telegram (550 mA or 900 mA)
HH
HH
Reverse phase (550 mA or 900 mA)
XH
HH
Reverse phase (550 mA or 900 mA)
XH
HH
Any data
XH
HH
Any data
HH
HH
Input data
Standby
1st
H means check for HIGH at the error bits.
X means don’t care because filter is not yet settled.
Using 75 mA chopping immediately after stand by:
The high resistive motor can be forced to chopping operation in the low current range. This
leads to the same behavior as using a low resistive motor.
Short to VS detection using high resistive motors:
The short to VS flag is overwritten each time the chopper comparator responds. Having
detected a short this flag only can be reset by reaching chopping operation or resetting the
circuit (ENN=1). For a high resistive motor this leads to the following consequence: Once a
short to VS is detected the error flag will persist even if the short is removed again until
either a reset (ENN=1) or chopping (for example in 75mA mode) has taken place. We
suggest to return to operation once a short to VS was detected by using the low current
mode to reset the flag.
18/29
Doc ID 5198 Rev 10
L9935
5.12
Functional description
Limitation of the diagnosis
The diagnosis depends on either detecting an overcurrent of more than typically 1.8 A
through the source transistor or on not detecting a flyback pulse, or on detecting severe
overcurrents of the sink transistor immediately after turn on.
●
Small currents bypassing the load will not be detected.
●
In the low current range (hold current) the flyback pulse (especially commutating
against the supply voltage after changing phase) may (depending on the inductivity of
the stepper motor windings) be too short to be detected correctly. For this reason
diagnosis using the flyback pulse is blanked at phase reversal at hold current.
●
In the low current range (hold current) the current capability of the bridge is reduced on
purpose. Short to VS may not be detected. In stead the bridge may just chop like
normal operation.
●
Flyback pulse detection is not blanked during PWM regulation at hold current (here
commutation voltage is less than 1V thus providing a longer pulse duration.) This
however should be taken in account using stepper motors with low inductivity (less than
0.5mH). Using motors with such a low inductivity the flyback voltage in hold mode may
decay too fast.
●
Motors with extremely low ohmic resistance tend to pump up the current because
current decay during flyback approaches zero while at bridge turn on the current will
increase. This may lead to overcurrent detection. We suggest to use stepper motors
with an ohmic resistance of approximately 3  or more.
Partial shorts of windings or shorts of stepper motors with coils in series may still yield a
flyback pulses that are accepted by the diagnosis as a proper signal.
Table 8.
Diagnosis description - bit7 and bit6
Error 1 bit7 Error 2 bit6
Description
H
H
Normal operation
L
H
Short to VS (sink overload immediately after turn on) shorted load (no
flyback) open load (no flyback)
H
L
short to gnd (source overload, missing flyback is masked)
L
L
over temperature pre alarm
At stepping rates faster than 1ms/data transfer error flags indicating a short should be used
to initiate a pause of at least 1ms to allow the power bridges to cool down again.
5.13
Serial data interface (SPI)
The serial data interface itself consists of the pins SCL (serial clock), SDI (serial data input)
and SDO (serial data output).
To especially support bus controlled applications the additional signals EN (chip enable not)
and CSN (chip select not) are available.
Doc ID 5198 Rev 10
19/29
Functional description
5.13.1
L9935
Startup of the serial data interface
Falling slope of EN activates the device. After ten.sck the device is ready to work.
Falling slope of CSN indicates start of frame. Data transfer (reading SDI into the register)
takes place at the rising slopes of SCK.
Data transfer of the register to SDO takes place at the falling slope of SCK.
Rising slope of CSN indicates end of frame. At the end of frame data will only be accepted if
modulo 8 bit (modulo 8 falling slopes to SCK) have been transferred. If this is not the case
the input will be ignored and the bridges will maintain the same status as before.
SDO is a tristate output.
SDO is active while CSN = LOW, while CSN = HIGH SDO is high resistive.
Figure 9.
SPI data/clock timing
TEN?SCK
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20/29
Doc ID 5198 Rev 10
L9935
5.14
Functional description
Test condition for all propagation times
Unless otherwise specified) HIGH  3 V; LOW  0.8 V; tr, tf = 10 ns;
Enable: ENN Low < 0.8 V, ENN High > VCC -0.8 V
Table 9.
Test condition for all propagation times
Symbol
fSCLK
Parameter
Test conditions
Min.
Typ.
Max.
Unit
SCK-Frequency
-
DC
-
2MHz
-
t1
SCK stable before and after
CSN = 0
-
100
-
-
ns
tch
Width of SCK high pulse
-
200
-
-
ns
tcl
Width of SCK low pulse
-
200
-
-
ns
tsu
SDI setup time
-
80
-
-
ns
tsh
SDI hold time
-
80
-
-
ns
td
SDO delay time (CL = 50pF)
-
-
100
-
ns
tzc
SDO high Z CSN high
-
-
100
-
ns
Setup time ENABLE to SCK
HIGH > VCC-1.2 V
30
-
-
s
-
2(1)
-
s
ten_sck
tpd
Propagation delay SPI to output
QXX
1. Measured at a transition from High impedance (Bridge off) to bridge on. (Reversing polarity takes about 1ms longer
because the bridge first turns off before turning on in reverse direction).
Table of bits
bit5,bit4: current range of bridge A (Outputs A1 and A2)
bit3:
polarity of bridge A
bit2,bit1: current range of bridge B (Outputs B1 and B2)
bit0:
polarity of bridge B
bit7,bit6:
Error1 and Error 2
Doc ID 5198 Rev 10
21/29
Functional description
5.15
L9935
Cascading several devices
Cascading several devices can be done using the SDO output to pass data to the next
device. The whole frame now consists of n byte. n is the number of devices used.
Figure 10. Cascading several stepper motor drivers
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Figure 11. Control sequence for 3 Stepper motor drivers
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Figure 12. Paralleling several devices
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Here usually only one stepper motor driver is selected at a time while all others are
deselected.
22/29
Doc ID 5198 Rev 10
L9935
Functional description
5.16
Application information
For driving a stepper motor we suggest to use the following codes. The columned ’SDO
correct’ shows the data returned at SDO in correct function. The columns presented under
’Error cases’ display the diagnosis bits if errors are detected.
Examples of control sequences.
Table 10.
Full step mode control sequences and diagnosis response
SDO
correct
SDI
Error cases and SDObit7, bit6
Fault
A
bit
-
-
76543210 76543210
Command/response
XX111111
XX011011
XX010011
XX010010
XX011010
XX011011
XX010011
XX010010
XX011010
O
P
E
N
76
B
O
P
E
N
76
A1
A2
B1
B2
S
H
O
R
T
S
H
O
R
T
S
H
O
R
T
S
H
O
R
T
VS
VS
VS
VS
76
76
76
76
A1
A2
B1
B2
(1)
(1)
(1)
(1)
S
H
O
R
T
S
H
O
R
T
S
H
O
R
T
S
H
O
R
T
therm.
therm.
alarm
shut down
(reset
operating
codes)
76
76543210
GND GND GND GND
76
76
76
76
SDO present last data or 11111111 in case prev. state was standby
11111111
11011011
11010011
11010010
11011010
11011011
11010011
11010010
11
11
01
11
01
11
01
11
11
11
11
01
11
01
11
01
11
11
01
01
01
11
01
01
11
01
01
11
01
01
01
11
11
11
11
01
01
01
11
01
11
01
01
01
11
01
01
01
11
10
01
11
10
10
01
11
11
11
10
10
01
11
10
10
11
10
10
01
11
10
10
01
11
11
11
10
10
01
11
10
00
00
00
00
00
00
00
00
00111111
00111111
00111111
00111111
00111111
00111111
00111111
00111111
1. Motor resistance approximately 10 and VS = 12V. So a short to ground only is detected on one branch of the bridge.
Lower resistivity of the motor may lead to detection of short to ground on both branches of the bridge leading to code 10 on
all steps.
These sequences are intended to give the user a good starting point for his software
development. Besides these two there are further possibilities how to implement control
sequences for this device (other currents, quarters step etc.).
Double errors: Double errors will create composite codes by an AND operation between
columns of the same dominance. Open and short to VS are the least dominant error codes.
(first 6 error code columns). Short to ground is the second dominant error code. detection of
short to gnd will overwrite error codes of the least dominant kind (open, short to VS).
Temperature pre alarm and thermal shut down are the most dominant error codes. Thermal
pre alarm returns error code 00 but the device still is working and returns the appropriate
operation code (bits 0..5).
Thermal shut down returns error code 00 and turns off the device. The opcode returned
corresponds the action eventually performed (bit 0..5 become 1).
For example open bridge A and simultaneously open bridge B will lead to error code 01 by
performing an AND operation between the two corresponding columns.
Doc ID 5198 Rev 10
23/29
Functional description
Table 11.
L9935
Half step mode control sequences and diagnosis response
SDI
SDO
Error cases and SDObit7, bit6
-
-
O
P
E
N
B
O
P
E
N
A1
A2
B1
B2
S
H
O
R
T
S
H
O
R
T
S
H
O
R
T
S
H
O
R
T
VS
VS
VS
VS
A1
A2
B1
B2
(1)
(1)
(1)
(1)
S
H
O
R
T
S
H
O
R
T
S
H
O
R
T
S
H
O
R
T
therm.
therm.
alarm
shut down
(reset
operating
codes)
GND GND GND GND
bit
76543210 76543210
76
76
76
76
76
76
76
76
76
76
76
76543210
Command/response
Fault
A
XX111111
XX011111
XX011111
XX011111
XX011011
XX111011
XX010011
XX010111
XX010010
XX110010
XX011010
XX011110
XX011011
XX111011
XX010011
XX010111
XX010010
XX110010
11
11
11
11
11
01
11
11
11
01
11
11
11
01
11
11
11
11
11
11
11
11
11
11
01
11
11
11
01
11
11
11
01
11
11
11
11
11
11
01
01
01
01
01
11
11
01
01
01
01
01
11
01
01
01
01
01
11
11
11
01
01
01
01
01
11
11
11
11
11
11
11
11
11
11
01
01
01
01
01
11
11
11
01
01
11
11
11
11
01
01
01
01
11
11
11
01
01
01
01
01
11
11
10
10
10
10
01
11
11
11
11
10
01
10
01
11
11
11
11
11
11
11
11
11
10
10
10
01
11
11
11
11
10
10
10
11
11
11
11
10
10
10
01
11
11
11
11
10
10
10
01
11
11
11
11
11
11
11
11
11
10
10
10
01
11
11
11
11
10
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00111111
00111111
00111111
00111111
00111111
00111111
00111111
00111111
00111111
00111111
00111111
00111111
00111111
00111111
00111111
00111111
00111111
previous code
11111111
11011111
11011111
11011111
11011111
11011011
11111011
11010011
11010111
11110010
11011010
11011110
11011011
11111011
11010011
11010111
11010010
1. Motor resistance approximately 10 and VS = 12V. So a short to ground only is detected on one branch of the bridge.
Lower resistivity of the motor may lead to detection of short to ground on both branches of the bridge leading to code 10 on
all steps.
24/29
Doc ID 5198 Rev 10
L9935
5.17
Functional description
Electromagnetic emission classification (EME)
Electromagnetic emission classes presented below are typical data found on bench test. For
detailed test description please refer to ’Electromagnetic Emission (EME) Measurement of
Integrated Circuits, DC to 1GHz’ of VDE/ZVEI work group 767.13 and VDE/ZVEI work group
767.14 or IEC project number 47A 1967Ed. This data is targeted to board designers to allow
an estimation of emission filtering effort required in application.
Table 12.
Electromagnetic emission
Pin
EME class
Remark
GND
E
10
0
1 test
VCC
E
-
e
Blocked with 100nF close in to the device
EN. SDI, CSN, CSK, SDO in
tristate
K
-
h
-
SDO
G
-
f
SDO in low-Z state, no data transfer
Power output A1, A2, B1, B2
E
5
f
Sourcing output
Power output A1, A2, B1, B2
-
6
f
Sinking output in chopping mode
fosc = 20 kHz
Electromagnetic emission is not tested in production.
Figure 13. State diagram
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Return to standby is possible from every state
Reversing polarity in low current mode no flyback check will be performed.
Doc ID 5198 Rev 10
25/29
Functional description
L9935
Figure 14. EMC compatibility for L9935
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26/29
Doc ID 5198 Rev 10
L9935
6
Package information
Package information
In order to meet environmental requirements, ST offers these devices in different grades of
ECOPACK® packages, depending on their level of environmental compliance. ECOPACK®
specifications, grade definitions and product status are available at: www.st.com.
ECOPACK® is an ST trademark.
Figure 15. PowerSO20 mechanical data and package dimensions
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Doc ID 5198 Rev 10
27/29
Revision history
7
L9935
Revision history
Table 13.
28/29
Document revision history
Date
Revision
Changes
13-Apr-2003
6
Initial release.
02-Aug-2006
7
Updated at the new corporate template.
Corrected the Figure 14.
11-Dec-2008
8
Updated Figure 2: Pin connection (top view) on page 7.
Updated Section 6: Package information on page 27.
04-Apr-2011
9
Updated Section 5.10: Open load on page 17.
18-sEP-2013
10
Updated Disclaimer.
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