Ordering number : ENA1674A
LV8712T
Bi-CMOS LSI
PWM Constant-Current Control
Stepping Motor Driver
http://onsemi.com
Overview
The LV8712T is a stepping motor driver of the micro-step drive corresponding to supports 2W 1-2 phase excitation. It
is the best for the drive of the stepping motor for a scanner and a small printer.
Features
• Single-channel PWM constant-current control stepping motor driver incorporated.
• Excitation mode can be set to 2-phase, 1-2 phase, W1-2 phase , or 2W1-2 phase
• Microstep can control easily by the CLK-IN input.
• Power-supply voltage of motor
: VM max = 18V
• Output current
: IO max = 0.8A
• Output ON resistance
: RON = 1.1Ω (upper and lower total, typical, Ta = 25°C )
• A thermal shutdown circuit and a low voltage detecting circuit are built into.
Specifications
Absolute Maximum Ratings at Ta = 25°C
Parameter
Symbol
Conditions
Motor supply voltage
VM max
Logic supply voltage
VCC max
Output peak current
IO peak
Each 1ch, tw ≤ 10ms, duty 20%
Output continuousness current
IO max
Each 1ch
Logic input voltage
VIN
Allowable power dissipation
Pd max
Operating temperature
Storage temperature
Ratings
Unit
18
V
6
V
1.0
A
800
mA
-0.3 to VCC + 0.3
V
1.35
W
Topr
-20 to +85
°C
Tstg
-55 to +150
°C
*
* Specified circuit board : 57.0mm×57.0mm×1.7mm, glass epoxy 2-layer board.
Stresses exceeding Maximum Ratings may damage the device. Maximum Ratings are stress ratings only. Functional operation above the Recommended Operating
Conditions is not implied. Extended exposure to stresses above the Recommended Operating Conditions may affect device reliability.
Semiconductor Components Industries, LLC, 2013
June, 2013
20211 SY/51210 SY 20100216-S00005 No.A1674-1/14
LV8712T
Allowable Operating Ratings at Ta = 25°C
Parameter
Symbol
Motor supply voltage range
VM
Logic supply voltage range
VCC
Logic input voltage
VIN
VREF input voltage range
VREF
Conditions
Ratings
Unit
4 to 16
V
2.7 to 5.5
V
-0.3 tp VCC+0.3
V
0 to VCC-1.8
V
Electrical Characteristics at Ta = 25°C, VM = 12V, VCC = 3.3VVREF = 1.0V
Parameter
Symbol
Ratings
Conditions
min
Standby mode current drain
Current drain
typ
IMstn
PS = “L”, no load
1
μA
ICCstn
PS = “L”, no load
1
μA
IM
PS = “H”, no load
0.3
0.5
0.7
mA
0.9
1.3
1.7
mA
ICC
PS = “H”, no load
Thermal shutdown temperature
TSD
Design guarantee
180
Thermal hysteresis width
ΔTSD
Design guarantee
40
VCC low voltage cutting voltage
VthVCC
Low voltage hysteresis voltage
VthHIS
REG5 output voltage
Vreg5
IO = -1mA
Output on resistance
RonU
2.7
V
100
130
160
mV
4.5
5
5.5
V
IO = -800mA, Source-side on resistance
0.78
1.0
Ω
0.32
0.43
Ω
10
μA
1.0
1.2
V
IO = 800mA, Sink-side on resistance
IOleak
VO = 15V
Diode forward voltage
VD
ID = -800mA
IINL
VIN = 0.8V
4
8
12
μA
IINH
VIN = 3.3V
22
33
45
μA
Logic high-level input voltage
VINH
Logic low-level input voltage
VINL
VREF input current
IREF
VREF = 1.0V
Vtdac0_2W
Step 0 (When initialized : channel 1
2W1-2-phase
comparator
drive
°C
2.4
RonD
Current setting
°C
2.1
Output leakage current
Logic pin input current
Unit
max
2.0
V
0.8
V
μA
-0.5
0.191
0.2
0.209
V
comparator level)
threshold
Vtdac1_2W
Step 1 (Initial state+1)
0.187
0.196
0.205
V
voltage
Vtdac2_2W
Step 2 (Initial state+2)
0.175
0.184
0.193
V
Vtdac3_2W
Step 3 (Initial state+3)
0.158
0.166
0.174
V
Vtdac4_2W
Step 4 (Initial state+4)
0.132
0.140
0.148
V
Vtdac5_2W
Step 5 (Initial state+5)
0.102
0.110
0.118
V
Vtdac6_2W
Step 6 (Initial state+6)
0.068
0.076
0.084
V
(current step
switching)
W1-2-phase
Vtdac7_2W
Step 7 (Initial state+7)
0.032
0.040
0.048
V
Vtdac0_W
Step 0 (When initialized : channel 1
0.191
0.200
0.209
V
Vtdac2_W
Step 2 (Initial state+1)
0.175
0.184
0.193
V
Vtdac4_W
Step 4 (Initial state+2)
0.132
0.140
0.148
V
Vtdac6_W
Step 6 (Initial state+3)
0.068
0.076
0.084
V
Vtdac0_H
Step 0 (When initialized : channel 1
0.191
0.200
0.209
V
Step 4 (Initial state+1)
0.132
0.140
0.148
V
Step 4' (When initialized : channel 1
0.191
0.200
0.209
V
drive
1-2 phase drive
comparator level)
comparator level)
Vtdac4_H
2 phase drive
Vtdac4_F
comparator level)
Current setting comparator
Vtatt00
ATT1 = L, ATT2 = L
0.191
0.200
0.209
V
threshold voltage
Vtatt01
ATT1 = H, ATT2 = L
0.152
0.160
0.168
V
(current attenuation rate switching)
Chopping frequency
CHOP pin threshold voltage
Vtatt10
ATT1 = L, ATT2 = H
0.112
0.120
0.128
V
Vtatt11
ATT1 = H, ATT2 = H
0.072
0.080
0.088
V
Fchop
Cchop = 220pF
36
45
54
kHz
VCHOPH
0.6
0.7
0.8
V
VCHOPL
0.17
0.2
0.23
V
7
10
13
μA
250
400
mV
CHOP pin charge/discharge current
Ichop
MONI pin saturation voltage
Vsatmon
Imoni = 1mA
No.A1674-2/14
LV8712T
Package Dimensions
unit : mm (typ)
3260A
Pd max - Ta
1.5
6.5
Allowable power dissipation, Pd max - W
1.35
0.5
6.4
13
4.4
24
12
1
0.5
0.15
0.22
0.08
1.2max
(1.0)
(0.5)
1.0
0.70
0.5
Specified circuit board :
57.0 × 57.0 × 1.7mm3
2-layer glass epoxy board
0
- 20
0
20
40
60
80
100
Ambient temperature, Ta - C
SANYO : TSSOP24(225mil)
FR
OUT1A
PGND
RNF1
OUT1B
VM
OUT2A
RNF2
OUT2B
PGND
MD1
MD2
Pin Assignment
24
23
22
21
20
19
18
17
16
15
14
13
1
2
3
4
5
6
7
8
9
10
11
12
RST
OE
REG5
PS
MONI
VREF
STEP
ATT1
ATT2
CHOP
VCC
GND
LV8712T
No.A1674-3/14
+
-
+
-
GND
VREF
VCC
REG5
LVS
TSD
+
-
PS
Start
circuit
Attenuator
(100%/80%
/60%/40%)
CHOP ATT1 ATT2
Oscillation
circuit
1/5
Standard
voltage
VM-5V
standard voltage
Output preamplifier stage
VM
Output preamplifier stage
Output preamplifier stage
OUT2A
MD2
FR
+
RNF2
Current
selection
(2W1-2/
W1-2/1-2/2)
OUT2B
STEP RST OE
Output control logic
MD1
OUT1B
Current
selection
(2W1-2/
W1-2/1-2/2)
+
OUT1A
Output preamplifier stage
RNF1
MONI
PGND
LV8712T
Block Diagram
No.A1674-4/14
LV8712T
Pin Functions
Pin No.
Pin Name
Pin Functtion
1
RST
Excitation reset signal input pin.
2
OE
Output enable signal input pin.
7
STEP
STEP signal input pin.
8
ATT1
Motor holding current switching pin.
9
ATT2
Motor holding current switching pin.
13
MD2
Excitation mode switching pin 2.
14
MD1
Excitation mode switching pin 1.
24
FR
CW / CCW switching signal input pin.
Equivalent Circuit
VCC
GND
4
PS
Power save signal input pin.
VCC
4
GND
16
OUT2B
Channel 2 OUTB output pin.
17
RNF2
Channel 2 current-sense resistor
18
OUT2A
Channel 2 OUTA output pin.
20
OUT1B
Channel 1 OUTB output pin.
21
RNF1
Channel 1 current-sense resistor
VM
connection pin.
20 16
23 18
connection pin.
23
OUT1A
Channel 1 OUTA output pin.Power
21
17
GND
6
VREF
Constant current control reference
voltage input pin.
VCC
6
GND
Continued on next page.
No.A1674-5/14
LV8712T
Continued from preceding page.
Pin No.
3
Pin Name
REG5
Pin Functtion
Internal power supply capacitor
connection pin.
Equivalent Circuit
VM
3
GND
5
MONI
Position detection monitor pin.
VCC
5
GND
10
CHOP
Chopping frequency setting capacitor
connection pin.
VCC
GND
10
No.A1674-6/14
LV8712T
Description of operation
Stepping motor control
(1) Power save function
This IC is switched between standby and operating mode by setting the PS pin. In standby mode, the IC is set to
power-save mode and all logic is reset. In addition, the internal regulator circuit do not operate in standby mode.
PS
Mode
Internal regulator
Low or Open
Standby mode
Standby
High
Operating mode
Operating
(2) The order of turning on recommended power supply
The order of turning on each power supply recommends the following.
VCC power supply order → VM power supply order → PS pin = High
It becomes the above-mentioned opposite for power supply OFF.
However, the above-mentioned is a recommendation, the overcurrent is not caused by not having defended this, and
IC is destroyed.
(3) STEP pin function
Operating mode
Input
PS
STP
Low
*
Standby mode
High
Excitation step proceeds
High
Excitation step is kept
(4) Excitation mode setting function(initial position)
MD1
MD2
Excitation mode
Initial position
Channel 1
Channel 2
Low
Low
2 phase excitation
100%
-100%
High
Low
1-2 phase excitation
100%
0%
Low
High
W1-2 phase excitation
100%
0%
High
High
2W1-2 phase excitation
100%
0%
This is the initial position of each excitation mode in the initial state after power-on and when the counter is reset.
(5) Position detection monitoring function
The MONI position detection monitoring pin is of an open drian type.
When the excitation position is in the initial position, the MONI output is placed in the ON state.
(Refer to "(12) Examples of current waveforms in each of the excitation modes.")
No.A1674-7/14
LV8712T
(6) Reset function
RST
Operating mode
High
Normal operation
Low
Reset state
RST
RESET
STEP
MONI
1ch output
0%
2ch output
Initial position
When the RST pin is set to Low, the excitation position of the output is forcibly set to the initial position, and the
MONI output is placed in the ON state. When RST is then set to High, the excitation position is advanced by the next
STEP input.
(7) Output enable function
OE
Operating mode
Low
Output ON
High
Output OFF
OE
Power save mode
STEP
MONI
1ch output
0%
2ch output
Output is high-impedance
When the OE pin is set High, the output is forced OFF and goes to high impedance.
However, the internal logic circuits are operating, so the excitation position proceeds when the STEP signal is input.
Therefore, when OE is returned to Low, the output level conforms to the excitation position proceeded by the STEP input.
No.A1674-8/14
LV8712T
(8) Forward/reverse switching function
FR
Operating mode
Low
Clockwise (CW)
High
Counter-clockwise (CCW)
FR
CW mode
CCW mode
CW mode
STEP
Excitation position
(1)
(2)
(3)
(4)
(5)
(6)
(5)
(4)
(3)
(4)
(5)
1ch output
2ch output
The internal D/A converter proceeds by one bit at the rising edge of the input STEP pulse.
In addition, CW and CCW mode are switched by setting the FR pin.
In CW mode, the channel 2 current phase is delayed by 90° relative to the channel 1 current.
In CCW mode, the channel 2 current phase is advanced by 90° relative to the channel 1 current.
(9) Setting constant-current control
The setting of STM driver's constant current control is decided the VREF voltage from the resistance connected
between RNF and GND by the following expression.
IOUT = (VREF/5)/RNF resistance
* The above setting is the output current at 100% of each excitation mode.
The voltage input to the VREF pin can be switched to four-step settings depending on the statuses of the two inputs,
ATT1 and ATT2. This is effective for reducing power consumption when motor holding current is supplied.
Attenuation function for VREF input voltage
ATT1
ATT2
Current setting reference voltage attenuation ratio
Low
Low
100%
High
Low
80%
Low
High
60%
High
High
40%
The formula used to calculate the output current when using the function for attenuating the VREF input voltage is
given below.
IOUT = (VREF/5) × (attenuation ratio)/RNF resistance
Example : At VREF of 1.0V, a reference voltage setting of 100% [(ATT1, ATT2) = (L, L)] and an RNF resistance of
0.5Ω, the output current is set as shown below.
IOUT = 1.0V/5 × 100%/0.5Ω = 400mA
If, in this state, (ATT1, ATT2) is set to (H, H), IOUT will be as follows :
IOUT = 400mA × 40% = 160mA
In this way, the output current is attenuated when the motor holding current is supplied so that power can
be conserved.
No.A1674-9/14
LV8712T
(10) Chopping frequency setting
For constant-current control, this IC performs chopping operations at the frequency determined by the capacitor
(Cchop) connected between the CHOP pin and GND.
The chopping frequency is set as shown below by the capacitor (Cchop) connected between the CHOP pin and GND.
Tchop ≈ C × V × 2 / I (s)
V : Width of suresshu voltage, typ 0.5V
I : Charge/discharge current, typ 10μA
For instance, when Cchop is 200pF, the chopping frequency will be as follows :
Fchop ≈ 1 / Tchop (Hz)
(11) Output current vector locus (one step is normalized to 90 degrees)
100.0
θ0
θ4' (2-phase)
θ1
θ2
Channel 1 phase current ratio (%)
θ3
θ4
66.7
θ5
θ6
33.3
θ7
θ8
0.0
0.0
33.3
66.7
100.0
Channel 2 current ratio (%)
Setting current ration in each excitation mode
STEP
2W1-2 phase (%)
Channel 1
W1-2 phase (%)
Channel 2
Channel 1
θ0
100
0
θ1
98
20
θ2
92
38
θ3
83
55
θ4
70
70
θ5
55
83
θ6
38
92
θ7
20
98
θ8
0
100
1-2 phase (%)
Channel 2
Channel 1
100
0
92
38
70
70
38
92
0
100
2-phase (%)
Channel 2
Channel 1
100
0
70
70
0
100
100
Channel 2
100
No.A1674-10/14
LV8712T
(12) Typical current waveform in each excitation mode
2-phase excitation (CW mode)
STEP
MONI
(%)
100
l1
0
-100
(%)
100
I2
0
-100
1-2 phase excitation (CW mode)
STEP
MONI
(%)
100
I1
0
-100
(%)
100
I2
0
-100
No.A1674-11/14
LV8712T
W1-2 phase excitation (CW mode)
STEP
MONI
(%)
100
I1
0
-100
(%)
100
I2
0
-100
2W1-2 phase excitation (CW mode)
STEP
MONI
(%)
100
50
I1
0
-50
-100
(%)
100
50
I2
0
-50
-100
No.A1674-12/14
LV8712T
(13) Current control timing chart(Chopping operation)
(Sine wave increasing direction)
STEP
Set current
Set current
Coil current
Chopping cycle
fchop
BLANKING section
BLANKING section
Current mode CHARGE
SLOW
FAST
CHARGE
SLOW
FAST
(Sine wave decreasing direction)
STEP
Set current
Coil current
Set current
Chopping cycle
fchop
Current mode CHARGE
Chopping cycle
BLANKING section
SLOW
FAST
BLANKING section
Forced CHARGE
section
FAST
CHARGE
BLANKING section
SLOW
In each current mode, the operation sequence is as described below :
• At rise of chopping frequency, the CHARGE mode begins. (The Blanking section in which the CHARGE mode is
forced regardless of the magnitude of the coil current (ICOIL) and set current (IREF) exists for 1μs.)
• The coil current (ICOIL) and set current (IREF) are compared in this blanking time.
When (ICOIL < IREF) state exists ;
The CHARGE mode up to ICOIL ≥ IREF, then followed by changeover to the SLOW DECAY mode, and
finally by the FAST DECAY mode for approximately 1μs.
When (ICOIL < IREF) state does not exist ;
The FAST DECAY mode begins. The coil current is attenuated in the FAST DECAY mode till one cycle of
chopping is over.
Above operations are repeated. Normally, the SLOW (+FAST) DECAY mode continues in the sine wave increasing
direction, then entering the FAST DECAY mode till the current is attenuated to the set level and followed by the SLOW
DECAY mode.
No.A1674-13/14
LV8712T
Application Circuit Example
Logic input
- +
1.0V
Clock input
24
OUT1A
23
REG5
PGND
22
4
PS
RNF1
21
5
MONI
OUT1B
20
6
VREF
VM
19
7
STEP
8
ATT1
RNF2
17
9
ATT2
OUT2B
16
10
CHOP
PGND
15
11
VCC
MD1 14
12
GND
MD2
RST
2
OE
3
LV8712T
Short-circuit state
detection monitor
FR
1
Logic input
+ -
12V
OUT2A 18
M
220pF
3.3V
- +
Logic input
13
The formulae for setting the constants in the examples of the application circuits above are as follows :
Constant current (100%) setting
When VREF = 1.0V
IOUT = VREF/5/RNF resistance
= 1.0V/5/0.51Ω = 0.392A
Chopping frequency setting
Fchop = Ichop/ (Cchop × Vtchop × 2)
= 10μA/ (220pF × 0.5V × 2) = 45kHz
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