LV8772 Motor Driver Application Note

LV8772
Bi-CMOS LSI
PWM Constant-Current Control
Stepper Motor Driver
Application Note
http://onsemi.com
Overview
LV8772 is a micro step drive stepper motor driver corresponding to the 1/16 step resolution. It is most
suitable for the drive of a stepping motor for OA, amusements.
Function
• Single-channel PWM current control stepping motor driver incorporated.
• BiCDMOS process IC
• Low on resistance (total of upper and lower: 0.55Ω, Ta=25°C)
• Micro-step mode can be set to Full-step, Half-step, Quarter-step, or 1/16-step
• Excitation step proceeds only by step signal input
• Motor current selectable in four steps
• Output short-circuit protection circuit incorporated
• Unusual condition warning output pins
• Built-in thermal shutdown circuit
• No control power supply required
Typical Applications
• PPC (Plain Paper Copier)
• LBP (Laser Beam Printer)
• Scanner
• Industrial
• Amusement
• Textile
Semiconductor Components Industries, LLC, 2013
December, 2013
1/33
LV8772 Application Note
Package Dimensions
unit: mm (typ)
3147C
15
12.7
11.2
R1.7
0.4
8.4
28
1
14
20.0
4.0
4.0
26.75
(1.81)
1.78
0.6
1.0
SANYO : DIP28H(500mil)
Pin Assignment
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LV8772 Application Note
Block Diagram
CP2
CP1
VG
OUT1A
RF1
OUT1B VM1
VM2 OUT2A
OUT2B
RF2
VREG5
Output preamplifier stage
MONI
Output preamplifier stage
Output preamplifier stage
Charge pump
PGND
Output preamplifier stage
VM
EMO
Output control logic
Regulator
VREF
Attenuator
(4 levels
selectable)
Microstep mode
selection
Microstep mode
selection
Oscillation
circuit
GND
TSD
LVS
CHOP
ST ATT1 ATT2
MD1
MD2
FR
STEP RST
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LV8772 Application Note
Specifications
Absolute Maximum Ratings at Ta = 25°C
Parameter
Symbol
Conditions
Ratings
Unit
Supply voltage
VM max
VM, VM1, VM2
36
V
Output peak current
IO peak
tw ≤ 10ms, duty 20%, each 1ch
3.0
A
Output current
IO max
each 1ch
2.5
A
Logic input voltage
VIN max
ST, ATT1, ATT2, MD1, MD2, FR, STEP, RST
MONI/EMO input voltage
Vmo/Vemo
Allowable power dissipation
Pd max1
1 unit
3.0
W
Pd max2
*
5.4
W
-0.3 to +6
V
-0.3 to +6
V
Operating temperature
Topr
-20 to +85
°C
Storage temperature
Tstg
-55 to +150
°C
* Specified circuit board: 90.0mm×90.0mm×1.6mm, glass epoxy 2-layer board
Caution 1) Absolute maximum ratings represent the value which cannot be exceeded for any length of time.
Caution 2) Even when the device is used within the range of absolute maximum ratings, as a result of continuous usage
under high temperature, high current, high voltage, or drastic temperature change, the reliability of the IC may
be degraded. Please contact us for the further details.
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.
Recommended Operating Conditions at Ta = 25°C
Parameter
Symbol
Conditions
Ratings
min
typ
Unit
max
Supply voltage range
VM
VM, VM1, VM2
9
32
V
Logic input voltage
VIN
ST, ATT1, ATT2, MD1, MD2, FR, STEP, RST
0
5.5
V
VREF input voltage range
VREF
0
3
V
Electrical Characteristics at Ta = 25°C, VM = 24V, VREF = 1.5V
Parameter
Symbol
Conditions
Ratings
min
typ
Unit
max
Standby mode current drain
IMst
ST = “L”, VM+VM1+VM2
100
400
μA
Current drain
IM
ST = “H”, OE = “L”, with no load, VM+VM1+VM2
3.2
5
mA
VREG5 output voltage
Vreg5
IO = -1mA
4.5
5
5.5
V
Thermal shutdown temperature
TSD
Design guarantee
150
180
200
°C
Thermal hysteresis width
ΔTSD
Design guarantee
40
°C
Continued on next page.
4/33
LV8772 Application Note
Continued from preceding page.
Parameter
Symbol
Conditions
Ratings
min
typ
Unit
max
Motor driver
Output on resistance
Ronu1
IO = 2.5A, Upper-side on resistance
0.3
0.4
Ω
Rond1
IO = 2.5A, Lower-side on resistance
0.25
0.33
Ω
50
μA
1.2
1.4
V
4
8
12
μA
50
70
μA
5.5
V
Output leakage current
IOleak
Diode forward voltage
VD
ID = -2.5A
Logic pin input current
IINL
VIN = 0.8V, ST, ATT1, ATT2, MD1, MD2, FR,
STEP, RST
IINH
VIN = 5V
30
Logic input
high-level
VINH
ST, ATT1, ATT2, MD1, MD2, FR, STEP, RST
2.0
voltage
low-level
VINL
Current setting
1/16 step
Vtdac0_4W
comparator
resolution
0
Step 0 (When initialized : channel 1
0.291
0.8
V
0.3
0.309
V
comparator level)
threshold
Vtdac1_4W
Step 1 (Initial state+1)
0.291
0.3
0.309
V
voltage
Vtdac2_4W
Step 2 (Initial state+2)
0.285
0.294
0.303
V
Vtdac3_4W
Step 3 (Initial state+3)
0.279
0.288
0.297
V
Vtdac4_4W
Step 4 (Initial state+4)
0.267
0.276
0.285
V
Vtdac5_4W
Step 5 (Initial state+5)
0.255
0.264
0.273
V
Vtdac6_4W
Step 6 (Initial state+6)
0.240
0.249
0.258
V
Vtdac7_4W
Step 7 (Initial state+7)
0.222
0.231
0.240
V
Vtdac8_4W
Step 8 (Initial state+8)
0.201
0.21
0.219
V
Vtdac9_4W
Step 9 (Initial state+9)
0.180
0.189
0.198
V
Vtdac10_4W
Step 10 (Initial state+10)
0.157
0.165
0.173
V
Vtdac11_4W
Step 11 (Initial state+11)
0.134
0.141
0.148
V
Vtdac12_4W
Step 12 (Initial state+12)
0.107
0.114
0.121
V
Vtdac13_4W
Step 13 (Initial state+13)
0.080
0.087
0.094
V
Vtdac14_4W
Step 14 (Initial state+14)
0.053
0.06
0.067
V
Vtdac15_4W
Step 15 (Initial state+15)
0.023
0.03
0.037
V
Vtdac0_W
Step 0 (When initialized : channel 1
0.291
0.3
0.309
V
(current step
switching)
Quarter step
resolution
Half step
comparator level)
Vtdac4_W
Step 4 (Initial state+1)
0.267
0.276
0.285
V
Vtdac8_W
Step 8 (Initial state+2)
0.201
0.21
0.219
V
Vtdac12_W
Step 12 (Initial state+3)
0.107
0.114
0.121
V
Vtdac0_H
Step 0 (When initialized : channel 1
0.291
0.3
0.309
V
resolution
comparator level)
Vtdac8_H
Step 8 (Initial state+1)
0.201
0.21
0.219
V
Vtdac8_F
Step 8' (When initialized : channel 1
0.291
0.3
0.309
V
Current setting comparator
Vtatt00
ATT1 = L, ATT2 = L
0.291
0.3
0.309
V
threshold voltage
Vtatt01
ATT1 = H, ATT2 = L
0.232
0.24
0.248
V
Vtatt10
ATT1 = L, ATT2 = H
0.143
0.15
0.157
V
Vtatt11
ATT1 = H, ATT2 = H
0.053
0.06
0.067
V
Chopping frequency
Fchop
Cchop = 180pF
45
55
65
kHz
CHOP pin charge/discharge current
Ichop
7
10
13
μA
Chopping oscillation circuit
Vtup
0.8
1
1.2
V
threshold voltage
Vtdown
0.4
0.5
0.6
VREF pin input current
Iref
VREF = 1.5V
MONI pin saturation voltage
Vsatmon
Imoni = 1mA
Full step
resolution
(current attenuation rate switching)
comparator level)
V
μA
-0.5
400
mV
Charge pump
VG output voltage
VG
Rise time
tONG
Oscillator frequency
Fosc
28
VG = 0.1μF
90
28.7
29.8
V
200
500
μS
125
150
kHz
400
mV
Output short-circuit protection
EMO pin saturation voltage
Vsatemo
Iemo = 1mA
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LV8772 Application Note
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LV8772 Application Note
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LV8772 Application Note
Pin Functions
Pin No.
Pin Name
Pin Function
25
ATT2
Motor holding current switching pin.
24
ATT1
Motor holding current switching pin.
20
RST
RESET input pin.
19
STEP
STEP signal input pin.
18
FR
CW / CCW signal input pin.
17
MD2
Excitation mode switching pin 2.
16
MD1
Excitation mode switching pin 1.
Equivalent Circuit
VREG5
10kΩ
100kΩ
GND
15
ST
Chip enable pin.
VREG5
20kΩ
10kΩ
80kΩ
GND
12
OUT2B
Channel 2 OUTB output pin.
4,11
PGND
Power system ground.
10
VM2
Channel 2 motor power supply
9
RF2
8
OUT2A
Channel 2 OUTA output pin.
7
OUT1B
Channel 1 OUTB output pin.
6
RF1
Channel 1 current-sense resistor
5
VM1
Channel 1 motor power supply pin.
3
OUT1A
Channel 1 OUTA output pin.
connection pin.
Channel 2 current-sense resistor
connection pin.
connection pin.
Continued on next page.
8/33
LV8772 Application Note
Continued from preceding page.
Pin No.
Pin Name
Pin Function
2
VG
Charge pump capacitor connection pin.
1
VM
Motor power supply connection pin.
28
CP2
Charge pump capacitor connection pin.
27
CP1
Charge pump capacitor connection pin.
14
VREF
Constant current control reference
voltage input pin.
Equivalent Circuit
VREG5
500Ω
GND
26
VREG5
Internal power supply capacitor
connection pin.
VM
2kΩ
78kΩ
26kΩ
GND
23
EMO
Output short-circuit state warning output
pin.
21
MONI
VREG5
Position detection monitor pin.
GND
Continued on next page.
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LV8772 Application Note
Continued from preceding page.
Pin No.
22
Pin Name
CHOP
Pin Function
Chopping frequency setting capacitor
connection pin.
Equivalent Circuit
VREG5
500Ω
500Ω
GND
13
GND
Ground.
10/33
LV8772 Application Note
Description of operation
Input Pin Function
The function to prevent including the turn from the input to the power supply is built into each input pin.
Therefore, the current turns to the power supply even if power supply (VM) is turned off with the voltage
impressed to the input pin and there is not crowding.
(1) Chip enables function
This IC is switched between standby and operating mode by setting the ST pin. In standby mode, the IC is
set to power-save mode and all logic is reset. In addition, the internal regulator circuit and charge pump
circuit do not operate in standby mode.
ST
Mode
Internal regulator
Charge pump
Low or Open
Standby mode
Standby
Standby
High
Operating mode
Operating
Operating
STM mode
(1) STEP pin function
STEP input advances electrical angle at every rising edge (advances step by step).
Input
Operating mode
ST
STEP
Low
*
Standby mode
High
Excitation step proceeds
High
Excitation step is kept
STEP input MIN pulse width (common in H/L): 500ns (MAX input frequency: 1MHz)
However, constant current control is performed by PWM during chopping period, which is set by the
capacitor connected between CHOP and GND. You need to perform chopping more than once per step.
For this reason, for the actual STEP frequency, you need to take chopping frequency and chopping
count into consideration.
For example, if chopping frequency is 50kHz (20μs) and chopping is performed twice per step, the
maximum STEP frequency is obtained as follows: f = 1/(20μs×2) = 25kHz.
(2) Input timing
TstepH TstepL
STEP
Tdh
Tds
(md1 step) (step md1)
MD1
Tdh
Tds
(md2 step) (step md2)
MD2
Tdh
Tds
(fr step) (step fr)
FR
TstepH/TstepL : Clock H/L pulse width (min 500ns)
Tds : Data set-up time (min 500ns)
Tdh : Data hold time (min 500ns)
Figure 12. Input timing chart
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LV8772 Application Note
(3) Position detection monitoring function
The MONI position detection monitoring pin is of an open drain type.
When the excitation position is in the initial position, the MONI output is placed in the ON state.
(Refer to "Examples of current waveforms in each of the excitation modes.")
(4) Setting constant-current control reference current
This IC is designed to automatically exercise PWM constant-current chopping control for the motor current
by setting the output current. Based on the voltage input to the VREF pin and the resistance connected
between RF and GND, the output current that is subject to the constant-current control is set using the
calculation formula below:
IOUT = (VREF/5) /RF resistance
* The above setting is the output current at 100% of each excitation mode.
If VREF is open or the setting is out of the recommendation operating range, output current will increase
and you cannot set constant current under normal condition. Hence, make sure that VREF is set in
accordance with the specification.
However, if current control is not performed (if the IC is used by saturation drive) make sure that the setting
is as follows: VREF=5V or VREF=VREG5.
Power dissipation of RF resistor is obtained as follows: Pd=Iout2×RF. Make sure to take allowable power
dissipation into consideration when you select RF resistor.
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
50%
High
High
20%
ATT1
10V/div
50ms/div
ATT2
10V/div
VM=24V
VREF=1.0V
RF=0.22Ω
Motor Current
Iout1
0.5A/div
Iout2
0.5A/div
100%
50%
Figure 13. Attenuation operation
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) /RF resistance
Example: At VREF of 1.0V, a reference voltage setting of 100% [(ATT1, ATT2) = (L, L)] and an RF
resistance of 0.5Ω, the output current is set as shown below.
IOUT = 1.0V/5 × 100%/0.22Ω = 0.91A
If, in this state, (ATT1, ATT2) is set to (H, H), IOUT will be as follows:
IOUT =0.91A × 50% = 455mA
In this way, the output current is attenuated when the motor holding current is supplied so that
power can be conserved.
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LV8772 Application Note
(5) Reset function
RST
Operating mode
Low
Normal operation
High
Reset state
RST
RESET
STEP
MONI
1ch output
0%
2ch output
Initial state
Figure 14. Reset operation
When the RST pin is set to High, the excitation position of the output is forcibly set to the initial state, and
the MONI output is placed in the ON state. When RST is then set to Low, the excitation position is
advanced by the next STEP input.
(6) 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
Figure 15. FR operation
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.
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LV8772 Application Note
(7) 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.
Fchop = Ichop/ (Cchop × Vtchop × 2) (Hz)
Ichop: Capacitor charge/discharge current, typ 10μA
Vtchop: Charge/discharge hysteresis voltage (Vtup-Vtdown), typ 0.5V
For instance, when Cchop is 200pF, the chopping frequency will be as follows:
Fchop = 10μA/ (180pF × 0.5V × 2) = 55 kHz
The higher the chopping frequency is, the greater the output switching loss becomes. As a result, heat
generation issue arises. The lower the chopping frequency is, the lesser the heat generation becomes.
However, current ripple occurs. Since noise increases when switching of chopping takes place, you need to
adjust frequency with the influence to the other devices into consideration. The frequency range should be
between 40kHz and 125kHz.
(8) Blanking period
If, when exercising PWM constant-current chopping control over the motor current, the mode is switched
from decay to charge, the recovery current of the parasitic diode may flow to the current sensing resistance,
causing noise to be carried on the current sensing resistance pin, and this may result in erroneous
detection. To prevent this erroneous detection, a blanking period is provided to prevent the noise occurring
during mode switching from being received. During this period, the mode is not switched from charge to
decay even if noise is carried on the current sensing resistance pin.
The blanking time is fixed at approximately 1μs.
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LV8772 Application Note
(9) Output current vector locus (one step is normalized to 90 degrees)
100.0
θ0
θ1
θ8' (2-phase)
θ2
θ3
θ4
θ5
θ6
Channel 1 phase current ratio (%)
θ7
θ8
66.7
θ9
θ 10
θ 11
θ 12
33.3
θ 13
θ 14
θ 15
θ 16
0.0
0.0
33.3
66.7
100.0
Channel 2 current ratio (%)
Figure 16. Current vector position
Setting current ration in each Micro-step mode
STEP
1/16 step (%)
Channel 1
Quarter step (%)
Half step (%)
Full step (%)
Channel 2
Channel 1
Channel 2
Channel 1
Channel 2
100
0
100
0
92
38
70
70
70
70
38
92
0
100
0
100
θ0
100
0
θ1
100
10
θ2
98
20
θ3
96
29
θ4
92
38
θ5
88
47
θ6
83
55
θ7
77
63
θ8
70
70
θ9
63
77
θ10
55
83
θ11
47
88
θ12
38
92
θ13
29
96
θ14
20
98
θ15
10
100
θ16
0
100
Channel 1
Channel 2
100
100
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LV8772 Application Note
(10) Excitation mode setting function
MD1
Low
MD2
Micro-step resolution (Excitation mode)
Low
Full step
Initial position
Channel 1
Channel 2
100%
-100%
100%
0%
100%
0%
100%
0%
(2 phase excitation)
High
Low
Half step
(1-2 phase excitation)
Low
High
Quarter step
(W1-2 phase excitation)
High
High
1/16 step
(4W1-2 phase excitation)
This is the initial position of each excitation mode in the initial state after power-on and when the counter is reset.
(11) Micro-step mode switching operation
When micro-step mode is switched while the motor is rotating, each drive mode operates with the
following sequence.
Clockwise mode
Before the micro-step mode changes
Micro-step mode
Position
1/16 step
Quarter step
Half step
Full step
1/16 step
Position after the micro-step mode is changed
Quarter step
Half step
Full step
θ0-θ1
θ4
θ8
θ8’
θ2-θ3
θ4
θ8
θ8’
θ4-θ5
θ8
θ8
θ8’
θ6-θ7
θ8
θ8
θ8’
θ8-θ9
θ12
θ16
θ8’
θ10-θ11
θ12
θ16
θ8’
θ12-θ13
θ16
θ16
θ8’
θ14-θ15
θ16
θ16
θ8’
θ16
-θ12
-θ8
-θ8’
θ0
θ1
θ8
θ8’
θ4
θ5
θ8
θ8’
θ8
θ9
θ16
θ8’
θ12
θ13
θ16
θ8’
θ16
-θ15
-θ8
-θ8’
θ0
θ1
θ4
θ8
θ9
θ12
θ8’
θ16
-θ15
-θ12
-θ8’
θ8’
θ9
θ12
θ8’
θ16
*As for θ0 to θ16, please refer to the step position of current ratio setting.
If you switch micro-step mode while the motor is driving, the mode setting will be reflected from the next
STEP and the motor advances to the closest excitation position at switching operation.
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LV8772 Application Note
(12) Typical current waveform in each micro-step mode
Full step (CW mode)
STEP
MONI
（％）
I1
100
0
（％）－100
100
I2
0
－100
Figure 17. Current waveform of Full step in CLK-IN
Half step (CW mode)
STEP
MONI
(%)
100
I1
0
－100
(%)
100
I2
0
－100
Figure 18. Current waveform of Half step in CLK-IN
17/33
LV8772 Application Note
Quarter step (CW mode)
STEP
MONI
(%)
100
I1
0
－100
(%)
100
I2
0
－100
Figure 19. Current waveform of Quarter step in CLK-IN
1/16 step (CW mode)
Figure 20. Current waveform of 1/16 step in CLK-IN
18/33
LV8772 Application Note
(13) Current control operation specification
(Sine wave increasing direction)
STEP
Set current
Set current
Coil current
Forced CHARGE
section
Current mode CHARGE
SLOW
FAST
CHARGE
SLOW
FAST
(Sine wave decreasing direction)
STEP
Set current
Coil current
Forced CHARGE
section
Current mode CHARGE
SLOW
Set current
FAST
Forced CHARGE
section
FAST
CHARGE
SLOW
Figure 21. Current control operation
In each current mode, the operation sequence is as described below:
• At rise of chopping frequency, the CHARGE mode begins. (In the time defined as the “blanking time,” the
CHARGE mode is forced regardless of the magnitude of the coil current (ICOIL) and set current (IREF).)
• 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 Triangle 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.
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LV8772 Application Note
(14) Output transistor operation mode
Charge increases
current.
Switch from Charge to
Slow Decay
4.
5. FAST
6.
VM
VM
VM
OFF
OFF
U1
OFF
U2
OUTA
Current regeneration by
Slow Decay
OUTA
L1
L2
RF
OUTB
OF
F
OFF
L2
L1
RF
L2
RF
Current regeneration by
Fast Decay
Switch from Slow Decay to
Fast Decay
U2
OUTA
OF
F
L1
OFF
U1
OUTB
ON
OFF
OFF
U2
OUTB
ON
ON
U1
Switch from Fast Decay to
Charge
Figure 22. Switching operation
This IC controls constant current by performing chopping to output transistor.
As shown above, by repeating the process from 1 to 6, setting current is maintained.
Chopping consists of 3 modes: Charge/ Slow decay/ Fast decay. In this IC, for switching mode (No.2, 4, 6),
there are “off period” in upper and lower transistor to prevent crossover current between the transistors. This
off period is set to be constant (≈ 0.375μs) which is controlled by the internal logic. The diagrams show
parasitic diode generated due to structure of MOS transistor. When the transistor is off, output current is
regenerated through this parasitic diode.
Output Transistor Operation Function
OUTA→OUTB (CHARGE)
Output Tr
U1
U2
L1
L2
OUTB→OUTA (CHARGE)
Output Tr
U1
U2
L1
L2
CHARGE
ON
OFF
OFF
ON
SLOW
OFF
OFF
ON
ON
FAST
OFF
ON
ON
OFF
CHARGE
OFF
ON
ON
OFF
SLOW
OFF
OFF
ON
ON
FAST
ON
OFF
OFF
ON
20/33
LV8772 Application Note
10ms/div
STEP
10V/div
VM=24V
VREF=1.0V
RF=0.22Ω
CHOP=180pF
Motor Current
0.5A/div
CHOP
0.5V/div
Sine wave increasing direction
10μs/div
Sine wave decreasing direction
20μs/div
STEP
10V/div
Set Current
Motor Current
200mA/div
STEP
10V/div
Set Current
CHOP
0.5V/div
Motor Current
200mA/div
CHOP
0.5V/div
Figure 23. Current control operation waveform
Current mode
5μs/div
Motor Current
100mA/div
CHARGE
CHOP
0.5V/div
FAST
Figure 24. Chopping waveform
SLOW
Motor current switches to Fast Decay mode when triangle wave (CHOP) switches from Discharge to Charge.
Approximately after 1μs, the motor current switches to Charge mode. When the current reaches to the setting
current, it is switched to Slow Decay mode which continues over the Discharge period of triangle wave.
21/33
LV8772 Application Note
Output short-circuit protection function
This IC incorporates an output short-circuit protection circuit that, when the output has been shorted by an
event such as shorting to power or shorting to ground, sets the output to the standby mode and turns on the
warning output in order to prevent the IC from being damaged. This function sets the output to the standby
mode for both channels by detecting the short-circuiting in one of the channels.
(1) Output short-circuit detection operation
Short to Power
VM
VM
Tr1
Tr1
Tr3
ON
OUTA
1.High current flows if OUTB short to VM
and Tr4 are ON.
2. If RF voltage> setting voltage, then the
mode switches to SLOW decay.
3.If the voltage between D and S of Tr4
exceeds the reference voltage for 2μs,
short status is detected.
OFF
OUTA
OFF
OUTB
M
Tr2
OFF
Tr3
Tr4
Tr2
ON
ON
OFF
OUTB
M
Tr4
ON
RF
RF
Short-circuit
Detection
Short to GND
Short-circuit
Detection
VM
Tr1
ON
OUTA
Tr3
M
Tr2
OFF
RF
Load short
Short-circuit
Detection
OFF
OUTB
VM
Tr1
ON
OUTA
Tr4
Tr2
ON
OFF
Tr3
M
OFF
OUTB
Tr4
ON
RF
(left schematic)
1.High current flows if OUTA short to
GND and Tr1 are ON
2. If the voltage between D and S of Tr1
exceeds the reference voltage for 2μs,
short status is detected.
(right schematic)
1. Without going through RF resistor,
current control does not operate and
current will continue to increase in
CHARGE mode.
2. If the voltage between D and S of Tr1
exceeds the reference voltage for 2μs,
short status is detected.
1. Without L load, high current flows.
2. If RF voltage> setting voltage, then the
mode switches to SLOW decay.
3. During load short stay in SLOW decay
mode, current does not flow and over
current state is not detected. Then the
mode is switched to FAST decay
according to chopping cycle.
4. Since FAST state is short (≈1μs),
switches to CHARGE mode before short
is detected.
5. If voltage between D and S exceeds
the reference voltage continuously
during blanking time at the start of
CHARGE mode (Tr1), CHARGE state is
fixed (even if RF voltage exceeds the
setting voltage, the mode is not
switched to SLOW decay). After 2us or
so, short is detected.
22/33
LV8772 Application Note
(2) Output short-circuit protection detect current (Reference value)
Short protector operates when abnormal current flows into the output transistor.
Ta = 25°C (typ)
Output Transistor
LV8772
Upper-side Transistor
5.0A
Lower-side Transistor
3.9A
*RF=GND
Figure 25. Detect current vs temperature
23/33
LV8772 Application Note
(3) Output short-circuit protection type
The output short-circuit protection type of LV8772 is the latch type to turn off when the output current
exceeds the detection current and the state is maintained.
The output short-circuit protection circuit is activated in an event of short-circuit in the output pin.
When the short-circuit state continues for a period of time set by the internal timer (approximately 4us), the
output in which short-circuit was first detected are switched to the standby mode. And if the short-circuit
state is still detected, all the outputs of the channel are switched to the standby mode, and the state is held.
This state is released by setting ST to low.
4
Figure 26. Timing chart in latch type
(4) Unusual condition warning output pins (EMO)
This IC is provided with the EMO pin which notifies the CPU of an unusual condition if the protection circuit
operates by detecting an unusual condition of the IC. This pin is of the open-drain output type and when an
unusual condition is detected, the EMO output is placed in the ON (EMO = Low) state.
Furthermore, the EMO pin is placed in the ON state when one of the following conditions occurs.
1. Shorting-to-power, shorting-to-ground, or shorting-to-load occurs at the output pin and the output
short-circuit protection circuit is activated.
2. The IC junction temperature rises and the thermal protection circuit is activated.
24/33
LV8772 Application Note
Charge Pump Circuit
When the ST pin is set high, the charge pump circuit operates and the VG pin voltage is boosted from the
VM voltage to the VM + VREG5 voltage. Because the output is not turned on if VM+4V or more is not
pressured, the voltage of the VG pin recommends the drive of the motor to put the time of tONG or more,
and to begin.
ST
VG pin voltage
VM+VREG5
VM+4V
VM
tONG
Figure 27. VG pin voltage schematic view
VG voltage is used to drive upper output FET and VREG5 voltage is used to drive lower output FET.
Since VG voltage is equivalent to the addition of VM and VREG5 voltage, VG capacitor should allow higher
voltage.
The capacitor between CP1 and CP2 is used to boost charge pump. Since CP1 oscillates with 0V↔VREG5
and CP2 with VM↔VM+VREG5, make sure to allow enough capacitance between CP1 and CP2.
Since the capacitance is variable depends on motor types and driving methods, please check with your
application before you define constant to avoid ripple on VG voltage.
(Recommended value)
VG: 0.1μF
CP1-CP2: 0.1μF
tONG
Startup time with different VG capacitor
50μs/div
ST
5V/div
500μs/div
VG
5V/div
VM+4V
Vout
10V/div
0.1μF /300us
0.22μF /620us
1μF /2.9ms
tONG
VM=24V
CP1-CP2=0.1μF
VG=0.1μF
VM=24V
CP1-CP2=0.1μF
VG=0.1μF/0.22μF/1μF
Figure 28.VG voltage pressure waveform
25/33
LV8772 Application Note
Thermal shutdown function
The thermal shutdown circuit is incorporated and the output is turned off when junction temperature Tj
exceeds 180°C and the abnormal state warning output is turned on. As the temperature falls by hysteresis,
the output turned on again (automatic restoration).
The thermal shutdown circuit does not guarantee the protection of the final product because it operates
when the temperature exceed the junction temperature of Tjmax=150°C.
TSD = 180°C (typ)
ΔTSD = 40°C (typ)
26/33
LV8772 Application Note
Application Circuit Example
• Stepping motor driver circuit
24V
0.1μF
10μF
0.1μF
0.22Ω
M
0.22Ω
1
VM
CP2
2
VG
CP1 27
28
3 OUT1A
VREG5 26
4
PGND
ATT2 25
5
VM1
ATT1 24
6
RF1
EMO 23
7 OUT1B
CHOP 22
8 OUT2A
MONI 21
0.1μF
47KΩ
Short-circuit state
detection monitor
180pF
RF2
RST 20
Position detection
monitor
10 VM2
STEP 19
Clock Input
9
11 PGND
FR 18
12 OUT2B
MD2 17
13 GND
MD1 16
14 VREF
Logic
Input
ST 15
1.5V
The formula for setting the constants in the examples of the application circuits above are as follows:
Constant current (100%) setting
When VREF = 1.5V
IOUT = VREF/5/RF resistance
= 1.5V/5/0.22Ω = 1.36A
Chopping frequency setting
Fchop = Ichop/ (Cchop × Vtchop × 2)
= 10μA/ (180pF × 0.5V × 2) = 55kHz
27/33
LV8772 Application Note
Allowable power dissipation
The pad on the backside of the IC functions as heatsink by soldering with the board. Since the heat-sink
characteristics vary depends on board type, wiring and soldering, please perform evaluation with your board
for confirmation.
Specified circuit board: 90mm x 90mm x 1.6mm, glass epoxy 2-layer board
Substrate Specifications (Substrate recommended for operation of LV8772)
Size
: 90mm × 90mm × 1.6mm (two-layer substrate [2S0P])
Material
: Glass epoxy
28/33
LV8772 Application Note
Evaluation board
LV8772
(90.0mm×90.0mm×1.6mm, glass epoxy 2-layer board)
Bill of Materials for LV8772 Evaluation Board
Designator
Quantity
C1
1
C2
1
C3
1
C4
1
C5
1
R1
1
R2
1
R3
1
R4
1
Description
Capacitor
for Charge
pump
Capacitor
for Charge
pump
VREG5
stabilization
Capacitor
Capacitor to
set
chopping
frequency
VM Bypass
Capacitor
Pull-up
Resistor for
for terminal
MONI
Pull-up
Resistor for
for terminal
EMO
Channel 1
output
current
detective
Resistor
Channel 2
output
current
detective
Resistor
Manufacturer
Manufacturer Part
Number
Substitution
Allowed
Lead
Free
±10%
Murata
GRM188R72A104KA35*
Yes
Yes
0.1µF,
100V
±10%
Murata
GRM188R72A104KA35*
Yes
Yes
0.1µF,
100V
±10%
Murata
GRM188R72A104KA35*
Yes
Yes
±5%
Murata
SUN Electronic
Industries
GRM1882C1H181JA01*
Yes
Yes
Value
Tolerance
0.1µF,
100V
180pF,
50V
10µF,
50V
Footprint
±20%
50ME10HC
Yes
Yes
47kΩ,
1/10W
±5%
KOA
RK73B1JT**473J
Yes
Yes
47kΩ,
1/10W
±5%
KOA
RK73B1JT**473J
Yes
Yes
0.22Ω,
1W
±5%
ROHM
MCR100JZHJLR22
Yes
Yes
0.22Ω,
1W
±5%
ROHM
ON
Semiconductor
MCR100JZHJLR22
Yes
Yes
LV8772
No
Yes
DIP28H
（500mil）
IC1
1
Motor Driver
SW1-SW7
7
Switch
MIYAMA
MS-621C-A01
Yes
Yes
TP1-TP26
26
Test Point
MAC8
ST-1-3
Yes
Yes
29/33
LV8772 Application Note
Evaluation board circuit
10μF
C5
0.1μF
1
VM
CP2 28
2
VG
CP1 27
3
OUT1A
4
PGND
ATT2 25
5
VM1
ATT1 24
6
RF1
EMO 23
7
OUT1B
8
OUT2A
9
RF2
C1
0.1μF
0.1μF
C3
Motor
connection
terminal
VREG5 26
(3)
0.22Ω
(4)
0.22Ω
LV8772
R3
SW1
SW2
C2
R2
R1
47KΩ
*VDD
Power supply
input terminal for
Switch
180pF
CHOP 22
C4
MONI 21
RST 20
SW3
(2)
R4
10 VM2
STEP 19
11 PGND
*VREF
Constant current
control for reference
voltage
FR 18
12 OUT2B
MD2 17
13 GND
MD1 16
14 VREF
ST 15
(1)
SW4
*CLK input
SW5
SW6
SW7
【Stepping Motor】
VM=24V, VDD=5V, VREF=1.5V
ST=H, RST=L
ATT1=ATT2=L,
FR =L, MD1 =MD2 =H
STEP =500Hz (Duty50%)
20ms/div
(1)
STEP
5V/div
(2)
MONI
5V/div
(3)
(4)
Iout1
1A/div
Iout2
1A/div
30/33
LV8772 Application Note
Evaluation Board Manual
[Supply Voltage]
VM (9 to 32V): Power Supply for LSI
VREF (0 to 3V): Const. Current Control for Reference Voltage
VDD (2 to 5V): Logic “High” voltage for toggle switch
[Toggle Switch State]
Upper Side: High (VDD)
Middle: Open, enable to external logic input
Lower Side: Low (GND)
[Operation Guide]
For stepping motor control
1. Motor Connection: Connect the Motors between OUT1A and OUT1B, between OUT2A and
OUT2B.
2. Initial Condition Setting: Set “Open” the toggle switch STEP, and “Open or Low” the other
switches.
3. Power Supply: Supply DC voltage to VM, VREF and VDD.
4. Ready for Operation from Standby State: Turn “High” the ST terminal toggle switch. Channel 1
and 2 are into 2-phase excitement initial position (100%, -100%).
5. Motor Operation: Input the clock signal into the terminal STEP.
6. Other Setting
i. ATT1, ATT2: Motor current attenuation.
ii. RST: Initial Mode.
iii. FR: Motor rotation direction (CW / CCW) setting.
iv. MD1, MD2: Excitation mode.
[Setting for External Component Value]
1. Constant Current (100%)
At VREF=1.5V
Iout
=VREF [V] / 5 / RF [Ω]
=1.5 [V] / 5 / 0.22 [Ω]
=1.36 [A]
2. Chopping Frequency
Fchop =Ichop [μA] / (Cchop x Vt x 2)
=10 [μA] / (180 [pF] x 0.5 [V] x 2)
=55 [kHz]
31/33
LV8772 Application Note
Notes in design:
●Power supply connection terminal [VM, VM1, VM2]
9 Make sure to short-circuit VM, VM1 and VM2.For controller supply voltage, the internal regulator voltage
of VREG5 (typ 5V) is used.
9 Make sure that supply voltage does not exceed the absolute MAX ratings under no circumstance.
Noncompliance can be the cause of IC destruction and degradation.
9 Caution is required for supply voltage because this IC performs switching.
9 The bypass capacitor of the power supply should be close to the IC as much as possible to stabilize
voltage. Also if you intend to use high current or back EMF is high, please augment enough capacitance.
●GND terminal [GND, PGND]
9 Since GND is the reference of the IC internal operation, make sure to connect to stable and the lowest
possible potential. Since high current flows into PGND, connect it to one-point GND.
●Internal power supply regulator terminal [VREG5]
9 VREG5 is the power supply for logic (typ 5V).
9 When VM supply is powered and ST is”H”, VREG5 operates.
9 Please connect capacitor for stabilize VREG5. The recommendation value is 0.1μF.
9 Since the voltage of VREG5 fluctuates, do not use it as reference voltage that requires accuracy.
●Input terminal
9 When you set input pin to low voltage, please short it to GND because the input pin is vulnerable to noise.
9 The input is TTL level (H: 2V or higher, L: 0.8V or lower).
9 VREF pin is high impedance.
●OUT terminal [OUT1A, OUT1B, OUT2A, OUT2B]
9 During chopping operation, the output voltage becomes equivalent to VM voltage, which can be the cause
of noise. Caution is required for the pattern layout of output pin.
9 The layout should be low impedance because driving current of motor flows into the output pin.
9 Output voltage may boost due to back EMF. Make sure that the voltage does not exceed the absolute
MAX ratings under no circumstance. Noncompliance can be the cause of IC destruction and degradation.
●Current sense resistor connection terminal [RF1, RF2]
9 To perform constant current control, please connect resistor to RF pin.
9 To perform saturation drive (without constant current control), please connect RF pin to GND.
9 If RF pin is open, then short protector circuit operates. Therefore, please connect it to resistor or GND.
9 The motor current flows into RF – GND line. Therefore, please connect it to common GND line and low
impedance line.
32/33
LV8772 Application Note
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33/33