LV8734V [ONSEMI]
PWM Constant-Current Control Stepper Motor Driver;
| 型号： | LV8734V |
| 厂家： | 
ONSEMI |
| 描述： | PWM Constant-Current Control Stepper Motor Driver 信息通信管理 光电二极管 |
| 文件： | 总26页 (文件大小：310K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
Ordering number : ENA1824B
LV8734V
Monolithic Linear IC
http://onsemi.com
PWM Constant-Current Control
Stepper Motor Driver
Overview
The LV8734V is a 2-channel H-bridge driver IC that can switch a stepper motor driver, which supports micro-step
drive with 1/8-step resolution, and two channels of a brushed motor driver, which supports forward, reverse, brake, and
standby of a motor. It is ideally suited for driving brushed DC motors and stepper motors used in office equipment and
amusement applications.
Function
• Single-channel PWM current control stepper motor driver (selectable with DC motor driver channel 2) incorporated.
• BiCDMOS process IC
• Low on resistance (upper side : 0.48Ω ; lower side : 0.32Ω ; total of upper and lower : 0.8Ω ; Ta = 25°C, I = 1.5A)
O
• Micro-step mode can be set to Full-step, Half-step, Quarter-step , or 1/8-step
• Excitation step proceeds only by step signal input
• Motor current selectable in four steps
• Output short-circuit protection circuit (selectable from latch-type or auto-reset-type) incorporated
• Unusual condition warning output pins
• Built-in thermal shutdown circuit
• No control power supply required
Specifications
Absolute Maximum Ratings at Ta = 25°C
Parameter
Symbol
Conditions
Ratings
Unit
V
Supply voltage
VM max
VM, VM1, VM2
36
1.75
Output peak current
Output current
I
I
peak
tw ≤ 10ms, duty 20%, per 1ch
A
O
O
max
max
Per 1ch
1.5
A
ATT1, ATT2, EMM, RST/BLK, STEP/DC22,
FR/DC21, MD2/DC12, MD1/DC11, DM,
OE/CMK, ST
Logic input voltage
V
-0.3 to +6
V
IN
MONI/EMO input voltage
Allowable power dissipation
Operating temperature
Storage temperature
Vmo/Vemo
Pd max
Topr
-0.3 to +6
3.25
V
*
W
°C
°C
-40 to +85
-55 to +150
Tstg
* Specified circuit board : 90.0mm×90.0mm×1.6mm, glass epoxy 2-layer board, with backside mounting.
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.
ORDERING INFORMATION
See detailed ordering and shipping information on page 26 of this data sheet.
Semiconductor Components Industries, LLC, 2013
June, 2013
61913NK 20130402-S00002 No.A1824-1/26
LV8734V
Allowable Operating Ratings at Ta = 25°C
Parameter
Supply voltage range
Logic input voltage
Symbol
Conditions
Ratings
Unit
V
VM
VM, VM1, VM2
9 to 32
0 to 5.5
ATT1, ATT2, EMM, RST/BLK, STEP/DC22, FR/DC21,
MD2/DC12, MD1/DC11, DM, OE/CMK, ST
V
V
IN
VREF input voltage range
VREF
0 to 3
V
Electrical Characteristics at Ta = 25°C, VM = 24V, VREF = 1.5V
Ratings
typ
100
Parameter
Symbol
Conditions
Unit
min
max
400
5
Standby mode current drain
Current drain
IMst
ST = “L” , I(VM)+I(VM1)+I(VM2)
μA
IM
ST = “H”, OE = “L”, with no load
I(VM)+I(VM1)+I(VM2)
3.2
mA
VREG5 output voltage
Thermal shutdown temperature
Thermal hysteresis width
Motor driver
Vreg5
TSD
I
= -1mA
4.5
5
180
40
5.5
V
O
Design guarantee
Design guarantee
150
200
°C
°C
ΔTSD
Output on resistance
Ronu
Rond
I
I
= 1.5A, Upper-side on resistance
= 1.5A, Lower-side on resistance
0.48
0.32
0.63
0.42
50
Ω
Ω
O
O
Output leakage current
Diode forward voltage
I
leak
μA
V
O
VD
V
ID = -1.5A
1.2
8
1.4
5.5
0.8
12
ATT1, ATT2, EMM, RST/BLK, STEP/DC22,
FR/DC21, MD2/DC12, MD1/DC11, DM,
OE/CMK, ST
Logic input voltage
High
Low
H
L
2.0
0
V
IN
V
V
IN
Logic pin input current
I
L
ATT1, ATT2, EMM, RST/BLK, STEP/DC22,
FR/DC21, MD2/DC12, MD1/DC11, DM, ST,
4
μA
IN
Except the OE/CMK pin
V
V
= 0.8V
= 5V
IN
IN
I
I
I
I
H
30
4
50
8
70
12
μA
μA
μA
μA
V
IN
OE / CMK pin input current
L
DM = “L”, OE/CMK = 0.8V
DM = “L”, OE/CMK = 5V
DM = “H”, OE/CMK = 0V
DM = “H”
CMK
CMK
CMK
H
30
-32
1.2
50
-25
1.5
70
-18
1.8
OE/CMK pin current LIMIT mask
threshold voltage.
Vt
CMK
Current setting
comparator
threshold
1/8 step
Vtdac0_2W
Step 0 (When initialized : channel 1
comparator level)
0.291
0.3
0.309
V
resolution
Vtdac1_2W
Vtdac2_2W
Vtdac3_2W
Vtdac4_2W
Vtdac5_2W
Vtdac6_2W
Vtdac7_2W
Vtdac0_W
Step 1 (Initial state+1)
0.285
0.267
0.240
0.201
0.157
0.107
0.053
0.291
0.294
0.276
0.249
0.21
0.303
0.285
0.258
0.219
0.173
0.121
0.067
0.309
V
V
V
V
V
V
V
V
voltage
Step 2 (Initial state+2)
Step 3 (Initial state+3)
Step 4 (Initial state+4)
Step 5 (Initial state+5)
Step 6 (Initial state+6)
Step 7 (Initial state+7)
(current step
switching)
0.165
0.114
0.06
Quarter step
resolution
Step 0 (When initialized : channel 1
comparator level)
0.3
Vtdac2_W
Vtdac4_W
Vtdac6_W
Vtdac0_H
Step 2 (Initial state+1)
0.267
0.201
0.107
0.291
0.276
0.21
0.114
0.3
0.285
0.219
0.121
0.309
V
V
V
V
Step 4 (Initial state+2)
Step 6 (Initial state+3)
Half step
resolution
Step 0 (When initialized : channel 1
comparator level)
Vtdac4_H
Vtdac4_F
Step 4 (Initial state+1)
0.201
0.291
0.21
0.3
0.219
0.309
V
V
Full step
Step 4' (When initialized : channel 1
comparator level)
resolution
Current setting comparator
threshold voltage
Vtatt00
Vtatt01
Vtatt10
Vtatt11
ATT1 = L, ATT2 = L
0.291
0.232
0.143
0.053
0.3
0.24
0.15
0.06
0.309
0.248
0.157
0.067
V
V
V
V
ATT1 = H, ATT2 = L
ATT1 = L, ATT2 = H
ATT1 = H, ATT2 = H
(current attenuation rate switching)
Continued on next page.
No.A1824-2/26
LV8734V
Continued from preceding page.
Ratings
typ
Parameter
Symbol
Fchop
Conditions
Unit
min
max
Chopping frequency
Cchop = 200pF
40
7
50
60
13
kHz
CHOP pin charge/discharge current
Ichop
10
1
μA
Chopping oscillation circuit
threshold voltage
Vtup
0.8
0.4
1.2
0.6
V
V
Vtdown
Iref
0.5
VREF pin input current
MONI pin saturation voltage
Charge pump
VREF = 1.5V
Imoni = 1mA
-0.5
μA
Vsatmon
400
mV
VG output voltage
Rise time
VG
28
90
28.7
200
29.8
500
V
tONG
VG = 0.1μF, 0.1μF between CP1-CP2
ST= “H” → VG=VM+4V
μS
Oscillator frequency
Fosc
125
150
kHz
Output short-circuit protection
EMO pin saturation voltage
CEM pin charge current
CEM pin threshold voltage
Vsatemo
Icem
Iemo = 1mA
400
13
mV
μA
V
7
10
1
Vtcem
0.8
1.2
Package Dimensions
unit : mm (typ)
3333A
TOP VIEW
SIDE VIEW
BOTTOM VIEW
15.0
44
23
(4.7)
1
22
0.65
0.22
0.2
(0.68)
SIDE VIEW
SSOP44K(275mil)
No.A1824-3/26
LV8734V
Pd max - Ta
4.0
Four-layer circuit board 1 * 1
3.25
3.0
Four-layer circuit board 2 * 2
2.20
2.0
1.69
1.14
1.0
0
*1 With components mounted on the exposed die-pad board
*2 With no components mounted on the exposed die-pad board
0
20
40
60
80
100
Substrate Specifications (Substrate recommended for operation of LV8734V)
Size
Material
: 90mm × 90mm × 1.6mm (two-layer substrate [2S0P])
: Glass epoxy
Copper wiring density : L1 = 85% / L2 = 90%
L1 : Copper wiring pattern diagram
L2 : Copper wiring pattern diagram
Cautions
1) The data for the case with the Exposed Die-Pad substrate mounted shows the values when 90% or more of the
Exposed Die-Pad is wet.
2) For the set design, employ the derating design with sufficient margin.
Stresses to be derated include the voltage, current, junction temperature, power loss, and mechanical stresses such as
vibration, impact, and tension.
Accordingly, the design must ensure these stresses to be as low or small as possible.
The guideline for ordinary derating is shown below :
(1)Maximum value 80% or less for the voltage rating
(2)Maximum value 80% or less for the current rating
(3)Maximum value 80% or less for the temperature rating
3) After the set design, be sure to verify the design with the actual product.
Confirm the solder joint state and verify also the reliability of solder joint for the Exposed Die-Pad, etc.
Any void or deterioration, if observed in the solder joint of these parts, causes deteriorated thermal conduction,
possibly resulting in thermal destruction of IC.
No.A1824-4/26
LV8734V
Pin Assignment
VG
VM
1
2
3
4
5
6
7
8
9
44 OUT1A
43 OUT1A
42 PGND
41 NC
CP2
CP1
VREG5
ATT2
ATT1
EMO
CEM
40 NC
39 VM1
38 VM1
37 RF1
36 RF1
EMM 10
CHOP 11
35 OUT1B
34 OUT1B
33 OUT2A
32 OUT2A
31 RF2
LV8734V
MONI 12
RST/BLK 13
STEP/DC22 14
FR/DC21 15
MD2/DC12 16
MD1/DC11 17
DM 18
30 RF2
29 VM2
28 VM2
27 NC
OE/CMK 19
ST 20
26 NC
25 PGND
24 OUT2B
23 OUT2B
VREF 21
GND 22
Top view
No.A1824-5/26
LV8734V
Block Diagram
O u t p u t p r e a m p l i f i e r s t a g e
O u t p u t p r e a m p l i f i e r s t a g e
O u t p u t p r e a m p l i f i e r s t a g e
O u t p u t p r e a m p l i f i e r s t a g e
No.A1824-6/26
LV8734V
Pin Functions
Pin No.
Pin Name
Pin Function
Equivalent Circuit
6
7
ATT2
ATT1
EMM
Motor holding current switching pin.
Motor holding current switching pin.
Output short-circuit protection mode
switching pin.
10
VREG5
13
14
15
RST/BLK
RESET input pin (STM) / Blanking time
switching pin (DCM).
STEP/DC22
FR/DC21
STEP signal input pin (STM) / Channel 2
output control input pin 2 (DCM).
CW / CCW signal input pin (STM) /
Channel 2 output control input pin 1
(DCM).
10kΩ
16
17
MD2/DC12
MD1/DC11
Excitation mode switching pin 2 (STM) /
Channel 1 output control input pin 2
(DCM).
100kΩ
Excitation mode switching pin 1 (STM) /
Channel 1 output control input pin 1
(DCM).
GND
18
20
DM
ST
Drive mode (STM/DCM) switching pin.
Chip enable pin.
VREG5
20kΩ
10kΩ
80kΩ
GND
23, 24 OUT2B
25, 42 PGND
28, 29 VM2
Channel 2 OUTB output pin.
Power system ground.
38 39
28 29
Channel 2 motor power supply
connection pin.
30, 31 RF2
Channel 2 current-sense resistor
connection pin.
32, 33 OUT2A
34, 35 OUT1B
36, 37 RF1
Channel 2 OUTA output pin.
Channel 1 OUTB output pin.
Channel 1 current-sense resistor
connection pin.
43 44
32 33
34 35
23 24
38, 39 VM1
Channel 1 motor power supply pin.
Channel 1 OUTA output pin.
43, 44 OUT1A
10kΩ
25 42
500Ω
500Ω
36 37
30 31
GND
Continued on next page.
No.A1824-7/26
LV8734V
Continued from preceding page.
Pin No.
Pin Name
VG
Pin Function
Equivalent Circuit
2
1
2
3
4
Charge pump capacitor connection pin.
Motor power supply connection pin.
Charge pump capacitor connection pin.
Charge pump capacitor connection pin.
4
3
1
VM
VREG5
CP2
CP1
100Ω
GND
21
VREF
Constant current control reference
voltage input pin.
VREG5
500Ω
GND
VM
5
VREG5
Internal power supply capacitor
connection pin.
2kΩ
78kΩ
26kΩ
GND
8
EMO
Output short-circuit state warning output
pin.
VREG5
12
MONI
Position detection monitor pin.
GND
Continued on next page.
No.A1824-8/26
LV8734V
Continued from preceding page.
Pin No.
9
Pin Name
CEM
Pin Function
Equivalent Circuit
Pin to connect the output short-circuit
state detection time setting capacitor.
VREG5
GND
11
CHOP
Chopping frequency setting capacitor
connection pin.
VREG5
500Ω
500Ω
GND
19
OE/CMK
Output enable signal input pin(STM) /
Set capacitor connection pin of time of
current LIMIT mask(DCM).
VREG5
GND
22
GND
Ground.
26, 27 NC
40, 41
No Connection
(No internal connection to the IC)
No.A1824-9/26
LV8734V
Description of operation
1.Input Pin Function
Each input terminal has the function to prevent the flow of the current from an input to a power supply.
Therefore, even if a power supply (VM) is turned off in the state that applied voltage to an input terminal,
the electric current does not flow into the power supply.
1-1) Chip enable 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
Low or Open
High
Mode
Internal regulator
Charge pump
Standby mode
Operating mode
Standby
Standby
Operating
Operating
1-2) Drive mode switching pin function
The IC drive mode is switched by setting the DM pin. In STM mode, stepper motor channel 1 can be controlled by the
CLK-IN input. In DCM mode, DC motor channel 2 or stepper motor channel 1 can be controlled by parallel input.
Stepper motor control using parallel input is Full-step or Half-step full torque.
DM
Low or Open
High
Drive mode
STM mode
DCM mode
Application
Stepper motor channel 1 (CLK-IN)
DC motor channel 2 or stepper motor channel 1 (parallel)
2.STM mode (DM = Low or Open)
2-1) STEP pin function
Input
Operating mode
Standby mode
ST
STP
*
Low
High
Excitation step proceeds
High
Excitation step is kept
2-2) Excitation mode setting function
MD1
MD2
Micro-step resolution
(Excitation mode)
Initial position
Channel 1
100%
Channel 2
-100%
0%
Low
High
Low
Low
Low
High
Full step(2 phase excitation)
Half step(-2 phase excitation)
100%
Quarter step
100%
0%
(W1-2 phase excitation)
1/8 step(2W1-2 phase excitation)
High
High
100%
0%
This is the initial position of each excitation mode in the initial state after power-on and when the counter is reset.
2-3) 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 "2-12.Examples of current waveforms in each micro-step mode.")
No.A1824-10/26
LV8734V
2-4) 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 :
I
= (VREF/5)/RF resistance
OUT
* 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%
80%
50%
20%
High
Low
Low
High
High
High
The formula used to calculate the output current when using the function for attenuating the VREF input voltage is
given below.
I
= (VREF/5) × (attenuation ratio)/RF resistance
OUT
Example : At VREF of 1.5V, 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.
I
= 1.5V/5 × 100%/0.5Ω = 0.6A
OUT
If, in this state, (ATT1, ATT2) is set to (H, H), IOUT will be as follows :
= 0.6A × 20% = 120mA
I
OUT
In this way, the output current is attenuated when the motor holding current is supplied so that power can
be conserved.
2-5) Input timing
TstepL
TstepH
STEP
MD1
MD2
Tds
Tdh
(md1 step) (step md1)
Tds
Tdh
(md2 step) (step md2)
Tdh
(step fr)
Tds
(fr step)
FR
TstepH/TstepL : Clock H/L pulse width (min 500ns)
Tds : Data set-up time (min 500ns)
Tdh : Data hold time (min 500ns)
2-6) Blanking time
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 time is provided to prevent the noise occurring during mode switching from being received.
During this time, the mode is not switched from charge to decay even if noise is carried on the current sensing
resistance pin.
In the stepper motor driver mode (DM = Low or Open) of this IC, the blanking time is fixed at approximately 1μs.
In the DC motor driver mode (DM = High), the blanking time can be switched to one of two levels using the
RST/BLK pin. (Refer to "Blanking time switching function.")
No.A1824-11/26
LV8734V
2-7) Reset function
(Only the STM mode. : It change the BLK terminal at DCM mode. It operates as a switch function of the blanking time.
Refer to (Blanking time switching function))
RST
Low
High
Operating mode
Normal operation
Reset state
RST
RESET
STEP
MONI
1ch output
0%
2ch output
Initial state
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.
2-8) Output enable function
(Only the STM mode. : It change the CMK terminal at DCM mode. It operates as current LIMIT mask function. Refer to (Current
limit reference voltage setting function))
OE
Low
High
Operating mode
Output ON
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.A1824-12/26
LV8734V
2-9) Forward/reverse switching function
FR
Operating mode
Low
High
Clockwise (CW)
Counter-clockwise (CCW)
CW mode
FR
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.
2-10) 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.
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/ (200pF × 0.5V × 2) = 50kHz
No.A1824-13/26
LV8734V
2-11) Output current vector locus (one step is normalized to 90 degrees)
100.0
θ4' (2-phase)
θ 0
θ 1
θ 2
θ 3
θ 4
66.7
θ 5
θ 6
33.3
θ 7
θ 8
0.0
0.0
33.3
66.7
100.0
Channel 2 current ratio (%)
Setting current ration in each micro-step mode
STEP
1/8 step (%)
Quarter step (%)
Half step (%)
Channel 1 Channel 2
100
Full step (%)
Channel 1 Channel 2
Channel 1 Channel 2
Channel 1 Channel 2
θ0
θ1
θ2
θ3
θ4
θ5
θ6
θ7
θ8
100
98
92
83
70
55
38
20
0
0
20
100
92
70
38
0
0
38
0
38
55
70
70
70
70
100
100
83
92
92
98
100
100
0
100
No.A1824-14/26
LV8734V
2-12) Examples of current waveform in each micro-step mode
Full step (CW mode)
STEP
MONI
(%)
100
l1
I2
0
-100
(%)
100
0
-100
Half step (CW mode)
STEP
MONI
(%)
100
I1
I2
0
-100
(%)
100
0
-100
No.A1824-15/26
LV8734V
Quarter step (CW mode)
STEP
MONI
(%)
100
I1
0
-100
(%)
100
I2
0
-100
1/8 step (CW mode)
STEP
MONI
(%)
100
50
0
I1
-50
-100
(%)
100
50
0
I2
-50
-100
No.A1824-16/26
LV8734V
2-13) 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
Set current
Current mode CHARGE
SLOW
FAST
Forced CHARGE FAST
section
CHARGE
SLOW
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 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.A1824-17/26
LV8734V
3.DCM Mode (DM=High)
3-1) DCM mode output control logic
Parallel input
Output
Mode
DC11 (21)
Low
DC12 (22)
Low
OUT1 (2) A
OFF
OUT1 (2) B
OFF
Standby
CW (Forward)
CCW (Reverse)
Brake
High
Low
High
Low
Low
High
Low
High
High
High
Low
Low
3-2) Blanking time switching function
(Only the DCM mode. : It change the RST terminal at STM mode. It operates as RESET function. Refer to (reset function))
BLK
Low
High
Blanking time
2μs
3μs
3-3) Current limit reference voltage setting function
By setting a current limit, this IC automatically exercises short braking control to ensure that when the motor current
has reached this limit, the current will not exceed it.
(Current limit control time chart)
Set current
Current mode
Coil current
Forced CHARGE
section
fchop
Current mode CHARGE
SLOW
The limit current is set as calculated on the basis of the voltage input to the VREF pin and the resistance between the
RF pin and GND using the formula given below.
Ilimit = (VREF/5) /RF resistance
The voltage applied to the VREF pin can be switched to any of the four setting levels depending on the statuses of the
two inputs, ATT1 and ATT2.
Function for attenuating VREF input voltage
ATT1
ATT2
Current setting reference voltage attenuation ratio
Low
Low
100%
80%
50%
20%
High
Low
Low
High
High
High
The formula used to calculate the output current when using the function for attenuating the VREF input voltage is
given below.
Ilimit = (VREF/5) × (attenuation ratio) /RF resistance
Example : At VREF of 1.5V, 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.
Ilimit = 1.5V/5 × 100%/0.5Ω = 0.6A
If, in this state, (ATT1, ATT2) has been set to (H, H), Ilimit will be as follows :
Ilimit = 0.6A × 20% = 120mA
No.A1824-18/26
LV8734V
3-4) Current LIMIT mask function
(Only the DCM mode. : It change the OE terminal at STM mode. It operates as output enable function. Refer to (output enable
function))
The mask can do current LIMIT function during the fixed time set with the CMK pin at the DCM mode. It is effective
to make it not hang to the limiter by the start current of the motor to set current LIMIT low.
The charge is begun, current LIMIT function is done to the CMK capacitor meanwhile when switching to forward/
reverse mode, and the mask is done. Afterwards, the mask is released when the voltage of the CMK pin reaches set
voltage (typ 1.5V), and the current limit function works.
When 2ch side begins forward (reverse) operation while the mask on 1ch side is operating, the CMK pin is discharged
one degree up to a constant voltage, and begins charging again because the CMK pin becomes 2ch using combinedly.
Meanwhile, 1ch side and 2ch side enter the state of the mask.
forward
forward
1ch operate
2ch operate
brake
brake
brake
forward
forward
brake
brake
brake
1.5V
CMK
(capacitor)
0.3V
1ch
release
release
release
mask
mask
mask
mask
current limit
2ch
current limit
release
mask
mask
When the capacitor is not connected, the function of LIMIT in the current can be switched to operation/no operating
state by the state of the input of the CMK pin.
CMK
“L”
Current LIMIT function
no operating
“H” or OPEN
operation
3-5) Current LIMIT mask time (Tcmk)
The time of the mask of current LIMIT function can be set by connecting capacitor C
between CMK pin - GND.
CMK
Decide the value of capacitor C
CMK
according to the following expressions.
Mask time : T
T
≈ -C
CMK
× R × 1n ( 1- Vt
: LIMIT mask threshold voltage typ. 1.5V
/ (I
× R )) (sec)
CMK CMK
Vt
CMK CMK
CMK
: CMK pin charge current typ. 25μA
I
CMK
R : Internal resistance typ. 100kΩ
No.A1824-19/26
LV8734V
3-6) Examples of current waveform in each micro-step mode when stepper motor parallel input control
Full step (CW mode)
DC11
DC12
DC21
DC22
(%)
100
I1
I2
0
-100
(%)
100
0
-100
Half step full torque (CW mode)
DC11
DC12
DC21
DC22
(%)
100
l1
l2
0
-100
(%)
100
0
-100
No.A1824-20/26
LV8734V
4.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. In the stepping motor driver (STM) mode (DM = Low), this function
sets the output to the standby mode for both channels by detecting the short-circuiting in one of the channels. In the
DC motor driver mode (DM = High), channels 1 and 2 operate independently. (Even if the output of channel 1 has
been short-circuited, channel 2 will operate normally.)
4-1) Output short-circuit protection mode switching function
Output short-circuit protection mode of IC can be switched by the setting of EMM pin.
EMM
Low or Open
High
State
Latch method
Auto reset method
4-2) Latch type
In the latch mode, when the output current exceeds the detection current level, the output is turned OFF, and this state
is held.
The detection of the output short-circuited state by the IC causes the output short-circuit protection circuit to be
activated.
When the short-circuited state continues for the time of time set using the internal timer (approximately 2μs), the
output in which the short-circuiting has been detected is first set to OFF. After this, the output is set to ON again as
soon as the timer latch time (Tcem) described later has been exceeded, and if the short-circuited state is still detected,
all the outputs of the channel concerned are switched to the standby mode, and this state is held.
This state is released by setting ST to low.
Output ON
Output ON
Output OFF
Standby state
H-bridge
output state
Threshold voltage
CEM voltage
Short-circuit
detection state
Short- Release
circuit
Short-circuit
Internal counter
1st counter 1st counter 1st counter
start stop start
1st counter
end
2nd counter 2nd counter
start end
No.A1824-21/26
LV8734V
4-3) Auto reset type
In the automatic reset mode, when the output current exceeds the detection current level, the output waveform
changes to the switching waveform.
As with the latch system, when the output short-circuited state is detected, the short-circuit protection circuit is
activated. When the operation of the short-circuit detection circuit exceeds the timer latch time (Tcem) described later,
the output is changed over to the standby mode and is reset to the ON mode again in 2ms (typ). In this event, if the
overcurrent mode still continues, the switching mode described above is repeated until the overcurrent mode is
canceled.
4-4) Unusual condition warning output pins (EMO, MONI)
The LV8731V 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.
In the DC motor driver mode (DM = High), the MONI pin also functions as a warning output pin.
The functions of the EMO pin and MONI pin change as shown below depending on the state of the DM pin.
When the DM is low (STM mode) :
EMO : Unusual condition warning output pin
MONI : Excitation initial position detection monitoring
When the DM is high (DCM) mode) :
EMO : Channel 1 warning output pin
MONI : Channel 2 warning output pin
Furthermore, the EMO (MONI) 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.
Unusual condition
DM = L (STM mode)
DM = H (DCM mode)
EMO
ON
MONI
EMO
ON
-
MONI
-
Channel 1 short-circuit detected
Channel 2 short-circuit detected
Overheating condition detected
-
-
-
ON
ON
ON
ON
ON
4-5) Timer latch time (Tcem)
The time taken for the output to be set to OFF when the output has been short-circuited can be set using capacitor
Ccem, connected between the CEM pin and GND. The value of capacitor Ccem is determined by the formula given
below.
Timer latch : Tcem
Tcem ≈ Ccem × Vtcem/Icem [sec]
Vtcem : Comparator threshold voltage, typ 1V
Icem : CEM pin charge current, typ 10μA
5. Thermal shutdown function
The thermal shutdown circuit is included, and the output is turned off when junction temperature Tj
exceeds 180°C and the abnormal state warning output is turned on at the same time.
When the temperature falls hysteresis level, output is driven again (automatic restoration)
The thermal shutdown circuit doesn’t guarantee protection of the set and the destruction prevention
of IC, because it works at the temperature that is higher than rating (Tjmax=150°C) of the junction
temperature
TSD = 180°C (typ)
ΔTSD = 40°C (typ)
No.A1824-22/26
LV8734V
6.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.
If the VG pin voltage is not boosted to VM+4V or more, the output pin cannot be turned on. Therefore it is
recommended that the drive of motor is started after the time has passed tONG or more.
ST
VG pin voltage
VM+VREG5
VM+4V
VM
tONG
VG Pin Voltage Schematic View
No.A1824-23/26
LV8734V
7.Application Circuit Example
7-1) Stepper motor driver circuit (DM = Low)
1
2
VG
OUT1A 44
OUT1A 43
PGND 42
VM
CP2
3
4
41
40
39
38
37
36
35
34
33
32
31
30
29
28
27
26
25
24
23
CP1
NC
NC
5
VREG5
ATT2
24V
+ -
6
VM1
7
ATT1
VM1
Short-circuit state
detection monitor
8
EMO
RF1
9
CEM
RF1
100pF
10
11
12
13
14
15
16
17
18
19
20
21
22
EMM
OUT1B
OUT1B
OUT2A
OUT2A
RF2
CHOP
MONI
180pF
Position detection
monitor
M
RST/BLK
STEP/DC22
FR/DC21
MD2/DC12
MD1/DC11
DM
Clock input
RF2
VM2
VM2
Logic input
NC
OE/CMK
ST
NC
PGND
OUT2B
OUT2B
- +
VREF
1.0V
GND
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
I
= VREF/5/RF resistance
OUT
= 1.0V/5/0.22Ω = 0.91A
Chopping frequency setting
Fchop = Ichop/ (Cchop × Vtchop × 2)
= 10μA/ (180pF × 0.5V × 2) = 55kHz
Timer latch time when the output is short-circuited
Tcem = Ccem × Vtcem/Icem
= 100pF × 1V/10μA = 10μs
No.A1824-24/26
LV8734V
7-2) DC motor driver circuit (DM = High, and the current limit function is in use.)
1
2
VG
OUT1A 44
OUT1A 43
PGND 42
VM
CP2
3
4
41
40
39
38
37
36
35
34
33
32
31
30
29
28
27
26
25
24
23
CP1
NC
NC
5
VREG5
ATT2
24V
+ -
6
M
VM1
7
ATT1
VM1
Channel 1 short-circuit
state detection monitor
8
EMO
RF1
9
CEM
RF1
100pF
10
11
12
13
14
15
16
17
18
19
20
21
22
EMM
OUT1B
OUT1B
OUT2A
OUT2A
RF2
CHOP
MONI
180pF
Channel 2 position
detection monitor
RST/BLK
STEP/DC22
FR/DC21
MD2/DC12
MD1/DC11
DM
RF2
VM2
M
Logic input
VM2
NC
OE/CMK
ST
NC
PGND
OUT2B
OUT2B
- +
VREF
1.0V
GND
The formulae for setting the constants in the examples of the application circuits above are as follows :
Constant current limit (100%) setting
When VREF = 1.0V
Ilimit = VREF/5/RF resistance
= 1.0V/5/0.22Ω = 0.91A
Chopping frequency setting
Fchop = Ichop/ (Cchop × Vtchop × 2)
= 10μA/ (180pF × 0.5V × 2) = 55kHz
Timer latch time when the output is short-circuited
Tcem = Ccem × Vtcem/Icem
= 100pF × 1V/10μA = 10μs
No.A1824-25/26
LV8734V
ORDERING INFORMATION
Device
Package
Shipping (Qty / Packing)
30 / Fan-Fold
SSOP44K (275mil)
(Pb-Free / Halogen Free)
LV8734V-MPB-H
SSOP44K (275mil)
(Pb-Free / Halogen Free)
LV8734V-TLM-H
2000 / Tape & Reel
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PS No.A1824-26/26
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