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A3983
DMOS Microstepping Driver with Translator
Package LP
CP1 CP2 VCP VREG MS1 MS2 RESET ROSC SLEEP
1
24 GND
2 3
23 ENABLE 22 OUT2B 21 VBB2 20 SENSE2
4 5
6 7
19 OUT2A 18 OUT1A 17 SENSE1 16 VBB1 15 OUT1B 14 DIR 13 GND
8 9
VDD 10 STEP 11 REF 12
Approximate Scale 1:1
ABSOLUTE MAXIMUM RATINGS
Load Supply Voltage,VBB ...................................35 V Output Current, IOUT ......................................... 2 A* Logic Input Voltage, VIN ..................... -0.3 V to 7 V Sense Voltage, VSENSE .......................................0.5 V Reference Voltage, VREF ...................................4 V Operating Temperature Range Ambient, TA ................................. -20C to 85C Junction Temperature, TJ(MAX)..................... 150C Storage Temperature, TS .................... -55C to 150C
The A3983 is a complete microstepping motor driver with built-in translator for easy operation. It is designed to operate bipolar stepper motors in full-, half-, quarter-, and eighth-step modes, with an output drive capacity of up to 35 V and 2 A. The A3983 includes a fixed offtime current regulator which has the ability to operate in Slow or Mixed decay modes. The translator is the key to the easy implementation of the A3983. Simply inputting one pulse on the STEP input drives the motor one microstep. There are no phase sequence tables, high frequency control lines, or complex interfaces to program. The A3983 interface is an ideal fit for applications where a complex microprocessor is unavailable or is overburdened. The chopping control in the A3983 automatically selects the current decay mode (Slow or Mixed). When a signal occurs at the STEP input pin, the A3983 determines if that step results in a higher or lower current in each of the motor phases. If the change is to a higher current, then the decay mode is set to Slow decay. If the change is to a lower current, then the current decay is set to Mixed (set initially to a fast decay for a period amounting to 31.25% of the fixed off-time, then to a slow decay for the remainder of the off-time). This current decay control scheme results in reduced audible motor noise, increased step accuracy, and reduced power dissipation. Internal synchronous rectification control circuitry is provided to improve power dissipation during PWM operation. Internal circuit protection includes: thermal shutdown with hysteresis, undervoltage lockout (UVLO), and crossover-current protection. Special power-on sequencing is not required. The A3983 is supplied in a low-profile (1.2 mm maximum), 24-pin TSSOP with exposed thermal pad (package LP). It is also available in a lead (Pb) free version (suffix -T), with 100% matte tin plated leadframes.
Reg
Charge Pump
Translator & Control Logic
OSC
FEATURES
Low RDS(ON) outputs Automatic current decay mode detection/selection Mixed and Slow current decay modes Synchronous rectification for low power dissipation Internal UVLO and thermal shutdown circuitry Crossover-current protection
*Output current rating may be limited by duty cycle,
ambient temperature, and heat sinking. Under any set of conditions, do not exceed the specified current rating or a junction temperature of 150C.
Use the following complete part number when ordering:
Part Number A3983SLP A3983SLP-T Pb-free - Yes Package 24-pin, TSSOP Description Exposed thermal pad
26184.29A
A3983 DMOS Microstepping Driver with Translator
Functional Block Diagram
0.1 F 0.22 F
VREG
ROSC
CP1
CP2
VDD
Current Regulator
OSC
Charge Pump VCP
REF DMOS Full Bridge
0.1 F
VBB1
DAC
OUT1A OUT1B PWM Latch Blanking Mixed Decay
SENSE1 Gate Drive RS1 VBB2
STEP DIR RESET MS1 MS2 PWM Latch Blanking Mixed Decay Translator Control Logic
DMOS Full Bridge
OUT2A OUT2B
ENABLE SLEEP DAC
SENSE2 RS2
VREF
26184.29A
Allegro MicroSystems, Inc. 115 Northeast Cutoff, Box 15036 Worcester, Massachusetts 01615-0036 (508) 853-5000 www.allegromicro.com
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A3983 DMOS Microstepping Driver with Translator
ELECTRICAL CHARACTERISTICS1 at TA = 25C, VBB = 35 V (unless otherwise noted)
Characteristics Output Drivers Load Supply Voltage Range Logic Supply Voltage Range Output On Resistance Body Diode Forward Voltage Symbol Test Conditions Operating During Sleep Mode Operating Source Driver, IOUT = -1.5 A Sink Driver, IOUT = 1.5 A Source Diode, IF = -1.5 A Sink Diode, IF = 1.5 A fPWM < 50 kHz Operating, outputs disabled Sleep Mode fPWM < 50 kHz Outputs off Sleep Mode Min. 8 0 3.0 - - - - - - - - - - VDDx0.7 VIN = VDDx0.7 - -20 -20 - 150 0.7 20 23 0 -3 - - - 100 - - 2.35 0.05 Typ.2 - - - 0.350 0.300 - - - - - - - - - - <1.0 <1.0 100 300 1 30 30 - 0 - - - 475 165 15 2.7 0.10 Max. 35 35 5.5 0.450 0.370 1.2 1.2 4 2 10 8 5 10 - VDDx0.3 20 20 - 500 1.3 40 37 4 3 15 5 5 800 - - 3 - Units V V V V V mA mA A mA mA A V V A A k mV s s s V A % % % ns C C V V
VBB VDD RDSON VF IBB
Motor Supply Current
Logic Supply Current Control Logic Logic Input Voltage Logic Input Current Microstep Select 2 Input Hysteresis Blank Time Fixed Off-Time Reference Input Voltage Range Reference Input Current Current Trip-Level Error3 Crossover Dead Time Protection Thermal Shutdown Temperature Thermal Shutdown Hysteresis UVLO Enable Threshold UVLO Hysteresis
IDD
VIN(1) VIN(0) IIN(1) IIN(0) MS2 VHYS(IN) tBLANK tOFF VREF IREF
errI
VIN = VDDx0.3
OSC > 3 V ROSC = 25 k
VREF = 2 V, %ITripMAX = 38.27% VREF = 2 V, %ITripMAX = 70.71% VREF = 2 V, %ITripMAX = 100.00%
tDT TJ TJHYS UVLO UVHYS
VDD rising
1Negative current is defined as coming out of (sourcing from) the specified device pin. 2Typical data are for initial design estimations only, and assume optimum manufacturing and application conditions. Performance may vary for
3err
individual units, within the specified maximum and minimum limits. I = (ITrip - IProg ) IProg , where IProg = %ITripMAX ITripMAX.
x
26184.29A
Allegro MicroSystems, Inc. 115 Northeast Cutoff, Box 15036 Worcester, Massachusetts 01615-0036 (508) 853-5000 www.allegromicro.com
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A3983 DMOS Microstepping Driver with Translator
THERMAL CHARACTERISTICS may require derating at maximum conditions, see application information
Characteristic Symbol Test Conditions* One-layer PCB, one-sided with copper limited to solder pads Package Thermal Resistance RJA One layer PCB, two-sided with copper limited to solder pads and 3.8 in.2 of copper area on each side, connected to GND pins High-K PCB (multilayer with significant copper areas, based on JEDEC standard) Value Units 100 32 28 C/W C/W C/W
*In still air. Additional thermal information available on Allegro Web site.
Maximum Power Dissipation, PD(max)
5.5 5.0 4.5 4.0
H (R igh
J A
Power Dissipation, PD (W)
3.5 3.0 2.5 2.0 1.5 1.0 0.5 0.0
Lo (R w-K
J A
-K = PC 28 B C /W
=
W ) Minim um(R KP JA = 100 CB C/W )
PC 32 B C /
)
20
40
60
80 100 120 Temperature (C)
140
160
180
26184.29A
Allegro MicroSystems, Inc. 115 Northeast Cutoff, Box 15036 Worcester, Massachusetts 01615-0036 (508) 853-5000 www.allegromicro.com
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A3983 DMOS Microstepping Driver with Translator
tA
tB
STEP
tC MS1, MS2, RESET, or DIR tD
Time Duration STEP minimum, HIGH pulse width STEP minimum, LOW pulse width Setup time, input change to STEP Hold time, input change to STEP Figure 1. Logic Interface Timing Diagram
Symbol tA tB tC tD
Typ. 1 1 200 200
Unit s s ns ns
Table 1. Microstep Resolution Truth Table
MS1 L H L H MS2 L L H H Microstep Resolution Full Step Half Step Quarter Step Eighth Step Excitation Mode 2 Phase 1-2 Phase W1-2 Phase 2W1-2 Phase
26184.29A
Allegro MicroSystems, Inc. 115 Northeast Cutoff, Box 15036 Worcester, Massachusetts 01615-0036 (508) 853-5000 www.allegromicro.com
5
A3983 DMOS Microstepping Driver with Translator
Functional Description
Device Operation. The A3983 is a complete microstepping motor driver with a built-in translator for easy operation with minimal control lines. It is designed to operate bipolar stepper motors in full-, half-, quarter-, and sixteenth-step modes. The currents in each of the two output full-bridges and all of the N-channel DMOS FETs are regulated with fixed off-time PMW (pulse width modulated) control circuitry. At each step, the current for each full-bridge is set by the value of its external current-sense resistor (RS1 or RS2), a reference voltage (VREF), and the output voltage of its DAC (which in turn is controlled by the output of the translator). At power-on or reset, the translator sets the DACs and the phase current polarity to the initial Home state (shown in figures 2 through 5), and the current regulator to Mixed Decay Mode for both phases. When a step command signal occurs on the STEP input, the translator automatically sequences the DACs to the next level and current polarity. (See table 2 for the current-level sequence.) The microstep resolution is set by the combined effect of inputs MS1 and MS2, as shown in table 1. When stepping, if the new output levels of the DACs are lower than their previous output levels, then the decay mode for the active full-bridge is set to Mixed. If the new output levels of the DACs are higher than or equal to their previous levels, then the decay mode for the active full-bridge is set to Slow. This automatic current decay selection improves microstepping performance by reducing the distortion of the current waveform that results from the back EMF of the motor.
Microstep Select (MS1 and MS2). Selects the microstepping format, as shown in table 1. MS2 has a 100 k pulldown resistance. Any changes made to these inputs do not take effect until the next STEP rising edge.
Direction Input (DIR). This determines the direction of
rotation of the motor. When low, the direction will be clockwise and when high, counterclockwise. Changes to this input do not take effect until the next STEP rising edge.
Internal PWM Current Control. Each full-bridge is controlled by a fixed off-time PWM current control circuit that limits the load current to a desired value, ITRIP . Initially, a diagonal pair of source and sink DMOS outputs are enabled and current flows through the motor winding and the current sense resistor, RSx. When the voltage across RSx equals the DAC output voltage, the current sense comparator resets the PWM latch. The latch then turns off either the source DMOS FETs (when in Slow Decay Mode) or the sink and source DMOS FETs (when in Mixed Decay Mode).
The maximum value of current limiting is set by the selection of RSx and the voltage at the VREF pin. The transconductance function is approximated by the maximum value of current limiting, ITripMAX (A), which is set by ITripMAX = VREF / ( 8
x RS)
where RS is the resistance of the sense resistor () and VREF is the input voltage on the REF pin (V). The DAC output reduces the VREF output to the current sense comparator in precise steps, such that Itrip = (%ITripMAX / 100)
RESET Input (RESET). The RESET input sets the translator to a predefined Home state (shown in figures 2 through 5), and turns off all of the DMOS outputs. All STEP inputs are ignored until the RESET input is set to high. Step Input (STEP). A low-to-high transition on the STEP
input sequences the translator and advances the motor one increment. The translator controls the input to the DACs and the direction of current flow in each winding. The size of the increment is determined by the combined state of inputs MS1 and MS2.
x ITripMAX
(See table 2 for %ITripMAX at each step.) It is critical that the maximum rating (0.5 V) on the SENSE1 and SENSE2 pins is not exceeded.
Fixed Off-Time. The internal PWM current control circuitry uses a one-shot circuit to control the duration of time that the DMOS FETs remain off. The one shot off-time, tOFF, is determined by the selection of an external resistor connected from the ROSC timing pin to ground. If the ROSC
26184.29A
Allegro MicroSystems, Inc. 115 Northeast Cutoff, Box 15036 Worcester, Massachusetts 01615-0036 (508) 853-5000 www.allegromicro.com
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A3983 DMOS Microstepping Driver with Translator
pin is tied to an external voltage > 3 V, then tOFF defaults to 30 s. The ROSC pin can be safely connected to the VDD pin for this purpose. The value of tOFF (s) is approximately tOFF ROSC 825
Shutdown. In the event of a fault, overtemperature
(excess TJ) or an undervoltage (on VCP), the DMOS outputs of the A3983 are disabled until the fault condition is removed. At power-on, the UVLO (undervoltage lockout) circuit disables the DMOS outputs and resets the translator to the Home state.
Blanking. This function blanks the output of the current
sense comparators when the outputs are switched by the internal current control circuitry. The comparator outputs are blanked to prevent false overcurrent detection due to reverse recovery currents of the clamp diodes, and switching transients related to the capacitance of the load. The blank time, tBLANK (s), is approximately tBLANK 1 s
Sleep Mode (SLEEP). To minimize power consumption
when the motor is not in use, this input disables much of the internal circuitry including the output DMOS FETs, current regulator, and charge pump. A logic low on the SLEEP pin puts the A3983 into Sleep mode. A logic high allows normal operation, as well as start-up (at which time the A3983 drives the motor to the Home microstep position). When emerging from Sleep mode, in order to allow the charge pump to stabilize, provide a delay of 1 ms before issuing a Step command.
Charge Pump (CP1 and CP2). The charge pump is
used to generate a gate supply greater than that of VBB for driving the source-side DMOS gates. A 0.1 F ceramic capacitor, should be connected between CP1 and CP2. In addition, a 0.1 F ceramic capacitor is required between VCP and VBB, to act as a reservoir for operating the high-side DMOS gates.
Mixed Decay Operation. The bridge can operate in
Mixed Decay mode, depending on the step sequence, as shown in figures 3 thru 5. As the trip point is reached, the A3983 initially goes into a fast decay mode for 31.25% of the off-time. tOFF. After that, it switches to Slow Decay mode for the remainder of tOFF.
VREG (VREG). This internally-generated voltage is used
to operate the sink-side DMOS outputs. The VREG pin must be decoupled with a 0.22 F ceramic capacitor to ground. VREG is internally monitored. In the case of a fault condition, the DMOS outputs of the A3983 are disabled.
Synchronous Rectification. When a PWM-off cycle
is triggered by an internal fixed-off-time cycle, load current recirculates according to the decay mode selected by the control logic. This synchronous rectification feature turns on the appropriate FETs during current decay, and effectively shorts out the body diodes with the low DMOS RDSON. This reduces power dissipation significantly, and can eliminate the need for external Schottky diodes in many applications. Turning off synchronous rectification prevents the reversal of the load current when a zero-current level is detected.
Enable Input (ENABLE). This input turns on or off all of
the DMOS outputs. When set to a logic high, the outputs are disabled. When set to a logic low, the internal control enables the outputs as required. The translator inputs STEP, DIR, MS1, and MS2, as well as the internal sequencing logic, all remain active, independent of the ENABLE input state.
26184.29A
Allegro MicroSystems, Inc. 115 Northeast Cutoff, Box 15036 Worcester, Massachusetts 01615-0036 (508) 853-5000 www.allegromicro.com
7
A3983 DMOS Microstepping Driver with Translator
STEP
100.00 70.71
STEP
100.00 70.71
Slow
Slow Mixed
Slow Mixed
Home Microstep Position
Home Microstep Position
-70.71 -100.00 100.00 70.71
Home Microstep Position
-70.71 -100.00 100.00 70.71
Slow Slow Mixed Mixed
Slow Mixed
Slow
Phase 2 IOUT2A Direction = H (%)
0.00
Slow
-70.71
Phase 2 IOUT2B Direction = H (%)
0.00
-70.71 -100.00
-100.00
Figure 2. Decay Mode for Full-Step Increments
STEP
100.00 92.39 70.71
Figure 3. Decay Modes for Half-Step Increments
-38.27 -70.71 -92.39 -100.00 100.00 92.39 70.71
Phase 2 IOUT2B Direction = H (%)
38.27
Slow Mixed Slow Mixed Slow Mixed
0.00 -38.27 -70.71 -92.39 -100.00
Figure 4. Decay Modes for Quarter-Step Increments
Allegro MicroSystems, Inc. 115 Northeast Cutoff, Box 15036 Worcester, Massachusetts 01615-0036 (508) 853-5000 www.allegromicro.com
Home Microstep Position
Phase 1 IOUT1A Direction = H (%)
38.27
Slow
0.00
Mixed
Slow
Mixed
Slow
Home Microstep Position
Phase 1 IOUT1A Direction = H (%)
Slow
0.00
Phase 1 IOUT1A Direction = H (%)
Mixed
0.00
8
26184.29A
A3983 DMOS Microstepping Driver with Translator
STEP
100.00 92.39 83.15 70.71 55.56
-38.27 -55.56 -70.71 -83.15 -92.39 -100.00 100.00 92.39 83.15 70.71 55.56
Phase 2 IOUT2B Direction = H (%)
38.27 19.51 0.00 -19.51 -38.27 -55.56 -70.71 -83.15 -92.39 -100.00
Mixed
Slow
Home Microstep Position
Phase 1 IOUT1A Direction = H (%)
38.27 19.51 0.00 -19.51
Slow
Mixed
Slow
Mixed
Mixed
Slow
Figure 5. Decay Modes for Eighth-Step Increments
26184.29A
Allegro MicroSystems, Inc. 115 Northeast Cutoff, Box 15036 Worcester, Massachusetts 01615-0036 (508) 853-5000 www.allegromicro.com
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A3983 DMOS Microstepping Driver with Translator
Table 2. Step Sequencing Settings
Home microstep position at Step Angle 45; DIR = H
Full Step # Half Step # 1 1/4 Step # 1 2 1 2 3 4 3 5 6 2 4 7 8 5 9 10 3 6 11 12 7 13 14 4 8 15 16 1/8 Step # 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 Phase 1 Current
[% ItripMax]
Phase 2 Current
[% ItripMax]
(%) 100.00 98.08 92.39 83.15 70.71 55.56 38.27 19.51 0.00 -19.51 -38.27 -55.56 -70.71 -83.15 -92.39 -98.08 -100.00 -98.08 -92.39 -83.15 -70.71 -55.56 -38.27 -19.51 0.00 19.51 38.27 55.56 70.71 83.15 92.39 98.08
(%) 0.00 19.51 38.27 55.56 70.71 83.15 92.39 98.08 100.00 98.08 92.39 83.15 70.71 55.56 38.27 19.51 0.00 -19.51 -38.27 -55.56 -70.71 -83.15 -92.39 -98.08 -100.00 -98.08 -92.39 -83.15 -70.71 -55.56 -38.27 -19.51
Step Angle () 0.0 11.3 22.5 33.8 45.0 56.3 67.5 78.8 90.0 101.3 112.5 123.8 135.0 146.3 157.5 168.8 180.0 191.3 202.5 213.8 225.0 236.3 247.5 258.8 270.0 281.3 292.5 303.8 315.0 326.3 337.5 348.8
26184.29A
Allegro MicroSystems, Inc. 115 Northeast Cutoff, Box 15036 Worcester, Massachusetts 01615-0036 (508) 853-5000 www.allegromicro.com
10
A3983 DMOS Microstepping Driver with Translator
Pin List Table Name CP1 CP2 VCP VREG MS1 MS2 RESET ROSC SLEEP VDD STEP REF GND DIR OUT1B VBB1 SENSE1 OUT1A OUT2A SENSE2 VBB2 OUT2B ENABLE GND Description Charge pump capacitor 1 Charge pump capacitor 2 Reservoir capacitor Regulator decoupling Logic input Logic input Logic input Timing set Logic input Logic supply Logic input
Current trip reference voltage input
Number 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24
Ground* Logic input DMOS Full Bridge 1 Output B Load supply Sense resistor for Bridge 1 DMOS Full Bridge 1 Output A DMOS Full Bridge 2 Output A Sense resistor for Bridge 2 Load supply DMOS Full Bridge 2 Output B Logic input Ground*
*The two GND pins must be tied together externally by connecting to the exposed pad ground plane under the device.
26184.29A
Allegro MicroSystems, Inc. 115 Northeast Cutoff, Box 15036 Worcester, Massachusetts 01615-0036 (508) 853-5000 www.allegromicro.com
11
A3983 DMOS Microstepping Driver with Translator
LP Package, 24-Pin TSSOP with Exposed Thermal Pad
26184.29A
Allegro MicroSystems, Inc. 115 Northeast Cutoff, Box 15036 Worcester, Massachusetts 01615-0036 (508) 853-5000 www.allegromicro.com
12
A3983 DMOS Microstepping Driver with Translator
The products described here are manufactured under one or more U.S. patents or U.S. patents pending. Allegro MicroSystems, Inc. reserves the right to make, from time to time, such departures from the detail specifications as may be required to permit improvements in the performance, reliability, or manufacturability of its products. Before placing an order, the user is cautioned to verify that the information being relied upon is current. Allegro products are not authorized for use as critical components in life-support devices or systems without express written approval. The information included herein is believed to be accurate and reliable. However, Allegro MicroSystems, Inc. assumes no responsibility for its use; nor for any infringement of patents or other rights of third parties which may result from its use.
Copyright(c)2005 AllegroMicrosystems, Inc.
Allegro MicroSystems, Inc. 115 Northeast Cutoff, Box 15036 Worcester, Massachusetts 01615-0036 (508) 853-5000 www.allegromicro.com
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26184.29A

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