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3967 Schematic ( PDF Datasheet ) - Allegro MicroSystems

Teilenummer 3967
Beschreibung MICROSTEPPING DRIVER WITH TRANSLATOR
Hersteller Allegro MicroSystems
Logo Allegro MicroSystems Logo 




Gesamt 16 Seiten
3967 Datasheet, Funktion
3967
MICROSTEPPING DRIVER WITH TRANSLATOR
REF 1
RC2 2
÷8
PWM
TIMER
24 PFD
23 RC1
SLEEP 3
22 RESET
OUT2B 4
LOAD
SUPPLY2
5 VBB2
GND 6
21 OUT1B
LOAD
VBB1 20 SUPPLY1
19 GND
GND 7
18 GND
SENSE2 8
17 SENSE1
OUT2A 9
16 OUT1A
STEP 10
DIR 11
MS1 12
TRANSLATOR
15 ENABLE
& CONTROL
LOGIC
VCC
14
LOGIC
SUPPLY
13 MS2
Dwg. PP-075-2
ABSOLUTE MAXIMUM RATINGS
at TA = +25°C
Load Supply Voltage, VBB ............. 30 V
Output Current, IOUT
Continuous ..................... ±750 mA*
Peak ................................. ±850 mA
Logic Supply Voltage, VCC ........... 7.0 V
Logic Input Voltage Range, VIN
(tw >30 ns) ............. -0.3 V to +7.0 V
(tw <30 ns) ................ -1 V to +7.0 V
Sense Voltage, VSENSE ............... 0.68 V
Reference Voltage, VREF ................ VCC
Package Power Dissipation,
PD ................................. See page 8
Operating Temperature Range,
TA ........................... -20°C to +85°C
Junction Temperature, TJ ......... +150°C
Storage Temperature Range,
TS ......................... -55°C to +150°C
* 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 150°C.
The A3967SLB is a complete microstepping motor driver with
built-in translator. It is designed to operate bipolar stepper motors in
full-, half-, quarter-, and eighth-step modes, with output drive capabil-
ity of 30 V and ±750 mA. The A3967SLB includes a fixed off-time
current regulator that has the ability to operate in slow, fast, or mixed
current-decay modes. This current-decay control scheme results in
reduced audible motor noise, increased step accuracy, and reduced
power dissipation.
The translator is the key to the easy implementation of the
A3967SLB. By simply inputting one pulse on the STEP input the
motor will take one step (full, half, quarter, or eighth depending on two
logic inputs). There are no phase-sequence tables, high-frequency
control lines, or complex interfaces to program. The A3967SLB
interface is an ideal fit for applications where a complex µP is unavail-
able or over-burdened.
Internal circuit protection includes thermal shutdown with hyster-
esis, under-voltage lockout (UVLO) and crossover-current protection.
Special power-up sequencing is not required.
The A3967SLB is supplied in a 24-pin SOIC with four internally
fused pins for enhanced thermal dissipation. The pins are at ground
potential and need no insulation. A lead (Pb) free (100% matte tin
leadframe) version is also available.
FEATURES
±750 mA, 30 V Output Rating
Satlington® Sink Drivers
Automatic Current-Decay Mode Detection/Selection
3.0 V to 5.5 V Logic Supply Voltage Range
Mixed, Fast, and Slow Current-Decay Modes
Internal UVLO and Thermal Shutdown Circuitry
Crossover-Current Protection
Part Number Pb-free* Package
Packing
A3967SLB-T
Yes 24-Lead SOIC 31 per tube
A3967SLBTR-T Yes 24-Lead SOIC 1000 per reel
*Pb-based variants are being phased out of the product line. The variants cited in this
footnote are in production but have been determined to be LAST TIME BUY. This
classification indicates that sale of this device is currently restricted to existing
customer applications. The variants should not be purchased for new design
applications because obsolescence in the near future is probable. Samples are no
longer available. Status change: October 31, 2006. Deadline for receipt fo LAST TIME
BUY orders: April 27, 2007. These variants include: A3967SLB and A3967SLBTR.






3967 Datasheet, Funktion
3967
MICROSTEPPING DRIVER
WITH TRANSLATOR
Functional Description (cont’d)
RC Blanking. In addition to the fixed off time of the
PWM control circuit, the CT component sets the compara-
tor blanking time. This function blanks the output of the
current-sense comparator when the outputs are switched
by the internal current-control circuitry. The comparator
output is blanked to prevent false over-current detection
due to reverse recovery currents of the clamp diodes, and/
or switching transients related to the capacitance of the
load. The blank time tBLANK can be approximated by:
tBLANK = 1400CT
Enable Input (ENABLE). This active-low input
enables all of the outputs. When logic high the outputs are
disabled. Inputs to the translator (STEP, DIRECTION,
MS1, MS2) are all active independent of the ENABLE
input state.
Shutdown. In the event of a fault (excessive junction
temperature) the outputs of the device are disabled until
the fault condition is removed. At power up, and in the
event of low VCC, the under-voltage lockout (UVLO)
circuit disables the drivers and resets the translator to the
home state.
Sleep Mode (SLEEP). An active-low control input
used to minimize power consumption when not in use.
This disables much of the internal circuitry including the
outputs. A logic high allows normal operation and startup
of the device in the home position.
Percent Fast Decay Input (PFD). When a STEP
input signal commands a lower output current from the
previous step, it switches the output current decay to either
slow-, fast-, or mixed-decay depending on the voltage
level at the PFD input. If the voltage at the PFD input is
greater than 0.6VCC then slow-decay mode is selected. If
the voltage on the PFD input is less than 0.21VCC then
fast-decay mode is selected. Mixed decay is between
these two levels.
Mixed Decay Operation. If the voltage on the PFD
input is between 0.6VCC and 0.21VCC, the bridge will
operate in mixed-decay mode depending on the step
sequence (see figures). As the trip point is reached, the
device will go into fast-decay mode until the voltage on
the RC terminal decays to the voltage applied to the PFD
terminal. The time that the device operates in fast decay is
approximated by:
tFD = RTCTIn (0.6VCC/VPFD)
After this fast decay portion, tFD, the device will
switch to slow-decay mode for the remainder of the fixed
off-time period.
2.5
TA = +25°C
2.0
SOURCE DRIVER
1.5
Typical output saturation
voltages showing Satlington
sink-driver operation.
1.0
0.5
SINK DRIVER
0
200 300 400 500 600 700
OUTPUT CURRENT IN MILLIAMPERES
Dwg. GP-064-1A
6
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000

6 Page









3967 pdf, datenblatt
3967
MICROSTEPPING DRIVER
WITH TRANSLATOR
STEP
INPUT
100%
70.7%
38.3%
PHASE 1
CURRENT
38.3%
70.7%
100%
100%
70.7%
38.3%
PHASE 2
CURRENT
38.3%
70.7%
100%
Quarter Step Operation
MS1 = L, MS2 = H, DIR = H
SLOW
DECAY
MIXED
DECAY
SLOW
DECAY
MIXED
DECAY
SLOW
DECAY
MIXED
DECAY
MIXED
DECAY
SLOW
DECAY
Dwg. WK-004-17
The mixed-decay mode is controlled by the percent fast
decay voltage (VPFD). If the voltage at the PFD input is
greater than 0.6VCC then slow-decay mode is selected. If
the voltage on the PFD input is less than 0.21VCC then
fast-decay mode is selected. Mixed decay is between
these two levels.
12
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000

12 Page





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