|
|
PDF 3957 Data sheet ( Hoja de datos )
| Número de pieza | 3957 | |
| Descripción | FULL-BRIDGE PWM MICROSTEPPING MOTOR DRIVER | |
| Fabricantes | Allegro MicroSystems | |
| Logotipo |  |
|
Hay una vista previa y un enlace de descarga de 3957 (archivo pdf) en la parte inferior de esta página. Total 16 Páginas | ||
|
No Preview Available !
3957
A3957SLB
NO 1 NC
CONNECT
PFD 2
VBB
REF 3
NO 4 NC
CONNECT
RC 5
GROUND 6
GROUND 7
LOGIC
D3 8
LOGIC
SUPPLY
9 VCC
PHASE 10
D 2 11
NO
CONNECT
12 NC
NC 24
23
NO
CONNECT
LOAD
SUPPLY
22 OUTB
NC 21
NO
CONNECT
20 D 0
19 GROUND
18 GROUND
17 SENSE
NC 16
NO
CONNECT
15 OUTA
NC 14
NO
CONNECT
13 D 1
Dwg. PP-056-4
ABSOLUTE MAXIMUM RATINGS
Load Supply Voltage, VBB . . . . . . . . . 50 V
Output Current, IOUT
(Continuous) . . . . . . . . . . . . . ±1.5 A*
Logic Supply Voltage, VCC . . . . . . . 7.0 V
Logic/Reference Input Voltage Range,
VIN . . . . . . . . . . -0.3 V to VCC + 0.3 V
Sense Voltage, VS . . . . . . . . . . . . . . . 1.0 V
Package Power Dissipation (TA = 25°C), PD
A3957SA . . . . . . . . . . . . . . . . 2.08 W†
A3957SLB . . . . . . . . . . . . . . . 2.23 W†
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.
† Per SEMI G42-88 Specification, Thermal Test
Board Standardization for Measuring Junction-
to-Ambient Thermal Resistance of Semiconductor
Packages..
FULL-BRIDGE PWM
MICROSTEPPING MOTOR DRIVER
The A3957SA and A3957SLB are designed for driving one winding of a
bipolar stepper motor in a microstepping mode. The outputs are rated for
continuous output currents to ±1.5 A and operating voltages to 50 V. Internal
pulse-width modulated (PWM) current control combined with an internal
four-bit nonlinear digital-to-analog converter allows the motor current to be
controlled in full-, half-, quarter-, eighth-, or sixteenth-step (microstepping)
modes. Nonlinear increments minimize the number of control lines necessary
for microstepping. Microstepping provides for increased step resolution, and
reduces torque variations and resonance problems at low speed.
Internal circuitry determines whether the PWM current-control circuitry
operates in a slow (recirculating) current-decay mode, fast (regenerative)
current-decay mode, or in a mixed current-decay mode in which the off time
is divided into a period of fast current decay with the remainder of the fixed
off time spent in slow current decay. The combination of user-selectable
current-sensing resistor and reference voltage, digitally selected output
current ratio; and slow, fast, or mixed current-decay modes provides users
with a broad, variable range of motor control.
Internal circuit protection includes thermal shutdown with hysteresis,
transient-suppression diodes, and crossover current protection. Special
power-up sequencing is not required.
The A3957S— is supplied in a choice of two power packages; a 16-pin
dual-in-line plastic package (suffix ‘A’), and a 24-lead plastic SOIC with
copper heat-sink tabs (suffix ‘LB’). The power tab is at ground potential and
needs no electrical isolation.
FEATURES
s ±1.5 A Continuous Output Current
s 50 V Output Voltage Rating
s Internal PWM Current Control
s 4-Bit Non-Linear DAC for 16-Bit Microstepping
s Satlington™ Sink Drivers
s Fast, Mixed Fast/Slow, and Slow Current-Decay Modes
s Internal Transient-Suppression Diodes
s Internal Thermal-Shutdown Circuitry
s Crossover-Current and UVLO Protection
Always order by complete part number:
Part Number Package
A3957SA
16-pin DIP
A3957SLB
24-lead batwing SOIC
RθJA
60°C/W
56°C/W
RθJC
38°C/W
—
RθJT
—
6°C/W
1 page  
3957
FULL-BRIDGE PWM
MICROSTEPPING
MOTOR DRIVER
ELECTRICAL CHARACTERISTICS at TA = 25˚C, VBB = 5 V to 50 V, VCC = 4.5 V to 5.5 V (unless
otherwise noted.)
Characteristic
Symbol Test Conditions
Min.
Limits
Typ. Max.
Units
Control Circuitry (continued)
Mixed-Decay Comparator
Trip Points
Mixed-Decay Comparator
Input Offset Voltage
Mixed-Decay Comparator
Hysteresis
Reference Input Current
Reference Divider Ratio
Digital-to-Analog Converter
Accuracy*
Current-Sense Comparator
Input Offset Voltage*
Step Reference
Current Ratio
Thermal Shutdown Temp.
Thermal Shutdown Hyst.
VPFD
VIO(PFD)
∆VIO(PFD)
IREF
VREF/VS
—
VIO(S)
SRCR
TJ
∆TJ
Slow Current-Decay Mode
Mixed Current-Decay Mode
Fast Current-Decay Mode
VREF = 0 V to 2.5 V
at trip, D0 = D1 = D2 = D3 = 2 V
1.0 V < VREF ≤ 2.5 V
0.5 V < VREF ≤ 1.0 V
VREF = 0 V
D0 = D1 = D2 = D3 = 0.8 V
D1 = 2 V, D0 = D2 = D3 = 0.8 V
D0 = D1 = 2 V, D2 = D3 = 0.8 V
D2 = 2 V, D0 = D1 = D3 = 0.8 V
D0 = D2 = 2 V, D1 = D3 = 0.8 V
D1 = D2 = 2 V, D0 = D3 = 0.8 V
D0 = D1 = D2 = 2 V, D3 = 0.8 V
D3 = 2 V, D0 = D1 = D2 = 0.8 V
D0 = D3 = 2 V, D1 = D2 = 0.8 V
D1 = D3 = 2 V, D0 = D2 = 0.8 V
D0 = D1 = D3 = 2 V, D2 = 0.8 V
D2 = D3 = 2 V, D0 = D1 = 0.8 V
D0 = D2 = D3 = 2 V, D1 = 0.8 V
D1 = D2 = D3 = 2 V, D0 = 0.8 V
D0 = D1 = D2 = D3 = 2 V
3.5 — — V
1.2 — 2.9 V
— — 0.8 V
— 0 ±20 mV
5.0 25 55 mV
— — ±5.0 µA
— 3.0 —
—
— — ±3.0 %
— — ±4.0 %
— ±16 — mV
—0—
— 17.4 —
— 26.1 —
— 34.8 —
— 43.5 —
— 52.2 —
— 60.9 —
— 69.6 —
— 73.9 —
— 78.3 —
— 82.6 —
— 87.0 —
— 91.3 —
— 95.7 —
— 100 —
— 165 —
— 15 —
%
%
%
%
%
%
%
%
%
%
%
%
%
%
%
°C
°C
* The total error for the VREF/VS function is the sum of the D/A error and the current-sense comparator input offset voltage.
Continued next page…
5 Page 
3957
FULL-BRIDGE PWM
MICROSTEPPING
MOTOR DRIVER
cost of decreased average current accuracy or increased driver
and motor losses.
Mixed Current-Decay Mode. If VPFD is between 1.2 V and
2.9 V, the device will be in a mixed current-decay mode.
Mixed-decay mode allows the user to achieve good current
regulation with a minimum amount of ripple current and motor/
driver losses by selecting the minimum percentage of fast decay
required for their application (see also Stepper Motor Applica-
tions).
As in fast current-decay mode, mixed-decay starts with the sink
and source drivers disabled after the load current reaches ITRIP.
When the voltage at the RC terminal decays to a value below
VPFD, the sink drivers are re-enabled, placing the device in slow
current-decay mode for the remainder of the fixed off time
(figure 2). The percentage of fast decay (PFD) is user deter-
mined by VPFD or two external resistors.
PFD = 100 ln (0.6[R1+R2]/R2)
where
VCC
R1
PFD
R2
Dwg. EP-062-1
Fixed Off-Time. The internal PWM current-control circuitry
uses a one shot to control the time the driver(s) remain(s) off.
The one-shot off-time, tOFF, is determined by the selection of an
external resistor (RT) and capacitor (CT) connected from the RC
timing terminal to ground. The off-time, over a range of values
of CT = 470 pF to 1500 pF and RT = 12 kΩ to 100 kΩ, is
approximated by:
tOFF ≈ RTCT.
When the load current is increasing, but has not yet reached
the sense-current comparator threshold (ITRIP), the voltage on
the RC terminal is approximately 0.6VCC. When ITRIP is
reached, the PWM latch is reset by the current-sense compara-
tor and the voltage on the RC terminal will decay until it
reaches approximately 0.22VCC. The PWM latch is then set,
thereby re-enabling the driver(s) and allowing load current to
increase again. The PWM cycle repeats, maintaining the peak
load current at the desired value.
With increasing values of tOFF, switching losses will
decrease, low-level load-current regulation will improve, EMI
will be reduced, the PWM frequency will decrease, and ripple
current will increase. A value of tOFF can be chosen for optimi-
zation of these parameters. For applications where audible
noise is a concern, typical values of tOFF are chosen to be in the
range of 15 µs to 35 µs.
RC Blanking. In addition to determining the fixed off-time of
the PWM control circuit, the CT component sets the comparator
blanking time. This function blanks the output of the current-
sense comparator when the outputs are switched by the internal
current-control circuitry (or by the PHASE input, or when the
device is enabled with the DAC data inputs). The comparator
output is blanked to prevent false over-current detections due to
reverse recovery currents of the clamp diodes, and/or switching
transients related to distributed capacitance in the load.
During internal PWM operation, at the end of the tOFF time,
the comparator’s output is blanked and CT begins to be charged
from approximately 0.22VCC by an internal current source of
approximately 1 mA. The comparator output remains blanked
until the voltage on CT reaches approximately 0.6VCC. The
blanking time, tBLANK, can be calculated as:
tBLANK = RTCT ln (RT/[RT - 3 kΩ]).
When a transition of the PHASE input occurs, CT is
discharged to near ground during the crossover delay time (the
crossover delay time is present to prevent simultaneous conduc-
tion of the source and sink drivers). After the crossover delay,
CT is charged by an internal current source of approximately 1
mA. The comparator output remains blanked until the voltage
on CT reaches approximately 0.6VCC.
Similarly, when the device is disabled, via the DAC data
inputs, CT is discharged to near ground. When the device is re-
enabled, CT is charged by an internal current source of approxi-
mately 1 mA. The comparator output remains blanked until the
voltage on CT reaches approximately 0.6VCC. The blanking
time, tBLANK′, can be calculated as:
tBLANK′ ≈ 1900 CT.
The minimum recommended value for CT is 470 pF
± 5 %. This value ensures that the blanking time is sufficient to
avoid false trips of the comparator under normal operating
conditions. For optimal regulation of the load current, this
value for CT is recommended and the value of RT can be sized
to determine tOFF.
11 Page | ||
| Páginas | Total 16 Páginas | |
| PDF Descargar | [ Datasheet 3957.PDF ] | |
Hoja de datos destacado
| Número de pieza | Descripción | Fabricantes |
| 3951 | FULL-BRIDGE PWM MOTOR DRIVER | Allegro MicroSystems |
| 3952 | FULL-BRIDGE PWM MOTOR DRIVER | Allegro MicroSystems |
| 3953 | FULL-BRIDGE PWM MOTOR DRIVER | Allegro MicroSystems |
| 3955 | FULL-BRIDGE PWM MICROSTEPPING MOTOR DRIVER | Allegro MicroSystems |
| Número de pieza | Descripción | Fabricantes |
| SLA6805M | High Voltage 3 phase Motor Driver IC. |
 Sanken |
| SDC1742 | 12- and 14-Bit Hybrid Synchro / Resolver-to-Digital Converters. |
 Analog Devices |
|
DataSheet.es es una pagina web que funciona como un repositorio de manuales o hoja de datos de muchos de los productos más populares, |
| DataSheet.es | 2020 | Privacy Policy | Contacto | Buscar |