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PDF UC3717 Data sheet ( Hoja de datos )
| Número de pieza | UC3717 | |
| Descripción | Stepper Motor Drive Circuit | |
| Fabricantes | Unitrode | |
| Logotipo |  |
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Stepper Motor Drive Circuit
UC1717
UC2717
UC3717
FEATURES
• Half-step and Full-step Capability
• Bipolar Constant Current Motor Drive
• Built-in Fast Recovery Schottky
Commutating Diodes
• Wide Range of Current Control 5-1000mA
• Wide Voltage Range 10-45V
• Designed for Unregulated Motor Supply
Voltage
DESCRIPTION
The UC3717 has been designed to control and drive the current in
one winding of a bipolar stepper motor. The circuit consists of an LS-
TTL-compatible logic input, a current sensor, a monostable and an
output stage with built-in protection diodes. Two UC3717s and a few
external components form a complete control and drive unit for LS-
TTL or micro-processor controlled stepper motor systems.
The UC1717 is characterized for operation over the full military tem-
perature range of -55°C to +125°C, the UC2717 is characterized for
-25°C to +85°C, and the UC3717 is characterized for 0°C to +70°C.
• Current Levels can be Selected in Steps
or Varied Continuously
• Thermal Overload Protection
ABSOLUTE MAXIMUM RATINGS (Note 1)
Voltage
Logic Supply, VCC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7V
Output Supply, VM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45V
Input Voltage
Logic Inputs (Pins 7, 8, 9). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6V
Analog Input (Pin 10) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Vcc
Reference Input (Pin 11) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15V
Input Current
Logic Inputs (Pins 7, 8, 9) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -10mA
Analog Inputs (Pins 10, 11) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -10mA
Output Current (Pins 1, 15) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ±1A
Junction Temperature, TJ. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . +150°C
Storage Temperature Range, TS . . . . . . . . . . . . . . . . . . -55°C to +150°C
Note 1: All voltages are with respect to ground, Pins
4,5, 12, 13. Pin numbers refer to DIL-16 package. Cur-
rents are positive into, negative out of the specified ter-
minal.
Note 2: Consult Packaging Section of Databook for in-
formation on thermal limitations and considerations of
package.
BLOCK DIAGRAM
7/95
1 page  
FUNCTIONAL DESCRIPTION (cont.)
Overload Protection: The circuit is equipped with a
thermal shutdown function, which will limit the junction
temperature by reducing the output current. It should be
noted however, that a short circuit of the output is not
permitted.
Operation: When the voltage is applied across the motor
winding the current rises linearly and appears across the
external sense resistor as an analog voltage. This volt-
age is fed through a low pass filter RC, CC to the voltage
comparator (pin 10). At the moment the voltage rises be-
yond the comparator threshold voltage the monostable is
triggered and its output turns off the sink transistors. The
current then circulates through the source transistor and
the appropriate Schottky diode. After the one shot has
timed out, the sink transistsor is turned on again and the
procedure repeated until a current reverse command is
given. By reversing the logic level of the phase input (pin
8), both active transistors are being turned off and the
opposite pair turned on. When this happens the current
must first decay to zero before it can reverse. The cur-
rent path then provided is through the two diodes and the
power-supply. Refer to Figure 7. It should be noted at
this time that the slope of the current decay is steeper,
and this is due to the higher voltage build up across the
winding. For better speed performance of the stepping
motor at half step mode, the phase logic level should be
changed at the same time the current inhibit is applied. A
typical current wave form is shown in Figure 8.
Figure 8
APPLICATIONS
A typical chopper drive for a two phase bipolar perma-
nent magnet or hybrid stepping motor is shown in Figure
9. The input can be controlled by a microprocessor, TTL,
LS or CMOS logic.
UC1717
UC2717
UC3717
Figure 9
The timing diagram in Figure 10 shows the required sig-
nal input for a two phase, full step, stepping sequence.
Figure 11 shows a one phase, full step, stepping se-
quence, commonly referred to as wave drive. Figure 12
shows the required input signal for a one phase-two
phase stepping sequence called half-stepping.
The circuit of Figure 13 provides the signal shown in Fig-
ure 10, and in conjunction with the circuit shown in Fig-
ure 9, will implement a pulse-to-step two phase, full step,
bidirectional motor drive.
The schematic of Figure 14 shows a pulse to half step
circuit generating the signal shown in Figure 12. Care
has been taken to change the phase signal the same
time the current inhibit is applied. This will allow the cur-
rent to decay faster and therefore enhance the motor
performance at higher step rates.
Using the UC3717 to drive the L298 provides a uniquely
packaged state-of-the-art high power stepper motor con-
trol and drive. See Figure 15.
5
5 Page | ||
| Páginas | Total 9 Páginas | |
| PDF Descargar | [ Datasheet UC3717.PDF ] | |
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