A4989SLDTR-T Allegro Microsystems Inc, A4989SLDTR-T Datasheet - Page 13

• Manufacturer Part Number: A4989SLDTR-T
• Description: DUAL FULL BRDG MOSFET DRVR W/MICROSTEP TRANS
• Manufacturer: Allegro Microsystems Inc

Specifications of A4989SLDTR-T

• Applications: Stepper Motor Controller, 2-Phase
• Number Of Outputs: 1
• Voltage - Load: 12 V ~ 50 V
• Voltage - Supply: 3 V ~ 5.5 V
• Operating Temperature: -20°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 38-TFSOP (0.173", 4.40mm Width)
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Current - Output: -
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Other names: 620-1389-2

A4989
motors having low values of DC phase resistance, the minimum
current that can be controlled can be higher than the target value
required in some microstepping modes. Errors in the average
current amplitude delivered to the phases of a motor can lead to
positional errors in the holding condition and/or excessive torque
ripple and acoustic noise at low speeds.
The conditions for the loss of current control due to this effect are
just after a current zero crossing, as the magnitude of the cur-
Figure 7. A 4989 driving the same motor as in figure 6, using these
settings: MS1=MS2=1, PFD1=PFD2= 1
Figure 6. An example of missed steps when
motor at low stepping speeds
Current Control
Correct
Missed Steps
Phase Voltage (2B)
Phase Voltage (2A)
Phase Voltage (2B)
Phase Voltage (2A)
Phase Current (2)
Phase Current (2)
Step Voltage
Step Voltage
Dual Full-Bridge MOSFET Driver
rent increases. Introducing mixed decay over the range of steps
affected enhances current control. Because the requirements are
closely related to the microstep settings used, the relationship
between MSx and PFDx is tabulated in table 2 for clarity.
The overall result is an extension of the minimum current control
range the 4989 can achieve. The effect can be seen clearly in
figures 6 and 7, below.
with Microstepping Translator
1
/
16
microstepping a
115 Northeast Cutoff
1.508.853.5000; www.allegromicro.com
Allegro MicroSystems, Inc.
Worcester, Massachusetts 01615-0036 U.S.A.
13