A3955SB-T Allegro Microsystems Inc, A3955SB-T Datasheet

Page 1

Full-Bridge PWM Microstepping Motor Driver This device is in production, however, it has been deemed Pre-End of Life. The product is approaching end of life. Within a minimum of 6 months, the device will enter its final, Last Time Buy, ...

Page 2

Full-Bridge PWM Microstepping Motor Driver Features and Benefits ▪ ±1.5 A continuous output current ▪ output voltage rating ▪ Internal PWM current control ▪ 3-bit nonlinear DAC ▪ Fast, mixed fast/slow, and slow current-decay modes ▪ Internal transient-suppression ...

Page 3

... Special power-up sequencing is not required. The A3955 is supplied in a choice of two power packages; a 16-pin dual-in-line plastic package with copper heat-sink tabs (suffix ‘B’), Selection Guide Part Number A3955SB-T 16-pin DIP with exposed thermal tabs A3955SLBTR-T 16-pin SOICW with internally fused pins Absolute Maximum Ratings ...

Page 4

A3955 Full-Bridge PWM Microstepping Motor Driver ELECTRICAL CHARACTERISTICS at T (unless otherwise noted.) Characteristic Power Outputs Load Supply Voltage Range Output Leakage Current Output Saturation Voltage (Forward or Reverse Mode) Sense Current Offset Clamp Diode Forward Voltage (Sink or Source) ...

Page 5

A3955 Full-Bridge PWM Microstepping Motor Driver ELECTRICAL CHARACTERISTICS (continued 5.5 V (unless otherwise noted. ) Characteristic Control Circuitry Logic Supply Voltage Range Reference Voltage Range UVLO Enable Threshold UVLO Hysteresis Logic Supply Current Logic Input Voltage Logic Input ...

Page 6

A3955 Full-Bridge PWM Microstepping Motor Driver ELECTRICAL CHARACTERISTICS (continued 5.5 V (unless otherwise noted. ) Characteristic Control Circuitry (cont’d) Thermal Shutdown Temp. Thermal Shutdown Hysteresis AC Timing PWM RC Fixed Off-time PWM Turn-Off Time t PWM Turn-On Time ...

Page 7

... A3955 Full-Bridge PWM Microstepping Motor Driver Note the A3955SB (DIP) and the A3955SLB (SOIC) are electrically identical and share a common terminal number assignment. Terminal Name Description 1 PFD (Percent Fast Decay) The analog input used to set the current-decay mode. 2 REF ( The parallel combination of external resistor R PWM current regulator ...

Page 8

A3955 Full-Bridge PWM Microstepping Motor Driver Functional Description Two A3955 full-bridge PWM microstepping motor drivers are needed to drive the windings of a bipolar stepper motor. Internal pulse width modulated (PWM) control circuitry regulates each motor winding current. The peak ...

Page 9

A3955 Full-Bridge PWM Microstepping Motor Driver reference value, resulting in increased motor performance in microstepping applications. For a given level of ripple current, slow decay affords the lowest PWM frequency, which reduces heating in the motor and driver IC due ...

Page 10

A3955 Full-Bridge PWM Microstepping Motor Driver . If V Mixed Current-Decay Mode and 3.1 V, the device will mixed current-decay mode. Mixed-decay mode allows the user to achieve good current regulation with a minimum amount of ripple ...

Page 11

A3955 Full-Bridge PWM Microstepping Motor Driver Thermal-protection circuitry Thermal Considerations. turns off all output transistors when the junction temperature reaches approximately +165°C. This is intended only to protect the device from failures due to excessive junction temperatures and should not ...

Page 12

A3955 Full-Bridge PWM Microstepping Motor Driver Full Half Quarter Eighth Step Step Step Step ...

Page 13

A3955 Full-Bridge PWM Microstepping Motor Driver A 100 92.4 83.1 70.7 55.5 38.2 19 19.5 38.2 55.5 70.7 CURRENT IN PER CENT Figure 5 — Current and Displacement Vectors MAXIMUM FULL-STEP FULL STEP B 83.1 92.4 100 Dwg. ...

Page 14

A3955 Full-Bridge PWM Microstepping Motor Driver 1.27 MIN +0.25 1.52 –0.38 10.30±0. 16X 0.10 C 1.27 0.41 ±0.10 Copyright ©1997-2010, Allegro MicroSystems, Inc. Allegro MicroSystems, Inc. reserves the right to make, from ...