A3979SLPTR

A3979SLPTR Datasheet


A3979 Microstepping DMOS Driver with Translator

Part Datasheet
A3979SLPTR A3979SLPTR A3979SLPTR (pdf)
Related Parts Information
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A3979 Microstepping DMOS Driver with Translator

A, 35 V output rating Low RDS On outputs Ω source, Ω sink, typical Automatic current decay mode detection/selection to V logic supply voltage range Slow, Fast or Mixed current decay modes Home output Synchronous rectification for low power dissipation Internal UVLO and thermal shutdown circuitry Crossover-current protection

Package 28 lead TSSOP suffix LP with exposed thermal pad

Not to scale

The A3979 is a complete microstepping motor driver with built-in translator, designed as a pin-compatible replacement for the successful A3977, with enhanced microstepping 1/16 step precision. It is designed to operate bipolar stepper motors in full-, half-, quarter-, and sixteenth-step modes, with an output drive capacity of up to 35 V and A. The A3979 includes a fixed off-time current regulator that has the ability to operate in Slow, Fast, or Mixed 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 A3979. It allows the simple input of one pulse on the STEP pin to drive the motor one microstep, which can be either a full step, half, quarter, or sixteenth, depending on the setting of the MS1 and MS2 logic inputs. There are no phase-sequence tables, high-frequency control lines, or complex interfaces to program. The A3979 interface is an ideal fit for applications where a complex microprocessor is unavailable or is overburdened.

Internal synchronous-rectification control circuitry is provided to improve power dissipation during PWM operation. Internal circuit protection includes thermal shutdown with hysteresis, UVLO undervoltage lockout , and crossover-current protection. Special power-on sequencing is not required.

The A3979 is supplied in a low-profile height mm , 28-pin TSSOP with exposed thermal pad. The package is lead Pb free, with 100% matte tin leadframe plating.

Pin-out Diagram

SENSE1 1 HOME 2 DIR 3 OUT1A 4 PFD 5 RC1 6 AGND 7 REF 8 RC2 9 VDD 10 OUT2A 11 MS2 12 MS1 13

SENSE2 14

PWM Timer

Translator and

Control Logic

Charge Pump
28 VBB1 27 SLEEP 26 ENABLE 25 OUT1B 24 CP2 23 CP1 22 VCP 21 PGND 20 VREG 19 STEP 18 OUT2B 17 RESET 16 SR 15 VBB2

AGND and PGND must be connected together externally
26184.23F

A3979

DMOS Microstepping Driver with Translator

Selection Guide Part Number A3979SLPTR-T

Packing 4000 pieces per reel

Absolute Maximum Ratings

Load Supply Voltage Output Current

Output current rating may be limited by duty cycle,

IOUT
ambient temperature, and heat sinking. Under any set of conditions, do not exceed the specified current rating or a
junction temperature of 150°C.

Logic Supply Voltage

Logic Input Voltage Range

Sense Voltage Reference Voltage Operating Ambient Temperature Junction Temperature Storage Temperature

VSENSE VREF TA

TJ max Tstg
tW > 30 ns tW < 30 ns

Range S
to VDD +
to VDD + 1
to 85
to 150

Allegro MicroSystems, LLC
115 Northeast Cutoff, Box 15036
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Datasheet ID: A3979SLPTR 516033