MICROSTEPPING DMOS DRIVER

WITH TRANSLATOR

ABSOLUTE MAXIMUM RATINGS

Package Power Dissipation,

(A3977Kx) ............ -40°C to +125°C

(A3977Sx) .............. -20°C to +85°C

Storage Temperature Range,

* 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.

3977

The A3977xED and A3977xLP are complete microstepping motor drivers

with built-in translator. They are designed to operate bipolar stepper motors in

full-, half-, quarter-, and eighth-step modes, with output drive capability of 35

V and ±2.5 A. The A3977 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 A3977. By

simply inputting one pulse on the STEP input the motor will take one step

(full, half, quarter, or eighth depending on two logic inputs). There are no

phase-sequence tables, high-frequency control lines, or complex interfaces to

program. The A3977 interface is an ideal fit for applications where a complex

µP is unavailable or over-burdened.

Internal synchronous-rectification control circuitry is provided to improve

power dissipation during PWM operation.

Internal circuit protection includes thermal shutdown with hysteresis,

under-voltage lockout (UVLO) and crossover-current protection. Special

power-up sequencing is not required.

The A3977 is supplied in a choice of two power packages, a 44-pin

plastic PLCC with copper batwing tabs (suffix ED), and a thin (<1.2 mm), 28-

pin TSSOP with an exposed thermal pad (suffix LP). The SLP package is

available in a lead-free version (100% matte tin leadframe).

FEATURES

■

±2.5 A, 35 V Output Rating

■

■

Automatic Current Decay Mode Detection/Selection

■

3.0 V to 5.5 V Logic Supply Voltage Range

■

Mixed, Fast, and Slow Current Decay Modes

■

Home Output

■

Synchronous Rectification for Low Power Dissipation

■

Internal UVLO and Thermal Shutdown Circuitry

■

Crossover-Current Protection

A3977xED

(PLCC)

65

43

21

44

43

42

41

40

7

8

9

10

11

12

13

14

15

16

17

29

30

39

38

37

36

35

34

33

32

31

28

27

26

25

24

23

22

21

20

19

18

Dwg. PP-075-1

GND

GND

LOGIC

SUPPLY

NC

GND

GND

REF

NC

NC

STEP

GND

GND

NC

NC

NC

PFD

÷8

REG

PWM

TIMER

Always order by complete part number:

Part Number

Package

A3977KED

44-pin PLCC

A3977KLP

28-pin TSSOP

A3977SED

44-pin PLCC

A3977SED-T

44-pin PLCC; Lead-free

A3977SLP

28-pin TSSOP

A3977SLP-T

28-pin TSSOP; Lead-free