
MICROSTEPPING DMOS DRIVER
WITH TRANSLATOR
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
μ
P 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 hyster-
esis, 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-
lead plastic PLCC with copper batwing tabs (suffix ED), and a thin
(<1.2 mm), 28-lead TSSOP with an exposed thermal pad (suffix LP).
Always order by complete part number: the prefix ‘A’ + the basic part number
(3977) + a suffix letter to indicate operating temperature range + a two-letter
suffix to indicate package style, e.g.,
A3977SLP
.
ABSOLUTE MAXIMUM RATINGS
at T
A
= +25
°
C
Load Supply Voltage, V
BB
.............
35 V
Output Current, I
OUT
..................
±
2.5 A
*
Logic Supply Voltage, V
DD
...........
7.0 V
Logic Input Voltage Range, V
IN
(t
w
>30 ns) ....
-0.3 V to V
DD
+ 0.3 V
(t
w
<30 ns) ..........
-1 V to V
DD
+ 1 V
Sense Voltage, V
SENSE
................
0.5 V
Reference Voltage, V
REF
.................
V
DD
Package Power Dissipation,
P
D
................................
See page 3
Operating Temperature Range, T
A
(A3977Ex)..............
-40
°
C to +85
°
C
(A3977Kx)............
-40
°
C to +125
°
C
(A3977Sx)..............
-20
°
C to +85
°
C
Junction Temperature, T
J
.........
+150
°
C
Storage Temperature Range,
T
S
.........................
-55
°
C to +150
°
C
* 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.
D
2
3977
FEATURES
I
±
2.5 A, 35 V Output Rating
I
Low r
DS(on)
Outputs, 0.45
Source, 0.36
Sink Typical
I
Automatic Current Decay Mode Detection/Selection
I
3.0 V to 5.5 V Logic Supply Voltage Range
I
Mixed, Fast, and Slow Current Decay Modes
I
Home Output
I
Synchronous Rectification for Low Power Dissipation
I
Internal UVLO and Thermal Shutdown Circuitry
I
Crossover-Current Protection
A3977xED
(PLCC)
6
5
4
3
2
1
4
4
4
4
4
7
8
9
10
11
12
13
14
15
16
17
29
30
39
38
37
36
35
34
33
32
31
2
2
2
2
2
2
2
2
2
1
1
Dwg. PP-075-1
GND
GND
SLOGIC
G
G
S
1
O
1
NC
GND
GND
REF
RC
2
NC
O
2
S
2
G
G
G
L
2
O
2
NC
STEP
V
REG
GND
GND
V
CP
CP
1
CP
2
NC
O
1
E
L
S
1
G
C
V
DD
V
BB1
V
BB2
NC
M
2
M
1
NC
S
H
D
PFD
RC
1
÷8
REG
P
T
T
&
R
S
PRELIMINARY INFORMATION
(Subject to change without notice)
February 27, 2003