MICROSTEPPING DMOS DRIVER
WITH TRANSLATOR
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
(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.
Data Sheet
26184.22D
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
■ Low r
DS(on)
Outputs, 0.45 Ω Source, 0.36 Ω Sink Typical
■ 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)
65432144 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
2827262524232221201918
Dwg. PP-075-1
GND
GND
LOGIC
SUPPLY
NC
GND
GND
REF
RC2
NC NC
STEP
VREG
GND
GND
VCP
CP1
CP2
NC
CHARGE PUMP
VDD
VBB1
VBB2
NC
NC
PFD
RC1
÷8
REG
PWM
TIMER
TRANSLATOR
& CONTROL LOGIC
GNDGNDSENSE
1A 1B
ENABLE
LOAD
SUPPLYGND
SLEEPHOMEDIR
OUT OUT
1
1
OUT
2A
SENSE
GNDGND GND
LOAD
SUPPLY
2
OUT
2B
MS
MS
RESET
SR
22 1
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