A3977SLPTR-T - 35V/±2.5A Microstepping DMOS Driver | Allegro MicroSystems
MPN: A3977SLPTR-T ✓ פעילA3977SLPTR-T סקירה
A microstepping driver with translator is an integrated circuit that combines a step/direction interface decoder with dual H-bridge power stages, allowing a host microcontroller to position a bipolar stepper motor at sub-full-step resolutions using only STEP and DIRECTION logic lines, while the IC handles phase sequencing, current chopping, and decay-mode selection internally.
Key features include a fixed off-time PWM current regulator capable of slow-, fast-, and mixed-decay modes (with automatic current-decay mode detection/selection), 3 V to 5.5 V logic supply, 8 V to 35 V motor supply, sync-rectified internal synchronous rectification for lower power dissipation, and a low-power sleep mode. The exposed thermal pad (EP) on the 28-TSSOP package provides a low thermal resistance path to PCB copper, supporting continuous ±2.5 A bipolar operation.
Internally the device uses an integrated DAC-driven current reference, an automatic current-decay state machine that selects slow/fast/mixed decay based on the present PWM pulse width, and synchronous rectification that turns on the low-side DMOS during the current decay portion of each chopping cycle. This combination yields low dissipation at high chopping frequencies and smooth torque at low stepping rates.
Typical applications include bipolar stepper motors in printers, scanners, plotters, factory automation XY stages, medical fluid-handling pumps, and small CNC machines. The 35 V / ±2.5 A envelope and TSSOP-EP footprint also suit 3D-printer axis drives where space is constrained but bipolar torque is required.
When designing with the A3977SLPTR-T, pay particular attention to the exposed-pad soldering - it must be soldered to a sufficiently large copper pour (typically 1 sq inch minimum on each layer) to keep junction temperature within the -20 C to +85 C operating range. Decay-mode programming through the PFD/PFDREF pins and the OSC timing capacitor value directly affects audible noise, current ripple, and torque ripple, and should be tuned per motor.
חלופות תחליף ישיר עבור A3977SLPTR-T — אותו מארז, תואם פין-לפין. חלקים במארז שונה הדורשים עיבוד מחדש של ה-PCB אינם נכללים.
וריאנטים בסדרה זו
דגמים מאותה סדרה התואמים Drop-in עם A3977SLPTR-T (אותו גורם צורה וטביעת רגל) — שונים ב Package, Motor Type, Synchronous Rectification, Mounting Type, Current Control.
A3977SLPTR
✅ Drop-In📋 חלופה להתייחסות (לא בקטלוג)
A3977SLP-T
✅ Drop-In📋 חלופה להתייחסות (לא בקטלוג)
A3977KLP-T
✅ Drop-In📋 חלופה להתייחסות (לא בקטלוג)
A3977SLP
✅ Drop-In📋 חלופה להתייחסות (לא בקטלוג)
A3977KLPTR
✅ Drop-In📋 חלופה להתייחסות (לא בקטלוג)
A3977SLPTR-T דירוגים מרביים ומאפיינים חשמליים
| Motor Type | Bipolar stepper motor |
| Step Modes | Full, half, quarter, eighth |
| תצורת מוצא | Dual full H-bridge (2 outputs) |
| Load Voltage (Motor Supply) | 8 V to 35 V |
| Logic Supply Voltage | 3 V to 5.5 V |
| Output Current (per phase) | ±2.5 A |
| Maximum Output Voltage Rating | 35 V |
| rDS(on) - Source DMOS (typical) | 0.45 ohm |
| rDS(on) - Sink DMOS (typical) | 0.36 ohm |
| Current Control | Fixed off-time PWM with slow/fast/mixed decay |
| יישור סינכרוני | Yes (internal) |
| Sleep Mode | Yes (low-power) |
| Automatic Decay Mode Selection | Yes |
| טמפרטורת פעולה | -20 C to +85 C |
| מארז | 28-pin TSSOP-EP (exposed pad) |
| סוג הרכבה | Surface Mount |
| סטטוס RoHS | Compliant |
תצורת פינים של A3977SLPTR-T
| פין 1 | OUT1B — H-bridge 1 output B |
| פין 2 | OUT1A — H-bridge 1 output A |
| פין 3 | SENSE1 — Current-sense resistor for bridge 1 |
| פין 4 | GND — Analog/digital ground |
| פין 5 | PFD — Mixed-decay programming |
| פין 6 | PFDREF — Mixed-decay reference |
| פין 7 | ROSC — Off-time PWM capacitor |
| פין 8 | DIR — Direction logic input |
| פין 9 | STEP — Step pulse logic input |
| פין 10 | MS1 — Microstep select 1 |
| פין 11 | MS2 — Microstep select 2 |
| פין 12 | ENABLE — Enable logic input |
| פין 13 | SLEEP — Sleep mode logic input |
| פין 14 | VDD — Logic supply 3 V to 5.5 V |
| פין 15 | NC — Not connected (per datasheet) |
| פין 16 | NC — Not connected (per datasheet) |
| פין 17 | VBB — Motor supply 8 V to 35 V |
| פין 18 | CP1 — Charge pump capacitor 1 |
| פין 19 | CP2 — Charge pump capacitor 2 |
| פין 20 | VREG — Internal regulator decoupling |
| פין 21 | NC — Not connected (per datasheet) |
| פין 22 | OUT2A — H-bridge 2 output A |
| פין 23 | OUT2B — H-bridge 2 output B |
| פין 24 | SENSE2 — Current-sense resistor for bridge 2 |
| פין 25 | GND — Power ground |
| פין 26 | NC — Not connected (per datasheet) |
| פין 27 | NC — Not connected (per datasheet) |
| פין 28 | NC — Not connected (per datasheet) |
יישומים טיפוסיים
A3977SLPTR-T מתאים עבור 6 יישוםs: Bipolar Stepper Motor Drive in 3D Printers, Office Automation: Printers, Scanners, Plotters, Factory Automation XY Stages, Medical Fluid-Handling Pumps, Small CNC Routers and Engravers, Textile and Sewing Machinery.
Bipolar Stepper Motor Drive in 3D Printers
The A3977SLPTR-T's 35 V / ±2.5 A bipolar envelope and built-in microstepping translator (up to 1/8 step) make it a strong fit for the X, Y, Z, and extruder axes of desktop and prosumer 3D printers. Placed between a 12 V or 24 V motor bus and the bipolar stepper, the IC handles phase sequencing, current chopping, and automatic slow/fast/mixed-decay selection from a single STEP/DIRECTION pair - eliminating firmware-side phase tables. The TSSOP-EP footprint lets designers shrink the carriage PCB compared with the older PLCC A3977 variants. Compared with discrete L297 + L298 stacks, the integrated DMOS H-bridges cut quiescent losses and EMI from synchronous rectification, improving print resolution at low stepping rates.
מומלץ
Office Automation: Printers, Scanners, Plotters
The A3977SLPTR-T was designed for office-automation paper-transport and print-head positioning axes, and that heritage makes it ideal for laser-printer paper-path steppers, scanner carriage drives, and plotter pen-lift mechanisms. The 8 V to 35 V motor supply range covers both 24 V and 30 V office rails, while 3 V to 5.5 V logic directly interfaces with 3.3 V ASICs. Per the Allegro datasheet, automatic decay-mode selection adapts to varying motor speeds during bidirectional moves, reducing audible resonance and torque ripple. Engineers benefit from the synchronous rectification that keeps dissipation low during long holding periods between pages.
מומלץ
Factory Automation XY Stages
In factory-automation pick-and-place, dispensing, and inspection XY stages, the A3977SLPTR-T drives NEMA 17 or NEMA 23 bipolar steppers with smooth 1/8-step microstepping and tight current control. Per the Allegro datasheet, the fixed off-time PWM regulator with slow/fast/mixed-decay options enables designers to tune the drive profile for each motor-load combination, minimizing vibration during high-acceleration moves. The 35 V rating supports 24 V industrial rails with margin, while the exposed-pad TSSOP package provides the thermal performance needed for continuous duty cycles in 24/7 production environments.
מומלץ
Medical Fluid-Handling Pumps
Peristaltic and syringe pumps used in diagnostic and infusion equipment benefit from the A3977SLPTR-T's quiet microstepping operation. Per the Allegro datasheet, automatic decay-mode detection smooths current transitions between microsteps, reducing the audible noise that disturbs clinical environments. The 3 V to 5.5 V logic supply interfaces with battery-backed MCUs, while the 8 V to 35 V motor range covers both bench-top 12 V and ambulatory 24 V pump rails. The exposed-pad TSSOP package fits compact pump-controller boards where PLCC variants cannot.
מומלץ
Small CNC Routers and Engravers
Hobbyist and light-industrial CNC routers use the A3977SLPTR-T to drive the X, Y, and Z bipolar steppers from a 24 V or 30 V supply. Per the Allegro datasheet, the 1/8-step microstepping and automatic decay-mode control reduce resonance-induced surface marks on routed workpieces, while the ±2.5 A output supports NEMA 17 motors for spindle-positioning axes. Designers value the TSSOP-EP form factor for retrofit boards replacing older L297 + L298 solutions, and the synchronous rectification reduces heatsink requirements.
מומלץ
Textile and Sewing Machinery
Industrial sewing, embroidery, and textile-cutting machines require quiet, vibration-free stepper motion, and the A3977SLPTR-T's automatic decay-mode selection and 1/8-step microstepping deliver the smooth torque profiles these applications demand. Per the Allegro datasheet, the 3 V to 5.5 V logic supply interfaces directly with modern machine controllers, while the 35 V motor rail covers 24 V and 30 V sewing-machine buses. The exposed-pad TSSOP package is robust enough for the high-vibration sewing environment when properly soldered to chassis-grounded copper.
מומלץ
סיכום מוצרים מומלצים
נתוני עזר הנדסיים עבור A3977SLPTR-T — השוואה, הנחיות תכנון ומידע על תאימות.
מדריך בחירה
השוואה עם חלופות
| פרמטר | מוצר זה | A3977SLPTR | A3977SLP-T | A3977KLP-T | A3977SLP | A3977KLPTR |
|---|---|---|---|---|---|---|
| Package | 28-TSSOP-EP | 28-TSSOP-EP (same) | 28-TSSOP-EP (same) | 44-PLCC | 28-TSSOP-EP (same) | 44-PLCC |
| Brand | Allegro MicroSystems | Allegro MicroSystems | Allegro MicroSystems | Allegro MicroSystems | Allegro MicroSystems | Allegro MicroSystems |
| Output Current (per phase) | ±2.5 A | ±2.5 A | ±2.5 A | ±2.5 A | ±2.5 A | ±2.5 A |
| Motor Supply Voltage | 8 V to 35 V | 8 V to 35 V | 8 V to 35 V | 8 V to 35 V | 8 V to 35 V | 8 V to 35 V |
| rDS(on) Source / Sink | 0.45 ohm / 0.36 ohm | 0.45 ohm / 0.36 ohm | 0.45 ohm / 0.36 ohm | 0.45 ohm / 0.36 ohm | 0.45 ohm / 0.36 ohm | 0.45 ohm / 0.36 ohm |
| Step Modes | Full / Half / Quarter / Eighth | Full / Half / Quarter / Eighth | Full / Half / Quarter / Eighth | Full / Half / Quarter / Eighth | Full / Half / Quarter / Eighth | Full / Half / Quarter / Eighth |
| Synchronous Rectification | Yes | Yes | Yes | Yes | Yes | Yes |
| Shipping Carrier | Tape & Reel (-T) | Tape & Reel (no -T) | Tray | Tray | Commercial packing | Tape & Reel |
| Operating Temperature | -20 C to +85 C | -20 C to +85 C | -20 C to +85 C | -20 C to +85 C | -20 C to +85 C | -20 C to +85 C |
מבדילים עיקריים
- Automatic current-decay mode detection (slow / fast / mixed) (לעומתA3977SLP-T (tray packing variant))
- Internal synchronous rectification (לעומתDiscrete L297 + L298 stacks)
- Built-in microstepping translator with STEP/DIR interface (לעומתA3977KLP-T (44-PLCC package))
- 35 V / ±2.5 A in a TSSOP-EP footprint (לעומתA3938SLDTR-T (Allegro 3-phase BLDC))
הערות תכנון
Estimated: at VBB=24 V, full-scale phase current of 2.5 A and worst-case rDS(on) of 0.5 ohm source plus 0.4 ohm sink, conduction loss per phase is roughly (0.5+0.4) x (2.5^2) / 2 ~ 2.8 W. Continuous bipolar operation at ±2.5 A therefore requires the exposed thermal pad to be soldered to at least 1 square inch of 2-oz copper on top and inner PCB layers; without this, junction temperature will exceed the 85 C ambient ceiling. Use thermal vias to inner copper planes for additional margin in enclosed housings.
Per the Allegro datasheet, place the charge-pump capacitor between CP1 and CP2 as close to the IC as possible, using a 0.1 uF X7R ceramic rated for the full motor supply voltage. Decouple VBB with a bulk electrolytic (>=47 uF, 50 V rating) plus a 0.1 uF ceramic directly at the pin; logic VDD likewise needs a 0.1 uF ceramic plus 10 uF bulk. The SENSE pins carry fast switching currents - route the SENSE traces as a Kelvin pair directly to the sense resistor to avoid ground-loop induced current-control error.
Keep motor-phase traces (OUT1A/B, OUT2A/B) short and wide to minimize inductance; each phase transition can ring above 35 V and damage the DMOS outputs if the trace loop is too long. Place the sense resistor in the return path of the bridge, not in the high-side rail - the A3977 uses low-side current sensing. Route STEP, DIR, ENABLE, and SLEEP away from the motor traces to prevent logic corruption from capacitive coupling.
Do not operate the A3977SLPTR-T with VBB below 8 V - the internal charge pump and DMOS gate drive will not fully enhance, leading to high rDS(on) and thermal runaway. Do not leave the SENSE pin floating; if unused for one bridge, the SENSE line must still be tied to ground through the sense resistor. Do not apply STEP pulses before VDD has ramped past 3 V and VBB past 8 V; the datasheet specifies a power-on sequence that must be observed to avoid spurious phase events.
The STEP input is edge-sensitive; mechanical switch bounce on manual jog inputs must be filtered to <=1 us. For cables longer than ~50 mm between MCU and driver, add a 1 kohm series resistor and 100 pF to ground at the STEP pin for EMI hardening. Per the Allegro datasheet, the DIR-to-STEP setup time is ~200 ns - allow at least 250 ns in firmware before issuing STEP edges to guarantee correct direction decoding.
מידע על תאימות
Per Allegro MicroSystems product listings on DigiKey and Mouser, the A3977SLPTR-T is RoHS-compliant and lead-free. Not AEC-Q100 qualified; this part targets industrial, consumer, and office-automation motor-control applications, not automotive.
