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Allegro MicroSystems A4975SB-T
- Part No.:
- A4975SB-T
- Manufacturer:
- Allegro MicroSystems
- Category:
- Motor Drivers, Controllers
- Package:
- 16-PowerDIP (0.300", 7.62mm)
- Datasheet:
-
A4975SB-T.pdf
- Description:
- IC MTR DRV BIPOLR 4.5-5.5V 16DIP
- Quantity:
- Payment:
- Shipping:
Inventory:3,997
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Product details
Overview
A4975SB-T from Allegro MicroSystems is a full-bridge PWM microstepping motor driver IC designed to control one winding of a bipolar stepper motor. It delivers ±1.5 A continuous output current at up to 50 V load supply, implements internal 3-bit nonlinear DAC-based current control for full/half/quarter/eighth-step modes, and supports user-selectable fast/mixed/slow current decay via analog PFD input - used in precision motion control systems for CNC equipment and automated laboratory instruments.
For engineers reviewing the A4975SB-T datasheet, A4975SB-T pinout, A4975SB-T application, or A4975SB-T equivalent, key selection considerations include its discontinued status, DIP-16 thermal-tab package, fixed off-time PWM architecture with RC timing, thermal shutdown at 165°C, and compatibility with sinusoidal microstepping drive profiles requiring precise current decay mode tuning.
Technical Context
The A4975SB-T integrates a full H-bridge power stage with internal PWM current regulation, where peak current is set by external sense resistor RS, reference voltage VREF, and 3-bit DAC inputs (D0–D2). Its current decay behavior is determined by the analog PFD input voltage: ≥3.5 V enables slow decay (recirculating), ≤0.8 V enables fast decay (regenerative), and 1.1–3.1 V enables mixed decay (fast then slow).
Timing is governed by external RT/CT network connected to the RC pin, setting both fixed off-time (tOFF ≈ RTCT) and comparator blanking time. Internal protection includes thermal shutdown (165°C trip, 15°C hysteresis), UVLO (3.7 V enable threshold), and crossover-current prevention via 500 ns dead time on PHASE transitions.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Current | ±1.5 A continuous - defines maximum motor phase current without forced cooling or derating |
| Load Supply Voltage | 50 V max - supports stepper motors with high back-EMF or wide supply rails |
| Logic Supply Voltage | 4.5–5.5 V - requires stable 5 V rail; not compatible with 3.3 V logic |
| PWM Off-Time Range | 18.2–22.3 µs (typ. 20.2 µs) with RT = 43 kΩ, CT = 470 pF - sets minimum switching frequency and ripple trade-off |
| Current Decay Modes | Slow / Mixed / Fast - selected via analog PFD voltage; determines recirculation path, ripple magnitude, and regulation fidelity |
| DAC Resolution | 3-bit nonlinear - provides eight discrete current ratios (0–100%) optimized for microstepping sine-wave fidelity |
| Junction Temp Limit | 150°C max operating, 165°C shutdown - requires copper-tab heatsinking in DIP-16 package (RθJA = 43°C/W) |
Pinout & Package
Package: 16-pin DIP with exposed copper thermal tabs (Package B), lead-free with 100% matte tin plating. Thermally enhanced pins (4,5,12,13) are grounded and require no electrical isolation.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 (PFD) | Analog decay mode control | Voltage input selecting slow/mixed/fast current decay; critical for microstepping waveform shaping |
| 2 (REF) | Reference voltage input | Set point for DAC-based current limit; combined with RS and D0–D2 to define ITRIP ≈ SRCR × VREF/(5×RS) |
| 3 (RC) | RC timing node | Connects external RT/CT to set PWM fixed off-time and comparator blanking duration |
| 4,5,12,13 (GROUND) | Power return paths | Common ground for logic (VCC) and load (VBB); thermally tied to exposed tabs for heat dissipation |
| 6 (VCC) | Logic supply | 5 V nominal supply for internal logic; must be decoupled near pin; UVLO active below 3.7 V |
| 7 (PHASE) | Direction control | Digital input toggling current polarity in motor winding; includes 500 ns internal dead time |
| 8–9,14 (D2,D1,D0) | DAC data inputs | 3-bit LSB/MSB control for eight-step current ratio selection (0–100%); all low disables outputs |
| 10,15 (OUTA,OUTB) | H-bridge outputs | High-side/low-side connections to stepper motor winding; rated for 50 V, ±1.5 A |
| 11 (SENSE) | Current sense return | Connection point for external sense resistor RS; feeds current-sense comparator input |
| 16 (VBB) | Motor supply input | High-voltage rail for motor winding; separate from logic supply to minimize noise coupling |
Key Features
| Feature | Design Value |
|---|---|
| Nonlinear 3-bit DAC | Optimizes microstep current steps for sinusoidal fidelity - e.g., 70.7% and 55.5% ratios match √2/2 and √3/2 for quarter-step resolution |
| User-configurable decay modes | Single analog PFD input selects decay profile - avoids need for digital mode control lines while enabling ripple vs. regulation trade-offs |
| Integrated thermal shutdown | 165°C trip with 15°C hysteresis - protects against sustained overload or inadequate heatsinking in DIP-16 package |
| Internal blanking circuitry | RC capacitor sets comparator blanking time - prevents false overcurrent trips during switching transients or PHASE transitions |
| UVLO and crossover protection | 3.7 V VCC enable threshold + 500 ns PHASE dead time - ensures safe power-up sequencing and prevents shoot-through |
Applications
| Industrial CNC Positioning | Laboratory Automation Stages |
|---|---|
Use Scenario: Precise open-loop positioning of X-Y translation stages in optical alignment systems requiring sub-micron repeatability. IC Role / Device Role / Timing Role: Full-bridge driver for one motor phase; generates microstepped current waveforms synchronized to PHASE/DAC updates at ≤20 kHz. Use Value: Nonlinear DAC steps and mixed-decay mode reduce torque ripple and resonance at low speeds, improving positional stability without closed-loop feedback. | Use Scenario: Motion control in robotic liquid handlers performing multi-well plate assays with variable acceleration profiles. IC Role / Device Role / Timing Role: Bipolar stepper phase controller; uses PFD voltage modulation to adapt decay mode dynamically during acceleration/deceleration phases. Use Value: Fast decay during rapid current decrease prevents tailing; slow decay during ramp-up maintains average current accuracy and minimizes audible noise. |
| Medical Imaging Actuators | 3D Printing Extruder Control |
Use Scenario: Fine-pitch linear actuation in MRI-compatible sample positioning modules where EMI and thermal management are critical. IC Role / Device Role / Timing Role: Isolated motor winding driver; operates from 24 V VBB with external 0.5 Ω sense resistor and 5 V VCC rail. Use Value: Exposed thermal tabs in DIP-16 package enable direct mounting to metal chassis, achieving RθJA = 43°C/W for reliable operation at 1.2 A continuous. | Use Scenario: Microstepped extruder motor control in desktop FDM printers requiring smooth filament feed at low RPM with minimal vibration. IC Role / Device Role / Timing Role: Eighth-step current controller; DAC inputs sequenced via MCU GPIO to generate sinusoidal current profiles matching stepper rotor position. Use Value: Eighth-step resolution reduces step-induced resonance and layer banding artifacts, directly improving print surface finish quality. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar full-bridge PWM microstepping motor driver applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| A4975SLBTR-T | Identical electrical functionality; SOICW-16 package with internally fused pins instead of DIP-16 with exposed tabs | Surface-mount assembly; lower profile; higher RθJA (67°C/W) requires more PCB copper area for thermal management | Select for new designs requiring RoHS-compliant SMT manufacturing and lifecycle continuity |
| TB6600HG | Higher 4.5 A output rating; 5–42 V VBB range; fixed decay mode only (no PFD analog control) | Supports larger stepper motors; lacks mixed-decay flexibility for optimized microstepping waveform fidelity | Select when higher current capability is required and decay mode adaptability is not critical |
Compared with A4975SB-T, A4975SLBTR-T offers identical microstepping performance in an SMT package with different thermal characteristics, while TB6600HG provides higher current but sacrifices the analog PFD-controlled decay mode essential for precision sinusoidal current profiling.
Availability
A4975SB-T is available at Aetrix Electronics and suitable for legacy system repair, end-of-life component replacement, and existing customer transition support requiring stable component supply for industrial motion control, laboratory instrumentation, and medical device maintenance programs.
Supply support for A4975SB-T includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.
Manufacturer
Allegro MicroSystems is a U.S.-based designer and manufacturer of high-performance magnetic sensing and power IC solutions, headquartered in Manchester, NH.
The A4975SB-T belongs to Allegro's full-bridge motor driver product line, engineered specifically for bipolar stepper motor microstepping applications demanding precise current control, thermal robustness, and flexible decay mode selection in industrial and instrumentation environments.
FAQ
Is the A4975SB-T still in production?
No, the A4975SB-T is obsolete and no longer in production. Allegro MicroSystems discontinued it effective July 2, 2018, and samples are no longer available. For new designs, Aetrix Electronics recommends the pin-compatible A4975SLBTR-T as the designated replacement. The A4975SB-T remains supported for legacy repair and transition use only.
What package type does the A4975SB-T use?
The A4975SB-T uses a 16-pin dual in-line plastic package (DIP) with exposed copper thermal tabs (Package B). This through-hole package features grounded thermal tabs on pins 4, 5, 12, and 13 for direct heatsinking to a metal chassis or PCB copper pour, achieving RθJA = 43°C/W under specified conditions.
How does the PFD pin control current decay mode in the A4975SB-T?
The PFD (Percent Fast Decay) pin on the A4975SB-T accepts an analog voltage to select current decay behavior: ≥3.5 V enables slow decay (recirculating), ≤0.8 V enables fast decay (regenerative), and 1.1–3.1 V enables mixed decay (fast then slow). This single-pin analog control eliminates the need for multiple digital mode-select lines while enabling fine-tuned ripple-regulation trade-offs in microstepping applications.
What is the maximum continuous output current rating for the A4975SB-T?
The A4975SB-T is rated for ±1.5 A continuous output current per phase. This rating assumes adequate heatsinking via the exposed thermal tabs in the DIP-16 package and operation within the –20°C to +85°C ambient temperature range. Exceeding this current without thermal derating risks activation of the 165°C thermal shutdown circuit.
Can the A4975SB-T be used for full-step, half-step, and microstepping modes?
Yes, the A4975SB-T supports full-step, half-step, quarter-step, and eighth-step (microstepping) operation via its internal 3-bit nonlinear DAC. The DAC inputs (D0–D2) select eight discrete current ratios (0–100%), and combined with PHASE input sequencing, enable precise sinusoidal current profiling - critical for reducing resonance and improving low-speed torque uniformity in stepper motor applications.
A4975SB-T Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Allegro MicroSystems
- Series:
- -
- Package/Case:
- 16-PowerDIP (0.300", 7.62mm)
- Packaging:
- Tube
- Product Status:
- Obsolete
- Motor Type - Stepper:
- Bipolar
- Motor Type - AC, DC:
- -
- Function:
- Driver - Fully Integrated, Control and Power Stage
- Output Configuration:
- Half Bridge (2)
- Interface:
- Parallel
- Technology:
- Power MOSFET
- Step Resolution:
- 1, 1/2, 1/4, 1/8
- Applications:
- General Purpose
- Current - Output:
- 1.5A
- Voltage - Supply:
- 4.5V ~ 5.5V
- Voltage - Load:
- 5V ~ 50V
- Operating Temperature:
- -20°C ~ 150°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Through Hole
- Supplier Device Package:
- 16-DIP
A4975SB-T FAQ
1.How can I place an order for A4975SB-T through Aetrix?
Please submit a Request for Quotation (RFQ) for A4975SB-T on Aetrix. Our sales agent will provide a competitive quotation and guide you through the order confirmation once you accept the terms.
2.Are the price and stock information for A4975SB-T reliable?
The price and inventory of A4975SB-T are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for A4975SB-T is usually 5 days.
3.What payment methods are accepted for A4975SB-T?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for A4975SB-T transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for A4975SB-T?
A4975SB-T orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your A4975SB-T order is processed, you will receive an email with the shipment details and tracking number.
Note: Tracking information may take up to 24 hours to appear. Express delivery typically takes 3–5 business days.
5.How can I obtain technical support or documentation for A4975SB-T?
For technical support, including A4975SB-T datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your A4975SB-T requirements.
6.How does Aetrix verify that A4975SB-T is sourced from the original manufacturer or authorized distributors?
All A4975SB-T products on Aetrix are procured from qualified distributors and authorized channels. Our dedicated quality assurance team conducts strict verification, including traceability checks and, if necessary, third-party testing. This ensures that A4975SB-T meets industry standards.
7.What is the process for return or replacement of A4975SB-T?
All A4975SB-T units undergo pre-shipment inspection (PSI). If there is an issue with A4975SB-T, returns or replacements are accepted under the following conditions:
1.Quantity discrepancies, incorrect items, or visible external defects (such as breakage or corrosion), acknowledged by Aetrix.
2.The issue is reported within 90 days of delivery.
3.The A4975SB-T part is unused and in its original packaging.
Return procedure for A4975SB-T:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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