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Allegro MicroSystems A3959SB
- Part No.:
- A3959SB
- Manufacturer:
- Allegro MicroSystems
- Category:
- Motor Drivers, Controllers
- Package:
- 24-PowerDIP (0.300", 7.62mm)
- Datasheet:
-
A3959SB.pdf
- Description:
- IC MOTOR DRIVER 4.5V-5.5V 24DIP
- Quantity:
- Payment:
- Shipping:
Inventory:1,959
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Product details
Overview
A3959SB from Allegro MicroSystems is a DMOS full-bridge PWM motor driver IC designed for bidirectional DC motor control with ±3 A output current and 50 V load supply capability. It implements internal fixed off-time current regulation, synchronous rectification, and selectable slow/fast/mixed current-decay modes via PFD1/PFD2 inputs. Used in precision speed and direction control of brushed DC motors in industrial actuators and automated equipment.
For engineers reviewing the A3959SB datasheet, A3959SB pinout, A3959SB application, or A3959SB equivalent, key selection criteria include thermal performance (RθJA = 40°C/W for LP package), integrated charge pump and VREG regulation, external ROSC-based oscillator tuning, and fault protection including thermal shutdown (165°C) and UVLO (4.2 V).
Technical Context
The A3959SB integrates dual DMOS H-bridge drivers with independent source/sink gate drive, an internal 4.25 MHz oscillator (adjustable via ROSC resistor), and a 10× reference divider for current sensing. Its current regulation uses VREF/10RS to set ITRIP, with blanking timed by BLANK input and oscillator frequency.
It supports three decay modes via PFD1/PFD2 logic: slow (both sinks on), fast (opposite pair active), and mixed (15% or 48% fast then slow). Synchronous rectification replaces body diode conduction during decay, reducing power loss by enabling low-rDS(on) (270 mΩ typ.) MOSFETs as freewheeling paths.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Current Rating | ±3.0 A continuous - defines maximum bidirectional motor winding current under thermal limits |
| Load Supply Voltage | 9.5–50 V - supports wide-range DC motor supplies including 12 V, 24 V, and 48 V systems |
| rDS(on) (Typ.) | 270 mΩ per channel - determines conduction loss and junction temperature rise at rated current |
| Fixed Off-Time | 24 µs typical - sets minimum current decay duration and maximum PWM frequency (~42 kHz) |
| Thermal Shutdown Threshold | 165°C with 15°C hysteresis - protects against sustained overload or poor heatsinking |
| VDD Operating Range | 4.5–5.5 V - requires stable 5 V logic supply; UVLO activates below 4.2 V |
| Oscillator Frequency Range | 3.25–5.25 MHz - adjustable via ROSC (20–100 kΩ) to tune PWM timing and decay resolution |
Pinout & Package
The A3959SB is supplied in the 28-pin TSSOP package (suffix 'LP') with exposed thermal pad, optimized for high-power density and thermal performance (RθJP = 2°C/W). All ground pins (7, 8, 28) must be connected together at the exposed pad.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| OUTA / OUTB | H-bridge output terminals | Drive motor winding ends; configured as source/sink pair based on PHASE/ENABLE state |
| VBB | Load supply input | High-current (≤50 V) motor power rail; requires ≥47 µF local electrolytic decoupling |
| VDD | Logic supply input | 5 V digital supply for control logic; monitored for UVLO (4.2 V threshold) |
| SENSE | Current sense input | Connects to low-side sense resistor; enables ITRIP = VREF/10RS current regulation |
| REF | Reference voltage input | Analog input (0–VDD) setting trip point; internally divided by 10 for comparator |
| PHASE | Direction control input | Logic level selects forward/reverse motor rotation (OUTA/OUTB polarity swap) |
| ENABLE | PWM enable input | High enables selected output pair; chopping ENABLE provides external current control |
| EXT MODE | Decay mode selector | High = slow decay, Low = fast decay; used with PFD1/PFD2 for mixed decay |
| PFD1 / PFD2 | Fast-decay configuration | Set 0%/15%/48%/100% fast-decay portion of fixed off-time period |
| BLANK | Comparator blanking control | Extends blank time to 6/fOSC or 12/fOSC to suppress switching transients |
| ROSC | Oscillator timing resistor | Resistor to VDD sets internal PWM timer frequency (e.g., 51 kΩ → 4.25 MHz) |
| CP / CP1 / CP2 | Charge pump network | Generates >VBB gate drive for high-side DMOS; requires 0.22 µF ceramic caps |
| VREG | Internal regulator output | Supplies sink-side gate drive; requires 0.22 µF decoupling capacitor to ground |
| SLEEP | Low-power mode control | Logic low disables charge pump, regulator, and drivers to reduce quiescent current to 20 µA |
Key Features
| Feature | Design Value |
|---|---|
| Synchronous rectification | Replaces lossy body diodes with active low-rDS(on) MOSFET conduction during decay, cutting power dissipation by >40% vs. asynchronous operation |
| Mixed current-decay mode | Combines fast decay (for rapid current reduction) and slow decay (for smooth torque delivery) within one off-time cycle, minimizing audible noise and torque ripple |
| Integrated charge pump & VREG | Eliminates need for external high-voltage gate drivers or dual supplies-enables full H-bridge operation from single 50 V rail |
| Programmable PWM oscillator | ROSC resistor allows precise tuning of off-time and blanking intervals to match motor inductance and system EMI requirements |
| Comprehensive fault protection | Thermal shutdown (165°C), UVLO (4.2 V), charge pump/VREG monitoring, and crossover-current protection prevent latch-up and destructive failure |
Applications
| Industrial Linear Actuators | Automated Door Operators |
|---|---|
Use Scenario: Precise position and force control of lead-screw or belt-driven linear motion systems in factory automation. IC Role / Device Role / Timing Role: Full-bridge motor driver executing bidirectional PWM current control with real-time decay-mode adaptation to load inertia. Use Value: Enables smooth acceleration/deceleration without torque spikes, supported by mixed-decay mode and 24 µs fixed off-time resolution. |
Use Scenario: Reliable open/close sequencing of heavy commercial doors with soft-start and emergency stop compliance. IC Role / Device Role / Timing Role: Motor controller implementing braking via slow-decay mode and ENABLE chop, independent of current-sense feedback. Use Value: Delivers controlled BEMF short-circuit braking without exceeding ±3 A output rating, avoiding external brake FETs. |
| Medical Infusion Pumps | Robotic Joint Actuation |
Use Scenario: Low-noise, microstepped peristaltic or stepper-motor-replacement pumping in portable infusion devices. IC Role / Device Role / Timing Role: Precision current-regulated driver using VREF/10RS sensing and synchronous rectification to minimize heat in sealed enclosures. Use Value: Achieves <±5% current accuracy over temperature, critical for dosage consistency, with thermal shutdown (165°C) ensuring safety margin. |
Use Scenario: Compact, high-torque joint drives in collaborative robots requiring dynamic response and thermal resilience. IC Role / Device Role / Timing Role: High-efficiency H-bridge managing bidirectional torque with fast transient recovery via 270 mΩ rDS(on) and 40°C/W thermal resistance. Use Value: Supports 50 V supply headroom for back-EMF suppression during rapid direction reversal, reducing external snubber complexity. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar full-bridge PWM motor driver applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| TB9051FTG | Integrated current sense amplifier and SPI interface; higher VBB max (40 V); no external ROSC tuning | Targets automotive body control modules requiring diagnostics and CAN communication | Choose when system-level diagnostics, functional safety reporting, or lower voltage (≤40 V) operation are required |
| DRV8876N | Higher output current (±6.5 A); integrated current regulation with internal sense; no charge pump (requires dual supply) | Optimized for compact battery-powered tools needing peak current burst capability | Choose when higher peak current, smaller PCB area, or elimination of external sense resistor are priorities |
Compared with TB9051FTG and DRV8876N, the A3959SB offers unique flexibility in decay-mode configuration, programmable oscillator timing, and single-supply operation up to 50 V-making it optimal for industrial motion systems where thermal management, EMI control, and analog current-loop fidelity are critical.
Availability
A3959SB is available at Aetrix Electronics and suitable for industrial motion control, automated access systems, and medical fluid delivery requiring stable component supply, long-term lifecycle support, and traceable sourcing.
Supply support for A3959SB 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 of high-performance magnetic sensors and power ICs, specializing in motion control and energy-efficient semiconductor solutions.
The A3959SB belongs to Allegro's DMOS full-bridge motor driver product line, engineered for robust, thermally efficient brushed DC motor control in demanding industrial and medical environments.
FAQ
What is the maximum continuous output current supported by the A3959SB?
The A3959SB supports ±3.0 A continuous output current under specified thermal conditions (e.g., 2-layer PCB with 1-in² copper, RθJA = 40°C/W). Peak current up to ±6.0 A is allowed for pulses shorter than 3 µs. Actual current capability depends on ambient temperature, PCB copper area, and heatsinking-exceeding 150°C junction temperature will trigger thermal shutdown.
How does the A3959SB implement current regulation without an external op-amp?
The A3959SB uses an internal fixed off-time PWM controller that compares the voltage across an external sense resistor (connected to SENSE) with a scaled version of VREF (divided by 10). When the sensed voltage reaches VREF/10, the source driver turns off for a fixed 24 µs period. This closed-loop method eliminates need for external amplifiers while maintaining ±4% Gm error across VREF range.
Can the A3959SB operate from a single 24 V supply, or does it require separate logic and motor rails?
Yes, the A3959SB operates from a single 24 V supply for both motor (VBB) and logic (VDD) domains. Its integrated charge pump generates boosted gate drive for high-side DMOS, and VREG provides regulated sink-side drive-all from VBB. VDD must still be supplied separately at 4.5–5.5 V, but this can be derived locally from VBB using a simple LDO or DC-DC converter.
What is the role of the BLANK input on the A3959SB, and how should it be configured?
The BLANK input on the A3959SB controls duration of the current-sense comparator blanking window after source-driver turn-on, preventing false trip from switching transients. With BLANK = 0, blank time = 6/fOSC (~1.4 µs at 4.25 MHz); with BLANK = 1, it doubles to 12/fOSC. Connect BLANK to GND or VDD depending on observed noise margin-do not leave floating.
Does the A3959SB support regenerative braking, and how is it implemented?
The A3959SB does not support true regenerative braking (energy return to supply), but implements effective dynamic braking via slow-decay mode and ENABLE chopping. In this mode, both sink outputs conduct during off-time, shorting the motor terminals and dissipating kinetic energy as heat in the windings and MOSFETs-no current flows through the sense resistor, so internal regulation is inactive.
A3959SB Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Allegro MicroSystems
- Series:
- -
- Package/Case:
- 24-PowerDIP (0.300", 7.62mm)
- Packaging:
- Tube
- Product Status:
- Obsolete
- Motor Type - Stepper:
- -
- Motor Type - AC, DC:
- Brushed DC
- Function:
- Driver - Fully Integrated, Control and Power Stage
- Output Configuration:
- Half Bridge (2)
- Interface:
- Parallel
- Technology:
- DMOS
- Step Resolution:
- -
- Applications:
- General Purpose
- Current - Output:
- 3A
- Voltage - Supply:
- 4.5V ~ 5.5V
- Voltage - Load:
- 9.5V ~ 50V
- Operating Temperature:
- -20°C ~ 150°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Through Hole
- Supplier Device Package:
- 24-DIP
A3959SB FAQ
1.How can I place an order for A3959SB through Aetrix?
Please submit a Request for Quotation (RFQ) for A3959SB 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 A3959SB reliable?
The price and inventory of A3959SB are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for A3959SB is usually 5 days.
3.What payment methods are accepted for A3959SB?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for A3959SB transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for A3959SB?
A3959SB orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your A3959SB 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 A3959SB?
For technical support, including A3959SB datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your A3959SB requirements.
6.How does Aetrix verify that A3959SB is sourced from the original manufacturer or authorized distributors?
All A3959SB 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 A3959SB meets industry standards.
7.What is the process for return or replacement of A3959SB?
All A3959SB units undergo pre-shipment inspection (PSI). If there is an issue with A3959SB, 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 A3959SB part is unused and in its original packaging.
Return procedure for A3959SB:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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