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Allegro MicroSystems A3953SLBTR-T
- Part No.:
- A3953SLBTR-T
- Manufacturer:
- Allegro MicroSystems
- Category:
- Motor Drivers, Controllers
- Package:
- 16-PowerSOIC (0.295", 7.50mm Width)
- Datasheet:
-
A3953SLBTR-T.pdf
- Description:
- IC MTR DRV BIPOLAR 3-5.5V 16SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:2,421
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Product details
Overview
A3953SLBTR-T from Allegro MicroSystems is a discontinued 16-pin SOICW full-bridge PWM motor driver IC designed for bidirectional current control of brushed DC and stepper motors. It delivers ±1.3 A continuous output current at up to 50 V load supply, features internal fixed off-time PWM current regulation, thermal shutdown with 8°C hysteresis, and supports fast/slow current-decay modes via MODE pin - used in industrial motion control and automotive HVAC actuators.
For engineers reviewing the A3953SLBTR-T datasheet, A3953SLBTR-T pinout, A3953SLBTR-T application, or A3953SLBTR-T equivalent, key selection considerations include its SOICW package with internally fused pins, RC-timed off-time configuration (tOFF ≈ RT × CT), brake-mode override behavior, and discontinuation status requiring legacy design support or migration planning.
Technical Context
The A3953SLBTR-T implements a fixed off-time PWM current-control architecture using an external RC network on the RC pin to set tOFF (18.3–22.5 μs typical with 30 kΩ/680 pF). Its internal latch-based comparator monitors voltage across an external sense resistor (RS) against a user-set reference (REF) to regulate peak current (ITRIP ≈ VREF/RS – ISO).
It operates in three functional states: forward/reverse (PHASE-controlled polarity), brake (BRAKE = L overrides ENABLE/PHASE), and sleep (ENABLE = MODE = BRAKE = H). Crossover dead time (0.3–3.0 μs) prevents shoot-through, while blanking during PHASE/ENABLE transitions suppresses false trips from clamp diode reverse recovery.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Continuous Output Current | ±1.3 A - supports medium-power brushed DC motors (e.g., 24 V, 15 W) without external heatsinking under defined thermal conditions. |
| Load Supply Voltage | 5 V to 50 V - compatible with 12 V/24 V/48 V industrial and automotive battery systems. |
| Logic Supply Voltage | 3.0 V to 5.5 V - interfaces directly with 3.3 V or 5 V microcontrollers without level shifting. |
| PWM Fixed Off-Time | 18.3–22.5 μs (typ.) - sets minimum current decay interval; adjustable via external RT/CT to optimize EMI, ripple, and low-current regulation. |
| Thermal Shutdown Threshold | 165°C (typ.) with 8°C hysteresis - protects against sustained overload or poor PCB thermal design; recovery requires junction cooling below ~157°C. |
| Maximum PWM Frequency | 70 kHz - enables high-speed current loop control while maintaining sufficient tON(min) margin for stable regulation. |
| UVLO Threshold | 2.5–3.0 V - prevents erratic operation during brown-out; ensures clean enable/disable sequencing when VCC ramps. |
Pinout & Package
Package: 16-pin SOICW (wide-body) with internally fused pins and exposed thermal tab at ground potential - requires no electrical isolation; optimized for surface-mount assembly and moderate power dissipation (RθJA = 67°C/W on 2-layer PCB with 0.3 in² copper).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1, 2, 3, 4, 5, 6, 7, 8, 12, 13, 14, 15 | Ground (GND) | Multiple GND pins provide low-impedance return paths for logic, sense, and power grounds - critical for noise immunity and accurate current sensing. |
| 9 | VBB | Motor supply input (5–50 V); must be decoupled with ≥47 μF electrolytic capacitor placed adjacent to pin to suppress switching transients. |
| 10 | RC | RC timing node - connects external RT/CT to set fixed off-time; also controls comparator blanking window duration. |
| 11 | REF | Reference voltage input - sets peak current limit (ITRIP) with external sense resistor; max bias current ±5 μA. |
| 16 | VCC | Logic supply (3.0–5.5 V); powers internal logic, comparators, and gate drivers - separate from VBB for noise isolation. |
| OUTA / OUTB (pins 11 & 12 per functional diagram) | H-bridge outputs | Drive motor terminals; each capable of ±1.3 A; integrated clamp diodes handle inductive flyback energy. |
Key Features
| Feature | Design Value |
|---|---|
| Internal PWM current control | Eliminates need for external current-sense amplifier and PWM controller - reduces BOM count and layout complexity in closed-loop motor drives. |
| Fast/slow current-decay mode selection | MODE pin configures decay path: slow decay (source off only) minimizes switching loss in microstepping; fast decay (source + sink off) improves current settling in servo applications. |
| Brake function with override priority | BRAKE = L forces both sinks ON and both sources OFF - enables dynamic braking independent of ENABLE/PHASE state, critical for emergency stop or position holding. |
| Integrated protection circuitry | Combines thermal shutdown (165°C), UVLO, crossover current prevention, and internal clamp diodes - eliminates need for discrete protection components in most 24 V industrial designs. |
| Sleep mode with ultra-low quiescent current | ICC(Sleep) = 500–800 μA - enables energy-efficient standby in battery-powered actuators without external power gating. |
Applications
| Industrial Valve Actuators | Automotive HVAC Blower Control |
|---|---|
|
Use Scenario: Precise bidirectional positioning of linear solenoid valves in pneumatic control systems. IC Role / Device Role / Timing Role: Full-bridge driver regulating coil current via internal PWM to achieve sub-millisecond step response and hold torque without overheating. Use Value: ±1.3 A capability and slow-decay mode reduce iron losses in solenoid coils, extending actuator life and enabling silent operation in factory automation environments. |
Use Scenario: Speed and direction control of 24 V DC blower motors in vehicle climate control modules. IC Role / Device Role / Timing Role: Motor driver executing PHASE PWM for smooth speed ramping and BRAKE for rapid airflow cutoff during mode changes. Use Value: Integrated clamp diodes and thermal shutdown ensure reliability under automotive load dump (ISO 7637-2) and ambient temperatures up to 85°C. |
| Stepper Motor Microstepping Drivers | Robotic Joint Actuators |
|
Use Scenario: Two-phase bipolar stepper motor control in CNC accessories and lab automation stages. IC Role / Device Role / Timing Role: Dual A3953SLBTR-T devices per motor phase implementing synchronized slow/fast decay based on current slope detection. Use Value: RC-timed off-time and blanking window prevent false current-limit trips during microstep transitions, enabling stable 1/8–1/16 stepping at 200–500 Hz. |
Use Scenario: Torque-controlled joint actuation in collaborative robots using brushed DC motors with current feedback. IC Role / Device Role / Timing Role: Current-regulated H-bridge providing precise torque output via REF voltage modulation and real-time current monitoring at SENSE pin. Use Value: ±1.3 A continuous rating and 50 V VBB headroom support high-inertia loads; sleep mode reduces standby power in idle joints. |
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 |
|---|---|---|---|
| A4973KLPTR-T | Successor device with higher 2.5 A continuous current, integrated current sense amplifier, and SPI interface; same 16-pin SOICW package but different pinout and RC timing architecture. | Supports closed-loop torque control without external op-amp; requires firmware update for SPI register access and new RC network design. | Select for new designs requiring higher current or digital configurability; not pin-compatible - PCB redesign required. |
| TB9051FTG | Automotive-grade 3.5 A full-bridge with built-in pre-driver, watchdog timer, and CAN-compatible diagnostics; 32-pin HTSSOP package with different thermal pad layout. | Meets ASIL-B requirements; includes fault reporting via dedicated FLAG pin and enhanced ESD/EMC robustness for chassis-mounted modules. | Select for automotive production programs needing functional safety compliance; requires full mechanical and schematic revision. |
Compared with A3953SLBTR-T, the A4973KLPTR-T offers higher current and digital control but demands layout changes, while the TB9051FTG adds safety features and diagnostic capability at the cost of increased package size and system integration complexity - both require validation against legacy thermal and EMI performance benchmarks.
Availability
A3953SLBTR-T is available at Aetrix Electronics and suitable for industrial valve actuation, automotive HVAC control, stepper motor microstepping, and robotic joint actuation requiring stable component supply for legacy system maintenance and repair.
Supply support for A3953SLBTR-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 of high-performance magnetic sensing and power ICs, specializing in motion control, current sensing, and motor driver solutions for automotive and industrial markets.
The A3953 product line was engineered for cost-sensitive, thermally constrained full-bridge motor control applications - emphasizing integrated protection, flexible decay mode selection, and RC-timed current regulation without external controllers.
FAQ
Is the A3953SLBTR-T still in production?
No, the A3953SLBTR-T is a discontinued product. Allegro MicroSystems ceased production effective January 30, 2012. It is not recommended for new designs, and samples are no longer available. Aetrix Electronics maintains limited legacy stock for repair and maintenance of existing equipment, with full traceability and documentation support.
What is the correct replacement for the A3953SLBTR-T in new designs?
The officially recommended replacement is the A4973KLPTR-T, which Allegro specifies for both new customer designs and existing customer transition. It provides higher current (2.5 A), integrated current sense amplification, and SPI programmability - though it requires PCB layout changes due to non-pin-compatible pinout and revised RC timing implementation.
Can the A3953SLBTR-T operate with a 3.3 V logic supply?
Yes, the A3953SLBTR-T supports VCC from 3.0 V to 5.5 V. At 3.3 V, the maximum allowable VSENSE is 0.4 V, and the RC timing network must use CT ≥ 680 pF ±5% to ensure sufficient comparator blanking time and stable PWM regulation.
How does the brake function interact with the ENABLE and PHASE inputs on the A3953SLBTR-T?
When BRAKE is pulled low, it overrides both ENABLE and PHASE: both source drivers turn off and both sink drivers turn on, forcing motor terminals to ground. This occurs regardless of ENABLE or PHASE state - enabling immediate dynamic braking even during active PWM control or sleep mode entry.
What thermal design guidance applies to the A3953SLBTR-T in SOICW package?
The A3953SLBTR-T in LB package has RθJA = 67°C/W on a 2-layer PCB with 0.3 in² exposed copper per side. To maintain TJ < 125°C at ±1.3 A, limit average power dissipation to ≤1.5 W using adequate copper pour on the thermal tab, avoid socketing, and consider adding external Schottky diodes in fast-decay applications to reduce junction temperature rise.
A3953SLBTR-T Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Allegro MicroSystems
- Series:
- -
- Package/Case:
- 16-PowerSOIC (0.295", 7.50mm Width)
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Obsolete
- Motor Type - Stepper:
- Bipolar
- Motor Type - AC, DC:
- Brushed DC
- Function:
- Driver - Fully Integrated, Control and Power Stage
- Output Configuration:
- Half Bridge (2)
- Interface:
- Parallel
- Technology:
- Bipolar
- Step Resolution:
- -
- Applications:
- General Purpose
- Current - Output:
- 1.3A
- Voltage - Supply:
- 3V ~ 5.5V
- Voltage - Load:
- 3V ~ 50V
- Operating Temperature:
- -20°C ~ 150°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 16-SOIC
A3953SLBTR-T FAQ
1.How can I place an order for A3953SLBTR-T through Aetrix?
Please submit a Request for Quotation (RFQ) for A3953SLBTR-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 A3953SLBTR-T reliable?
The price and inventory of A3953SLBTR-T are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for A3953SLBTR-T is usually 5 days.
3.What payment methods are accepted for A3953SLBTR-T?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for A3953SLBTR-T transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for A3953SLBTR-T?
A3953SLBTR-T orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your A3953SLBTR-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 A3953SLBTR-T?
For technical support, including A3953SLBTR-T datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your A3953SLBTR-T requirements.
6.How does Aetrix verify that A3953SLBTR-T is sourced from the original manufacturer or authorized distributors?
All A3953SLBTR-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 A3953SLBTR-T meets industry standards.
7.What is the process for return or replacement of A3953SLBTR-T?
All A3953SLBTR-T units undergo pre-shipment inspection (PSI). If there is an issue with A3953SLBTR-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 A3953SLBTR-T part is unused and in its original packaging.
Return procedure for A3953SLBTR-T:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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