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Allegro MicroSystems A3953SLB-T
- Part No.:
- A3953SLB-T
- Manufacturer:
- Allegro MicroSystems
- Category:
- Motor Drivers, Controllers
- Package:
- 16-PowerSOIC (0.295", 7.50mm Width)
- Datasheet:
-
A3953SLB-T.pdf
- Description:
- IC MTR DRV BIPOLAR 3-5.5V 16SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:2,181
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Product details
Overview
A3953SLB-T from Allegro MicroSystems is a discontinued 16-pin SOIC 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 input - used in industrial motion control and automotive HVAC actuators.
For engineers reviewing the A3953SLB-T datasheet, A3953SLB-T pinout, A3953SLB-T application, or A3953SLB-T equivalent, key selection considerations include its SOIC-LB package with 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 A3953SLB-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 at 3.3 V), while peak current ITRIP is set by VREF and sense resistor RS. Its internal latch-based control enables precise current limiting during forward/reverse operation and brake mode.
It integrates crossover current protection, UVLO (2.5–3.0 V enable threshold), and sleep mode (≤800 μA ICC) activated by high ENABLE/MODE/BRAKE. The device uses saturated sink drivers below 1 A and includes internal transient-suppression diodes - eliminating need for external flyback components in many low-power applications.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Continuous Output Current | ±1.3 A - supports medium-power brushed DC motors and 2-phase stepper windings 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 - interoperable with 3.3 V and 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 network for ripple/noise optimization. |
| Thermal Shutdown Threshold | 165°C (typ.) with 8°C hysteresis - protects against sustained overloads; recovery requires junction cooling below 157°C. |
| UVLO Enable Threshold | 2.5–3.0 V - prevents erratic operation during power-up/down; ensures stable logic interface before enabling outputs. |
| Maximum PWM Frequency | 70 kHz - limits switching losses while supporting responsive current regulation in servo loops. |
Pinout & Package
Package: 16-pin SOICW (LB suffix) 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).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1, 2, 3, 4, 5, 6, 7, 12, 13, 14, 15, 16 | Ground / Power Tab Connection | All labeled GND pins and exposed tab connect to system ground - provides low-impedance return path and thermal conduction to PCB copper. |
| 8 | RC Timing Input | Accepts external RT/CT network to set fixed off-time; also controls comparator blanking window duration. |
| 9 | VBB Load Supply | High-side power input (5–50 V); connects directly to motor supply rail and bulk decoupling capacitor (>47 μF). |
| 10 | SENSE Current Sense Input | Differential input monitoring voltage across external sense resistor RS; accepts 0–0.4 V (3.3 V logic) or 0–1.0 V (5 V logic). |
| 11 | REF Reference Input | Analog reference setting ITRIP = VREF/RS – ISO; max bias current ±5 μA - requires low-impedance source. |
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 motor drive stages. |
| Fast/slow current-decay mode selection | Enables optimization of torque ripple and efficiency: slow decay minimizes switching loss in hold/microstepping; fast decay improves dynamic response in servo positioning. |
| Brake function with override priority | Asserting BRAKE = low disables both source drivers and activates both sinks - delivers immediate dynamic braking independent of PHASE/ENABLE state. |
| Integrated transient-suppression diodes | Clamps inductive kickback during current decay - removes requirement for four external flyback diodes in most 24 V/1 A applications. |
| Sleep mode with ≤800 μA ICC | Reduces quiescent power in battery-powered systems during idle periods - enabled by high logic on ENABLE, MODE, and BRAKE simultaneously. |
Applications
| Industrial Actuator Control | Automotive HVAC Damper Drive |
|---|---|
|
Use Scenario: Precise bidirectional positioning of linear actuators in programmable logic controller (PLC)-based valve and damper systems. IC Role / Device Role / Timing Role: Full-bridge driver executing microcontroller-generated PHASE/ENABLE PWM commands while regulating winding current via internal PWM loop. Use Value: Enables closed-loop position control without external current-sense amplifiers or discrete MOSFET gate drivers - reducing component count and board area by ~30% vs discrete solutions. |
Use Scenario: Driving 12 V brushed DC motors controlling blend air doors in automotive climate control modules. IC Role / Device Role / Timing Role: Motor driver implementing brake-mode transitions during direction reversal to suppress mechanical backlash and reduce audible noise. Use Value: Internal brake function and fast/slow decay selection allow smooth, quiet actuation meeting OEM NVH requirements without added firmware complexity. |
| Stepper Motor Microstepping | Lab Equipment Motion Stage |
|
Use Scenario: Sinusoidal current profiling for 2-phase hybrid stepper motors in CNC accessories and 3D printer extruders. IC Role / Device Role / Timing Role: Dual-channel driver operating in slow-decay mode during current ramp-up and fast-decay mode during ramp-down to maintain waveform fidelity. Use Value: RC-timed off-time and blanking window prevent false overcurrent trips during high-frequency microstep transitions - sustaining >1/16-step resolution. |
Use Scenario: Low-noise, repeatable linear motion in optical alignment stages and spectrometer sample handlers. IC Role / Device Role / Timing Role: Precision current regulator maintaining ±1.3 A coil current with <5% ripple using internal PWM and external RS/VREF. Use Value: Thermal shutdown with hysteresis and UVLO ensure safe operation during extended unattended runs - critical for lab automation reliability. |
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 |
|---|---|---|---|
| A4973 | Successor device with improved thermal performance (RθJA = 40°C/W), higher 3 A continuous current rating, and integrated current-sense amplifier output. | Supports higher-power motors and eliminates need for external sense resistor feedback conditioning circuitry. | Recommended for new designs requiring higher current capability and simplified current monitoring. |
| MP6532 | Monolithic 2.8 A H-bridge with integrated MOSFETs, 4.5–35 V operation, and SPI-configurable decay modes - no external RC timing required. | Reduces external component count further but lacks analog REF/SENSE interface; requires digital configuration. | Suitable where board space is constrained and microcontroller has SPI interface available. |
Compared with A3953SLB-T, the A4973 offers higher current capacity and better thermal metrics for upgraded designs, while the MP6532 replaces discrete power stages with integrated FETs and digital control - shifting design focus from analog tuning to firmware configuration.
Availability
A3953SLB-T is available at Aetrix Electronics and suitable for legacy industrial motion control, automotive HVAC retrofit, and lab equipment repair requiring stable component supply despite end-of-life status.
Supply support for A3953SLB-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 developed for cost-sensitive, thermally constrained full-bridge motor drive applications requiring integrated protection and analog current regulation - targeting brushed DC and stepper motor control in harsh environments.
FAQ
Is the A3953SLB-T still in production?
No, the A3953SLB-T is a discontinued product. Allegro MicroSystems ceased production as of January 30, 2012. It is not recommended for new designs. Aetrix Electronics maintains limited legacy stock for repair and maintenance of existing systems, with full traceability and documentation support for the A3953SLB-T.
What is the difference between A3953SLB-T and A3953SB-T?
The A3953SLB-T uses a 16-pin SOICW package with internally fused pins and exposed thermal tab, while the A3953SB-T uses a 16-pin DIP package with copper heat-sink tabs. Both share identical electrical specifications and pin numbering, but the SLB-T is surface-mount compatible and has higher RθJA (67°C/W vs 43°C/W). The A3953SLB-T is the version referenced in this product page.
Can the A3953SLB-T be used in stepper motor applications?
Yes, the A3953SLB-T supports stepper motor drive via PHASE-controlled polarity switching and MODE-selectable fast/slow decay. It is commonly used in microstepping configurations where slow decay minimizes iron losses during current ramp-up and fast decay maintains profile accuracy during ramp-down - confirmed in Allegro's application notes for A3953SLB-T.
What does the RC pin do on the A3953SLB-T?
The RC pin on the A3953SLB-T sets the fixed off-time (tOFF) for the internal PWM current-control circuit via an external resistor-capacitor network (tOFF ≈ RT × CT). It also determines the comparator blanking window duration to suppress false overcurrent triggers caused by switching transients - a critical timing parameter validated in the A3953SLB-T datasheet.
Does the A3953SLB-T include built-in protection features?
Yes, the A3953SLB-T integrates thermal shutdown (165°C trip, 8°C hysteresis), UVLO (2.5–3.0 V), crossover current protection, and internal transient-suppression diodes. These protections are active across all operating modes including brake and sleep - verified in the Absolute Maximum Ratings and Electrical Characteristics sections of the official A3953SLB-T datasheet.
A3953SLB-T Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Allegro MicroSystems
- Series:
- -
- Package/Case:
- 16-PowerSOIC (0.295", 7.50mm Width)
- Packaging:
- Tube
- 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
A3953SLB-T FAQ
1.How can I place an order for A3953SLB-T through Aetrix?
Please submit a Request for Quotation (RFQ) for A3953SLB-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 A3953SLB-T reliable?
The price and inventory of A3953SLB-T are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for A3953SLB-T is usually 5 days.
3.What payment methods are accepted for A3953SLB-T?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for A3953SLB-T transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for A3953SLB-T?
A3953SLB-T orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your A3953SLB-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 A3953SLB-T?
For technical support, including A3953SLB-T datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your A3953SLB-T requirements.
6.How does Aetrix verify that A3953SLB-T is sourced from the original manufacturer or authorized distributors?
All A3953SLB-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 A3953SLB-T meets industry standards.
7.What is the process for return or replacement of A3953SLB-T?
All A3953SLB-T units undergo pre-shipment inspection (PSI). If there is an issue with A3953SLB-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 A3953SLB-T part is unused and in its original packaging.
Return procedure for A3953SLB-T:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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