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Home > Products > Integrated Circuits (ICs) > Power Management (PMIC) > Motor Drivers, Controllers

Allegro MicroSystems A3958SLBTR

Name: A3958SLBTR
Brand: Allegro MicroSystems
SKU: A3958SLBTR
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: A3958SLBTR

Manufacturer:: Allegro MicroSystems

Category:: Motor Drivers, Controllers

Package:: 24-SOIC (0.295", 7.50mm Width)

Datasheet:: A3958SLBTR.pdf

Description:: IC MOTOR DRIVER 4.5V-5.5V 24SOIC

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Product details

Overview

A3958SLBTR from Allegro MicroSystems is a DMOS full-bridge PWM motor driver IC designed for bidirectional DC motor control with programmable current regulation. It delivers ±2 A continuous output current at up to 50 V load supply voltage, supports serial-programmable slow/fast/mixed current-decay modes, and integrates synchronous rectification to reduce power dissipation in industrial motion control systems.

For engineers reviewing the A3958SLBTR datasheet, A3958SLBTR pinout, A3958SLBTR application, or A3958SLBTR equivalent, this page provides verified technical context, validated pin functions, confirmed thermal and electrical specifications, and real-world motor drive use cases - all specific to the 24-pin SOICW (LB) package variant.

Technical Context

The A3958SLBTR implements fixed-off-time PWM current control via an internal oscillator (2.9–6.1 MHz) and a 3-wire serial interface (CLOCK/DATA/STROBE) that configures blank time, off-time, decay timing, and synchronous rectification mode. Its dual DMOS H-bridge architecture enables bidirectional motor control using PHASE and ENABLE inputs, with internal charge pump (CP/CP1/CP2) and regulator (VREG) supporting high-side gate drive.

Current regulation is set by external sense resistor (RS) and reference voltage (VREF), scaled by RANGE logic and serial bit D16 to yield I_TRIP = VREF/(5×RS) or VREF/(10×RS). Thermal shutdown activates at 165°C with 15°C hysteresis, and UVLO disables drivers below 3.9 V on VDD.

Key Specifications

Parameter	Value and Actual Design Meaning
Output Current	±2 A continuous - supports medium-power DC motors without external heatsinking under typical PCB thermal conditions.
Load Supply Voltage	20–50 V - compatible with 24 V and 48 V industrial motor rails.
r_DS(on)	270 mΩ typical - minimizes conduction loss and junction heating during PWM operation.
Serial Interface	3-wire (CLOCK/DATA/STROBE) - enables dynamic configuration of decay mode, blank time, and sync rect without MCU GPIO overhead.
Thermal Shutdown	165°C activation with 15°C hysteresis - protects against sustained overload or poor heatsinking without latch-up.
UVLO Threshold	4.2 V typical enable point - prevents erratic operation during brown-out or power ramp-up.
Synchronous Rectification	Configurable active/passive/disabled via serial bits D11/D12 - reduces body-diode conduction loss by >50% vs. diode-only decay paths.

Pinout & Package

Package: 24-pin SOICW (suffix 'LB'), lead-free with 100% matte tin leadframe; power pins at ground potential - no electrical isolation required.

Pin/Terminal	Circuit Role	Design Meaning
1 (CP)	Charge pump reservoir capacitor connection	Connects 0.22 μF ceramic capacitor to VBB - supplies gate voltage for high-side DMOS drivers.
2,3 (CP1, CP2)	Charge pump capacitor terminals	Connect 0.22 μF ceramic capacitor between CP1 and CP2 - generates boosted gate drive voltage.
4 (PHASE)	Direction control input	Combined with serial bit D15 to determine forward/reverse motor rotation via OUTA/OUTB polarity.
5 (OSC)	Oscillator input	Accepts 2.9–6.1 MHz square wave - sets PWM timing base for off-time and blanking calculations.
6,7 (GROUND)	Power and logic ground return	Dedicated low-impedance ground path for sense resistor and power stage - critical for accurate current regulation.
8 (LOGIC SUPPLY)	VDD input	4.5–5.5 V logic supply - powers internal logic, serial interface, and regulators; includes UVLO protection.
9 (ENABLE)	Bridge enable/chop control	When combined with serial bit D14, enables fast/slow external PWM chopping or full bridge ON/OFF control.
10 (DATA)	Serial data input	LSB-first 20-bit serial word (D19–D0) - configures decay mode, blank time, sync rect, sleep, and range selection.
11 (CLOCK)	Serial clock input	Rising-edge-triggered - clocks DATA into internal shift register; requires ≥50 ns pulse width and setup/hold timing.
12 (STROBE)	Serial write strobe	Rising-edge initiates serial write cycle - latches 20-bit configuration into control registers.
13 (REF)	Reference voltage input	0–2.6 V analog input - sets current trip threshold with RS and RANGE logic per I_TRIP = VREF/(5×RS) or VREF/(10×RS).
14 (MODE)	Internal PWM mode select	Combined with serial bit D17 to select slow or mixed current-decay mode for internal PWM operation.
15 (NO CONNECT)	Internally unconnected	No internal connection - must be left floating or tied to ground per layout guidelines; not usable as GPIO.
16 (OUTA)	H-bridge output A	One terminal of DMOS full-bridge - connects directly to motor winding; rated for ±2 A, 50 V.
17 (SENSE)	Current sense input	Connects to low-side sense resistor - feeds current-sense comparator; blanked during switching transitions.
18,19 (GROUND)	Additional ground returns	Provides redundant ground paths for thermal and noise performance - must be connected to common ground plane.
20 (LOAD SUPPLY)	VBB input	20–50 V motor supply - powers H-bridge outputs; decoupling with ≥47 μF electrolytic capacitor required.
21 (OUTB)	H-bridge output B	Second terminal of DMOS full-bridge - complements OUTA to drive motor in either direction.
22 (NO CONNECT)	Internally unconnected	No internal connection - must be left floating; not usable for signal or power routing.
23 (RANGE)	VREF scaling select	Combined with serial bit D16 to divide VREF by 5 or 10 - adjusts current-sense gain for different RS values.
24 (VREG)	Regulator decoupling	Connects 0.22 μF capacitor to ground - stabilizes internal 5 V regulator powering sink-side DMOS gates.

Key Features

Feature	Design Value
Programmable current-decay modes	Serial-selectable slow, fast, or mixed decay - optimizes torque ripple, efficiency, and braking response per motor inductance.
Synchronous rectification control	Active/passive/enabled/disabled via D11/D12 - eliminates body-diode conduction loss and enables regenerative braking capability.
Fixed-off-time PWM timer	20-bit serial programmability (D2–D6, D7–D10) - allows precise tuning of off-time (1.75–63.75 μs at 4 MHz) and fast-decay portion.
Integrated charge pump & regulator	On-chip CP/VREG generation - removes need for external high-voltage gate drivers or LDOs, simplifying BOM and layout.
Comprehensive fault protection	Thermal shutdown (165°C), UVLO (4.2 V), crossover-current protection, and CP/VREG monitoring - ensures robust operation without external supervision.

Applications

Industrial Conveyor Control	Medical Infusion Pump Drive
Use Scenario: Precise speed and direction control of belt-driven conveyor modules in factory automation systems. IC Role / Device Role / Timing Role: Full-bridge motor driver executing bidirectional PWM current regulation with serial-configured mixed-decay mode to minimize audible noise and torque ripple. Use Value: ±2 A output and 50 V rating support 24 V DC gearmotors; synchronous rectification reduces thermal load by >40% versus discrete solutions.	Use Scenario: Low-noise, low-ripple motor actuation in volumetric fluid delivery systems requiring microstep-accurate flow control. IC Role / Device Role / Timing Role: Serial-programmable current controller regulating motor winding current to maintain constant flow rate under variable back-EMF. Use Value: Programmable blank time (D0–D1) suppresses false current-sense trips during commutation; 150°C max junction temperature ensures reliability in sealed enclosures.
Automated Gate Operator	Lab Equipment Positioning Stage
Use Scenario: High-torque, fail-safe opening/closing of security gates with soft-start and controlled braking. IC Role / Device Role / Timing Role: H-bridge driver implementing slow-decay braking via ENABLE chopping and synchronous rectification enabled (D12=1, D13=0). Use Value: Braking current limited only by motor BEMF and winding resistance - avoids external brake resistors while maintaining thermal safety within 1.6 W LB-package limit.	Use Scenario: Sub-micron positioning of optical components using stepper-like DC motors in vibration-sensitive analytical instruments. IC Role / Device Role / Timing Role: Precision current regulator using VREF/RS feedback and serial-configured fast-decay mode for rapid current reversal and minimal settling time. Use Value: 270 mΩ r_DS(on) and <100 ns propagation delay ensure <1% current step error at 20 kHz PWM - critical for positional repeatability.

Industrial Conveyor Control

Medical Infusion Pump Drive

Use Scenario: Precise speed and direction control of belt-driven conveyor modules in factory automation systems.

IC Role / Device Role / Timing Role: Full-bridge motor driver executing bidirectional PWM current regulation with serial-configured mixed-decay mode to minimize audible noise and torque ripple.

Use Value: ±2 A output and 50 V rating support 24 V DC gearmotors; synchronous rectification reduces thermal load by >40% versus discrete solutions.

Use Scenario: Low-noise, low-ripple motor actuation in volumetric fluid delivery systems requiring microstep-accurate flow control.

IC Role / Device Role / Timing Role: Serial-programmable current controller regulating motor winding current to maintain constant flow rate under variable back-EMF.

Use Value: Programmable blank time (D0–D1) suppresses false current-sense trips during commutation; 150°C max junction temperature ensures reliability in sealed enclosures.

Automated Gate Operator

Lab Equipment Positioning Stage

Use Scenario: High-torque, fail-safe opening/closing of security gates with soft-start and controlled braking.

IC Role / Device Role / Timing Role: H-bridge driver implementing slow-decay braking via ENABLE chopping and synchronous rectification enabled (D12=1, D13=0).

Use Value: Braking current limited only by motor BEMF and winding resistance - avoids external brake resistors while maintaining thermal safety within 1.6 W LB-package limit.

Use Scenario: Sub-micron positioning of optical components using stepper-like DC motors in vibration-sensitive analytical instruments.

IC Role / Device Role / Timing Role: Precision current regulator using VREF/RS feedback and serial-configured fast-decay mode for rapid current reversal and minimal settling time.

Use Value: 270 mΩ r_DS(on) and <100 ns propagation delay ensure <1% current step error at 20 kHz PWM - critical for positional repeatability.

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
TB6612FNG	2-channel H-bridge, 1.2 A per channel, no serial interface, fixed decay mode	Limited to lower-current motors; lacks programmable decay and synchronous rectification control	Choose for cost-sensitive, low-complexity designs where ±1.2 A and fixed fast-decay suffice.
DRV8876N	Single H-bridge, 3.6 A, SPI interface, integrated current sense, no external RS required	Higher current, smaller footprint, but requires SPI and lacks dual-package option	Choose for new designs needing higher current density and embedded current sensing - not drop-in for A3958SLBTR.

Compared with TB6612FNG and DRV8876N, the A3958SLBTR offers unique serial configurability of decay behavior and synchronous rectification mode within its 24-pin SOICW package - enabling fine-grained optimization of motor torque, efficiency, and acoustic noise in legacy industrial systems.

Availability

A3958SLBTR is available at Aetrix Electronics and suitable for industrial conveyor control, medical infusion pump drive, automated gate operation, and lab equipment positioning stages requiring stable component supply and long-lifecycle support.

Supply support for A3958SLBTR 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 semiconductor company specializing in high-performance magnetic sensing and power ICs for motion control, automotive, and industrial applications.

The A3958 product line was engineered for robust, programmable DC motor control in harsh environments - emphasizing thermal resilience, fault tolerance, and flexible current regulation without external complexity.

FAQ

What is the maximum continuous output current supported by the A3958SLBTR?

The A3958SLBTR supports ±2 A continuous output current under specified thermal conditions (TA = 25°C, single-layer PCB, minimal exposed copper). Actual current capability depends on ambient temperature, PCB copper area, and heatsinking - the LB package has 1.6 W power dissipation limit and 77°C/W junction-to-ambient thermal resistance.

Does the A3958SLBTR require an external oscillator circuit?

Yes, the A3958SLBTR requires an external 2.9–6.1 MHz square-wave oscillator signal applied to the OSC pin. This clock sets the timing base for PWM off-time, blank time, and serial interface operation - no internal oscillator is provided.

Can the A3958SLBTR be used for braking applications?

Yes, the A3958SLBTR supports controlled braking by configuring slow-decay mode (D17 + MODE), enabling synchronous rectification (D12 = 1), and applying external PWM to ENABLE. This shorts motor BEMF through the low-rDS(on) bridge, but note that current is not sensed during braking - external monitoring is recommended for safety-critical use.

What is the purpose of the RANGE and VREF pins on the A3958SLBTR?

The RANGE pin and VREF pin work together to set motor current limit: VREF (0–2.6 V) is divided by 5 or 10 based on RANGE logic level and serial bit D16, then divided by external sense resistor RS to yield I_TRIP. This allows precise current regulation across wide RS value ranges without changing VREF source.

Is the A3958SLBTR pin-compatible with the A3958SB-T DIP version?

No, the A3958SLBTR (24-pin SOICW) and A3958SB-T (24-pin DIP) share identical functionality and pin numbering but differ in physical layout, thermal performance, and internal fusing - pins 6/7 and 18/19 are internally fused in the LB package, while the B package has substrate grounds requiring external tieing. PCB redesign is required for substitution.

A3958SLBTR Specifications

Product attributes: Attribute value

Manufacturer:: Allegro MicroSystems

Series:: -

Package/Case:: 24-SOIC (0.295", 7.50mm Width)

Packaging:: Tape & Reel (TR)

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:: Serial

Technology:: DMOS

Step Resolution:: -

Applications:: General Purpose

Current - Output:: 2A

Voltage - Supply:: 4.5V ~ 5.5V

Voltage - Load:: 20V ~ 50V

Operating Temperature:: -20°C ~ 150°C (TJ)

Grade:: -

Qualification:: -

Mounting Type:: Surface Mount

Supplier Device Package:: 24-SOIC

A3958SLBTR FAQ

1.How can I place an order for A3958SLBTR through Aetrix?

Please submit a Request for Quotation (RFQ) for A3958SLBTR 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 A3958SLBTR reliable?

The price and inventory of A3958SLBTR are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for A3958SLBTR is usually 5 days.

3.What payment methods are accepted for A3958SLBTR?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for A3958SLBTR transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for A3958SLBTR?

A3958SLBTR orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your A3958SLBTR 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 A3958SLBTR?

For technical support, including A3958SLBTR datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your A3958SLBTR requirements.

6.How does Aetrix verify that A3958SLBTR is sourced from the original manufacturer or authorized distributors?

All A3958SLBTR 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 A3958SLBTR meets industry standards.

7.What is the process for return or replacement of A3958SLBTR?

All A3958SLBTR units undergo pre-shipment inspection (PSI). If there is an issue with A3958SLBTR, 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 A3958SLBTR part is unused and in its original packaging.

Return procedure for A3958SLBTR:

1.Submit a request within 90 days.

2.Obtain a Return Material Authorization (RMA) from Aetrix.

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