My Inquiry
My Account
Allegro MicroSystems A3948SB
- Part No.:
- A3948SB
- Manufacturer:
- Allegro MicroSystems
- Category:
- Motor Drivers, Controllers
- Package:
- 24-PowerDIP (0.300", 7.62mm)
- Datasheet:
-
A3948SB.pdf
- Description:
- IC MOTOR DRIVER 4.5V-5.5V 24DIP
- Quantity:
- Payment:
- Shipping:
Inventory:4,557
Please send an inquiry. Send us your inquiry, and we will respond immediately.
Product details
Overview
A3948SB from Allegro MicroSystems is a discontinued 24-pin batwing DIP-packaged DMOS full-bridge PWM motor driver IC designed for bidirectional DC motor control with ±1.5 A continuous output current, 50 V load supply rating, and programmable mixed/fast/slow current-decay modes via 3-wire serial interface. It integrates synchronous rectification, thermal shutdown (165°C), and crossover-current protection for industrial motion control systems.
For engineers reviewing the A3948SB datasheet, A3948SB pinout, A3948SB application, or A3948SB equivalent, key selection considerations include its fixed-off-time PWM architecture, VBB/VDD dual-supply operation, ground-referenced power tab, serial-programmable decay timing, and compatibility with external sense-resistor-based current regulation up to 0.55 V sense voltage.
Technical Context
The A3948SB implements a fixed-off-time PWM current-control engine with oscillator input (1.8–6.1 MHz) and programmable blank time (4/fOSC to 24/fOSC) and off-time (1.75–63.75 µs at 4 MHz). Its serial port (CLOCK/DATA/STROBE) configures 20-bit control registers including D19 (Sleep), D17 (mixed/slow decay), D11/D12 (synchronous rectification mode/enable), and D16 (VREF range select).
It features dual-regulated internal supplies: VREG (for sink-side gate drive) and charge pump (CP/CP1/CP2) for source-side high-side drive, both monitored for fault shutdown. Thermal shutdown (165°C, 15°C hysteresis) and UVLO (4.2 V enable threshold) operate independently of serial configuration.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Current | ±1.5 A continuous - supports medium-power DC motors without external heatsinking under typical PCB copper area |
| Load Supply Voltage | 20–50 V - enables operation across 24 V and 48 V industrial motor rails |
| rDS(on) | 300–550 mΩ - sink/source on-resistance determines conduction loss and thermal rise at rated current |
| Junction Temp Limit | 150°C max - defines absolute thermal ceiling before permanent damage occurs |
| Thermal Resistance | RθJA = 40°C/W - specifies temperature rise per watt dissipated in standard 2-layer PCB layout |
| Sense Voltage Max | 0.55 V - sets maximum allowable voltage drop across external current-sense resistor RS |
| Oscillator Frequency | 1.8–6.1 MHz - directly scales PWM timing resolution and blank/off-time granularity |
Pinout & Package
Package: 24-pin plastic DIP with copper batwing tab (grounded); requires external decoupling: 0.22 µF on VREG, 0.22 µF between CP1–CP2, and 0.22 µF between CP–VBB.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1, 2 | CP1, CP2 | Charge pump capacitor terminals - form flying capacitor network to generate >VBB gate drive for high-side DMOS |
| 3 | PHASE | Direction control input - combined with serial bit D15 to determine forward/reverse motor state |
| 4 | OSC | Oscillator input - accepts square-wave clock (1.8–6.1 MHz) that defines all internal PWM timing |
| 5, 6, 7, 8* | GROUND | Substrate ground pins - must be externally shorted to pins 5 and 8; power tab is at ground potential |
| 9 | LOGIC SUPPLY (VDD) | 5 V logic rail - powers digital core; UVLO triggers at 4.2 V to prevent erratic operation |
| 10 | ENABLE | External PWM enable - controls bridge on/off state; programmable via serial bit D14 for fast/slow decay selection |
| 11 | DATA | Serial interface data input - LSB-first 20-bit register load synchronized to CLOCK rising edge |
| 12 | CLOCK | Serial interface clock - rising edge clocks DATA bits into internal shift register |
| 13 | STROBE | Serial write latch - rising edge transfers 20-bit register contents to control logic |
| 14 | REF (VREF) | Current reference input - sets ITRIP = VREF/(5RS) or VREF/(10RS) depending on RANGE and D16 |
| 15 | MODE | PWM mode select - combined with serial bit D17 to configure slow or mixed current-decay behavior |
| 16 | OUTA | H-bridge output A - one terminal of full-bridge connected to motor winding |
| 17 | SENSE | Current sense input - monitors voltage across external RS to trigger PWM current limiting |
| 18, 19* | GROUND | Additional substrate grounds - electrically tied to pins 5/6/7/8; require external common connection |
| 20 | LOAD SUPPLY (VBB) | High-voltage motor supply - 20–50 V input powering H-bridge outputs and charge pump reservoir |
| 21 | OUTB | H-bridge output B - second terminal of full-bridge; complements OUTA for bidirectional drive |
| 22 | RANGE | VREF divider select - combined with serial bit D16 to scale reference by ÷5 or ÷10 for ITRIP adjustment |
| 23 | VREG | Internal regulator output - supplies sink-side gate drive; requires 0.22 µF decoupling to ground |
| 24 | CP | Charge pump reservoir - connects to VBB via 0.22 µF capacitor to sustain high-side gate voltage |
Key Features
| Feature | Design Value |
|---|---|
| Programmable current-decay modes | Mixed/fast/slow decay configured via serial bits D17/D13 - enables precise torque and braking control without external logic |
| Synchronous rectification | Active/passive mode selectable via D11/D12 - reduces power dissipation by replacing body diode conduction with low-rDS(on) FET paths |
| Integrated charge pump & VREG | Dual internal supplies eliminate need for external high-side gate drivers or LDOs - simplifies BOM and layout |
| Serial 3-wire interface | 20-bit register (D0–D19) accessible via CLOCK/DATA/STROBE - allows runtime reconfiguration of PWM timing and protection thresholds |
| Comprehensive fault protection | Thermal shutdown (165°C), UVLO (4.2 V), CP/VREG undervoltage detection - disables outputs before damage occurs |
Applications
| Industrial Conveyor Control | Medical Infusion Pump Drive |
|---|---|
Use Scenario: Precise speed and direction control of 24 V DC conveyor belt motors in factory automation systems with variable load inertia. IC Role / Device Role / Timing Role: Full-bridge PWM motor driver executing bidirectional commutation and current-regulated acceleration/deceleration profiles. Use Value: Programmable mixed-decay mode minimizes audible noise during low-speed operation while maintaining torque stability across duty cycles. |
Use Scenario: Low-noise, highly reliable actuation of peristaltic pump motors in Class II medical devices requiring fail-safe current limiting. IC Role / Device Role / Timing Role: Safety-critical motor controller enforcing strict ±1.5 A current limit via external sense resistor and internal comparator with 5 mV offset. Use Value: Thermal shutdown with 15°C hysteresis prevents overheating during extended stall conditions, supporting IEC 60601-1 compliance. |
| Automated Gate Operator | Lab Equipment Positioning Stage |
Use Scenario: High-torque opening/closing of heavy-duty sliding gates powered from 48 V battery backup systems. IC Role / Device Role / Timing Role: Robust H-bridge driver managing inrush current, regenerative braking, and stall detection via sense voltage monitoring. Use Value: Synchronous rectification enabled in active mode eliminates need for external Schottky diodes, reducing board space and forward voltage drop losses. |
Use Scenario: Micro-stepped linear motion control in optical alignment stages requiring smooth velocity transitions and minimal vibration. IC Role / Device Role / Timing Role: Precision current-regulated driver using serial-programmable blank time (4/fOSC–24/fOSC) to suppress switching transients during direction reversal. Use Value: Fixed-off-time PWM architecture ensures consistent current ripple amplitude independent of motor back-EMF, improving 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 |
|---|---|---|---|
| A3958SB | ±2 A continuous output rating, identical pinout and serial interface - higher current capability with same footprint | Supports larger motors requiring >1.5 A peak current; shares same thermal design constraints but higher power dissipation | Select when motor RMS current exceeds 1.5 A and board layout cannot accommodate SOIC upgrade |
| TB6612FNG | 2-channel H-bridge, 1.2 A per channel, no serial interface - uses PHASE/EN pins only, no programmable decay modes | Lacks mixed-decay control and synchronous rectification programming; simpler integration but less flexible current shaping | Choose for cost-sensitive, lower-current designs where fixed decay behavior suffices and serial configuration is unnecessary |
Compared with A3948SB, A3958SB offers higher output current in identical DIP packaging but requires updated thermal management, while TB6612FNG provides basic dual-H-bridge functionality without serial programmability-making it suitable for fixed-function implementations where decay mode tuning is not required.
Availability
A3948SB is available at Aetrix Electronics and suitable for industrial motion control, medical device actuation, and automated access systems requiring stable component supply despite end-of-life status.
Supply support for A3948SB 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 precision power ICs for motion control and energy-efficient systems.
The A3948SB belongs to Allegro's legacy DMOS full-bridge motor driver product line, engineered for robust PWM-controlled DC motor applications in industrial, medical, and building automation where programmable current decay and integrated protection are critical.
FAQ
What is the package type and thermal performance of the A3948SB?
The A3948SB uses a 24-pin plastic DIP with copper batwing tab grounded to PCB. Its thermal resistance is RθJA = 40°C/W on a standard two-layer board, enabling ±1.5 A continuous operation with appropriate copper pour and airflow. The power tab requires no electrical isolation and must be connected to system ground.
How does the A3948SB implement current regulation and decay control?
The A3948SB regulates motor current using an internal fixed-off-time PWM circuit triggered by voltage across an external sense resistor (RS). Decay mode-slow, fast, or mixed-is selected via serial bits D17 and D13, with mixed mode allowing programmable fast-decay duration within the off-time window to balance torque ripple and efficiency.
Can the A3948SB be used with external PWM signals instead of its internal timer?
Yes, the A3948SB supports external PWM control via the ENABLE input. When configured via serial bit D13, ENABLE chopping operates in either fast or slow decay mode. PHASE remains active for direction control, and synchronous rectification can be enabled independently via D12 for reduced conduction loss.
What protection features are built into the A3948SB?
The A3948SB includes thermal shutdown (165°C junction, 15°C hysteresis), UVLO on VDD (4.2 V enable threshold), charge pump (CP) and VREG undervoltage detection, and crossover-current protection. All protections disable outputs until fault conditions clear, ensuring safe recovery without external supervision.
Is the A3948SB still recommended for new designs?
No-the A3948SB is a discontinued product. Allegro MicroSystems states it should not be purchased for new design applications, and samples are no longer available. Designers should evaluate A3958SB (higher current, same DIP package) or modern alternatives like TB6612FNG for new projects requiring full-bridge functionality.
A3948SB 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:
- Serial
- Technology:
- DMOS
- Step Resolution:
- -
- Applications:
- General Purpose
- Current - Output:
- 1.5A
- Voltage - Supply:
- 4.5V ~ 5.5V
- Voltage - Load:
- 20V ~ 50V
- Operating Temperature:
- -20°C ~ 150°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Through Hole
- Supplier Device Package:
- 24-DIP
A3948SB FAQ
1.How can I place an order for A3948SB through Aetrix?
Please submit a Request for Quotation (RFQ) for A3948SB 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 A3948SB reliable?
The price and inventory of A3948SB are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for A3948SB is usually 5 days.
3.What payment methods are accepted for A3948SB?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for A3948SB transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for A3948SB?
A3948SB orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your A3948SB 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 A3948SB?
For technical support, including A3948SB datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your A3948SB requirements.
6.How does Aetrix verify that A3948SB is sourced from the original manufacturer or authorized distributors?
All A3948SB 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 A3948SB meets industry standards.
7.What is the process for return or replacement of A3948SB?
All A3948SB units undergo pre-shipment inspection (PSI). If there is an issue with A3948SB, 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 A3948SB part is unused and in its original packaging.
Return procedure for A3948SB:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
A3948SB Tags
-
DRV2603RUNR
Texas Instruments
-
DRV8837CDSGR
Texas Instruments
-
DRV8837DSGR
Texas Instruments
-
DRV8838DSGR
Texas Instruments
-
DRV8839DSSR
Texas Instruments
-
EMC2301-1-ACZL-TR
Microchip Technology
-
DRV8231ADSGR
Texas Instruments
-
EMC2302-2-AIZL-TR
Microchip Technology
-
DRV8800PWPR
Texas Instruments
-
DRV8835DSSR
Texas Instruments
-
EMC2303-1-KP-TR
Microchip Technology
-
DRV8876PWPR
Texas Instruments
Tech Hub
A practical engineering and sourcing framework covering lifecycle verification, lifetime-buy calculations, replacement qualification, supplier checks and counterfeit-risk controls.
TTL and CMOS logic families differ in thresholds, loading, output drive, power and timing. This engineering guide compares 74HC and 74HCT, calculates noise margins and checks 3.3 V/5 V compatibility.
A practical engineering guide to 3.3V and 5V logic compatibility, input thresholds, resistor dividers, translator ICs, MOSFET level shifting, I2C pull-ups, timing limits and power-sequencing risks.
The 74HC595 uses push-pull logic outputs, while the TPIC6B595 uses 50 V open-drain DMOS sinks for higher-power loads. This guide compares timing, current limits, 3.3 V interfacing, load wiring, thermal…
The 74HC595 converts serial data into eight stable parallel outputs. This guide covers pin functions, shift and storage timing, OE and MR behavior, drive-current limits, cascading, voltage compatibilit…
A technical comparison of level-sensitive latches and edge-triggered flip-flops, covering timing windows, setup and hold limits, master–slave operation, time borrowing, race-through, HDL inference and…
A D latch stores one bit while Enable controls when data can pass. This reference covers gate-level operation, truth tables, transparency, setup and hold timing, LE versus OE, common ICs and practical …
An SR latch stores one bit through cross-coupled feedback. This engineering reference covers NOR and NAND implementations, truth tables, forbidden-state recovery, gated operation, switch debouncing, fa…
Latch circuits retain one bit through feedback. This technical reference covers SR and D latches, truth tables, transparency, timing limits, latch-versus-flip-flop behavior, applications and common log…
An engineering guide to LED driver operation, constant-current and constant-voltage outputs, linear and switching topologies, dimming, IC selection, calculations, replacement compatibility, and fault c…
