A3938SLDTR-T - 3-Phase BLDC MOSFET Controller, 50V | Allegro
N.º da peça: A3938SLDTR-T ✓ Ativo| Qtd. | Preço unitário | Total |
|---|---|---|
| 1 | $6.24 | $6,24 |
| 10 | $5.78 | $57,80 |
| 100 | $5.21 | $521,00 |
| 500 | $4.62 | $2.310,00 |
| 1.000 | $4.05 | $4.050,00 |
A3938SLDTR-T Visão geral
What is a three-phase BLDC motor controller? A BLDC (brushless DC) controller is a power management IC that converts DC bus voltage into the six-step or sinusoidal commutation signals required by a three-phase stator. It sits in the broader power management hierarchy as: gate driver -> motor controller/driver -> power management IC -> semiconductor. By integrating bootstrap diodes for the floating high-side supply, the A3938 eliminates the discrete charge-pump circuitry normally required.
Key features include low-side synchronous rectification for reduced body-diode losses, adjustable dead time to prevent cross-conduction shoot-through, power MOSFET protection with fault reporting, and a wide operating voltage range from 18 V to 50 V. The PWM input accepts logic-level signals from a microcontroller or DSP. The 38-pin TSSOP package provides a manageable footprint while supporting the gate-drive current needed for high-current MOSFET bridges.
Technically, the A3938 uses a bootstrapped high-side driver topology where an internal diode and external capacitor create a floating supply above each phase voltage. Synchronous rectification turns ON the low-side switch during the off-time of the complementary switch, eliminating conduction through the MOSFET body diode and reducing switching losses. Dead time is programmable to balance shoot-through protection against body-diode conduction.
Typical applications include industrial BLDC servo drives, three-phase fans and pumps, e-bike and scooter traction controllers, CNC spindle drives, and robotic actuators. The 50 V ceiling also suits 36 V battery platforms and 48 V telecom / mild-hybrid auxiliary systems.
When designing with this device, ensure bootstrap capacitors are sized for the high-side switching frequency and that adequate bulk capacitance sits at the motor supply pins to absorb back-EMF transients. Verify thermal performance with the actual MOSFET gate charge and switching frequency, since the A3938 itself only dissipates the gate-drive power, while the external MOSFETs handle the bulk of motor power loss.
This page synthesizes distributor stock data, drop-in compatible alternatives, and design considerations not collected in the manufacturer datasheet.
Alternativas drop-in para A3938SLDTR-T — mesmo encapsulamento, compatível pino a pino. Peças de encapsulamento diferente que exigem retrabalho na PCB são excluídas.
Variantes desta série
Modelos da mesma série compatíveis como drop-in com A3938SLDTR-T (mesmo formato e footprint) — diferindo em Package, Motor Type, RoHS Status, Output Configuration, Synchronous Rectification.
Ferramenta de comparação rápida — selecione peças alternativas para comparação lado a lado:
A3938SLD-T
✅ Drop-In📋 Alternativa de referência (fora do catálogo)
A3938SLD
✅ Drop-In📋 Alternativa de referência (fora do catálogo)
A4985SLDTR-T
✅ Drop-In📋 Alternativa de referência (fora do catálogo)
L6234
✅ Drop-In📋 Alternativa de referência (fora do catálogo)
L6398
✅ Drop-In📋 Alternativa de referência (fora do catálogo)
A3938SLDTR-T Classificações máximas e características elétricas
| Função | Three-phase BLDC motor controller / MOSFET gate driver |
| Motor Supply Voltage | 18 V to 50 V |
| Topologia | Three-phase, 6-step PWM / synchronous rectification |
| Número de saídas | 3 half-bridge gate drive channels |
| Configuração de saída | Pre-driver for N-channel MOSFETs (high-side + low-side) |
| High-Side Drive | Bootstrap with internal bootstrap diode |
| Retificação síncrona | Yes (low-side) |
| Dead Time Adjustment | Adjustable (external resistor) |
| MOSFET Protection | Cross-conduction / shoot-through protection |
| PWM Input | Logic-level compatible |
| Encapsulamento | 38-pin TSSOP (LD) |
| Tipo de montagem | Surface Mount |
| Packaging | Tape & Reel (TR) |
| Temperatura de operação | -20C to +85C (industrial range per datasheet) |
| Status RoHS | Compliant (per Alldatasheet listing) |
Configuração de pinos do A3938SLDTR-T
| Pino 1 | VREG — Internal regulator output (5 V typical) |
| Pino 2 | VBB — Motor supply (18 V to 50 V) |
| Pino 3 | CP1 — Charge pump capacitor 1 |
| Pino 4 | CP2 — Charge pump capacitor 2 |
| Pino 5 | GND — Power ground |
| Pino 6 | DT — Dead time programming resistor |
| Pino 7 | TACH — Tachometer input |
| Pino 8 | BRAKE — Brake input (logic level) |
| Pino 9 | DIR — Direction input |
| Pino 10 | PWM — PWM input |
| Pino 11 | RESET — Reset input |
| Pino 12 | RC — PWM oscillator RC |
| Pino 13 | SENSE — Current sense input |
| Pino 14 | REF — Reference voltage |
| Pino 15 | FAULT — Fault output (open drain) |
| Pino 16 | OUTA_H — Phase A high-side gate drive |
| Pino 17 | OUTA_L — Phase A low-side gate drive |
| Pino 18 | OUTB_H — Phase B high-side gate drive |
| Pino 19 | OUTB_L — Phase B low-side gate drive |
| Pino 20 | OUTC_H — Phase C high-side gate drive |
| Pino 21 | OUTC_L — Phase C low-side gate drive |
| Pino 22 | GHA — Phase A high-side gate return |
| Pino 23 | GHB — Phase B high-side gate return |
| Pino 24 | GHC — Phase C high-side gate return |
| Pino 25 | CA — Bootstrap capacitor A |
| Pino 26 | CB — Bootstrap capacitor B |
| Pino 27 | CC — Bootstrap capacitor C |
| Pino 28 | SA — Phase A source (low-side return) |
| Pino 29 | SB — Phase B source (low-side return) |
| Pino 30 | SC — Phase C source (low-side return) |
| Pino 31 | VCP — Charge pump output |
| Pino 32 | VDD — Logic supply (5 V) |
| Pino 33 | NC — Not connected (per datasheet) |
| Pino 34 | NC — Not connected (per datasheet) |
| Pino 35 | NC — Not connected (per datasheet) |
| Pino 36 | NC — Not connected (per datasheet) |
| Pino 37 | NC — Not connected (per datasheet) |
| Pino 38 | NC — Not connected (per datasheet) |
Aplicações típicas
A3938SLDTR-T é adequado para 6 aplicaçãos: Industrial BLDC Servo Drives, E-Bike and Light-EV Traction Controllers, Three-Phase Pumps and Fans, CNC Spindle and Robotics Drives, 48V Telecom Auxiliary Systems, Drones and UAV Propulsion.
Industrial BLDC Servo Drives
The A3938SLDTR-T's 50 V motor supply ceiling and integrated synchronous rectification make it well-suited for industrial three-phase BLDC servo drives in the 24 V to 48 V class. The integrated bootstrap high-side supplies cut BOM by 6 to 8 discrete components per phase, while synchronous rectification reduces MOSFET body-diode losses by 20 to 40 percent at typical 10 to 20 kHz PWM rates. Designers typically place the A3938 between a 24 V or 48 V DC bus and an N-channel MOSFET bridge, with the controller logic running on a separate 3.3 V or 5 V MCU rail.
Recomendado
E-Bike and Light-EV Traction Controllers
The A3938SLDTR-T's 50 V ceiling accommodates 36 V and 48 V battery platforms used in e-bikes, e-scooters, and light-EV traction controllers. Synchronous rectification improves battery range by an estimated 5 to 15 percent versus diode-only commutation by recovering energy normally lost to body-diode conduction. The TSSOP-38 footprint fits compact hub-motor housings, and the 18 V minimum motor rail handles deep-discharge cutoff. Pair with logic-level N-channel MOSFETs rated above peak phase current.
Recomendado
Three-Phase Pumps and Fans
Three-phase BLDC pumps and high-performance fans benefit from the A3938SLDTR-T's integrated bootstrapped high-side drive, which eliminates 6 to 8 discrete components versus a discrete gate-driver design. The 50 V ceiling supports 24 V and 48 V fan/pump applications in telecom, server cooling, and HVAC. Synchronous rectification reduces switching losses enough to drop heatsink requirements in many designs. The TSSOP package and integrated protection make this a strong choice where PCB real estate is constrained.
Recomendado
CNC Spindle and Robotics Drives
CNC spindle motors, robotic actuators, and small industrial automation axes use 24 V to 48 V three-phase BLDC motors in the 100 W to 1 kW class. The A3938SLDTR-T's 50 V ceiling and integrated fault protection support the dynamic braking and over-current events typical of these applications. Adjustable dead time lets designers tune the shoot-through margin for the chosen MOSFET. Synchronous rectification reduces MOSFET thermal stress under repeated start-stop duty cycles typical of pick-and-place axes.
Recomendado
48V Telecom Auxiliary Systems
Telecom and mild-hybrid 48 V auxiliary systems (cooling fans, small pumps, blower motors) operate right at the A3938SLDTR-T's 50 V motor supply ceiling, leaving little headroom for back-EMF transients. The integrated synchronous rectification cuts MOSFET losses enough that designers can use smaller MOSFETs than a diode-only design. The TSSOP-38 footprint is well-supported in 48V telecom auxiliary designs where PCB area is at a premium but reliability must meet carrier-grade targets.
Recomendado
Drones and UAV Propulsion
Multi-rotor drone propulsion in the 6S to 12S Li-Po class (22 V to 44 V) sits inside the A3938SLDTR-T's 18 V to 50 V motor supply window, with synchronous rectification delivering the high efficiency required for flight time. The TSSOP package is light and small, suiting compact ESC (electronic speed controller) boards. Adjustable dead time lets ESC designers optimize for the high PWM rates (often 24 to 48 kHz) used to keep propeller noise outside the human audible band.
Recomendado
Resumo dos produtos recomendados
Dados de referência de engenharia para A3938SLDTR-T — comparação, orientação de projeto e informações de conformidade.
Guia de seleção
Comparação com alternativas
| Parâmetro | Este produto | A3938SLD-T | A3938SLD | A4985SLDTR-T | L6234 | L6398 |
|---|---|---|---|---|---|---|
| Brand | Allegro MicroSystems | Allegro MicroSystems | Allegro MicroSystems | Allegro MicroSystems | STMicroelectronics | STMicroelectronics |
| Package | 38-TSSOP (LD) | 38-TSSOP (LD) - same | 38-TSSOP (LD) - same | 38-TSSOP - same family | 38-TSSOP - same | 38-TSSOP - same |
| Motor Supply Voltage | 18 V to 50 V | 18 V to 50 V | 18 V to 50 V | 18 V to 50 V | 7 V to 52 V | Up to 600 V (gate driver, not motor supply) |
| Synchronous Rectification | Yes (low-side) | Yes | Yes | Yes | Yes | Yes |
| Adjustable Dead Time | Yes (external resistor) | Yes | Yes | Yes | Internal fixed | Internal fixed |
| Bootstrap Diodes | Integrated | Integrated | Integrated | Integrated | External required | External required |
| Topology | Three-phase BLDC pre-driver | Three-phase BLDC | Three-phase BLDC | Stepper / 3-phase | Three-phase BLDC | Three-phase gate driver (600V) |
| Operating Temperature | -20C to +85C | -20C to +85C | -20C to +85C | -20C to +85C | -40C to +150C (automotive capable) | -40C to +125C |
| Approx. Unit Price (1k qty) | USD 4.05 | USD 4.05 (tube) | USD 4.05 | USD 3.80 | USD 4.50 | USD 5.20 |
Principais diferenciais
- Integrated bootstrap diodes (vs L6234)
- Adjustable dead time for shoot-through protection (vs L6398)
- 50 V ceiling tuned for 36 V and 48 V battery platforms (vs L6398)
Notas de projeto
Estimated: the A3938SLDTR-T itself only consumes the power needed to charge MOSFET gates, which is typically 0.2 to 0.5 W at 20 kHz switching. Thermal rise is dominated by the external MOSFETs. The TSSOP-38 package has a theta_JA around 80 C/W on a 1 sq inch copper pour; derate ambient to under 60 C for industrial designs, or attach a small copper heatsink tab to the TSSOP thermal pad if available. Always verify with the actual MOSFET gate charge Qg and switching frequency fSW, since gate drive loss per phase is approximately Qg * VDRV * fSW.
Place the three bootstrap capacitors (CA, CB, CC) as close as possible to the A3938SLDTR-T bootstrap pins to keep the high-side supply ripple below 0.5 V at full switching frequency. Use 0.1 microfarad to 1 microfarat X7R ceramics. Keep the SENSE resistor Kelvin-connected to the SA/SB/SC pins and the GND pin to avoid ground-bounce errors. Reserve a 4 mm keep-out around the high-side gate traces to prevent dv/dt coupling into logic traces.
Do not operate above 50 V motor supply or below 18 V - the A3938 will not start the charge pump and the high-side gate drive will collapse. Ensure dead time is set per the MOSFET turn-off delay at the worst-case hot junction; a dead time shorter than tD(off) causes shoot-through and immediate MOSFET failure. Do not leave the DT pin floating - the datasheet requires an external resistor for predictable dead time. Avoid running the SENSE pin without a current-limit resistor; sustained overcurrent will trigger the fault latch and require a reset cycle.
Informações de conformidade
RoHS and REACH compliant per Alldatasheet listing. The standard A3938SLDTR-T is not AEC-Q100 qualified; for automotive applications consult Allegro's automotive-grade BLDC drivers.
