Texas Instruments UC3625DWTR

Overview

UC3625DWTR from Texas Instruments is a brushless DC motor controller IC designed for fixed-frequency PWM voltage- or current-mode control of 3-phase BLDC motors. It integrates high-side (50-V open-collector) and low-side (push-pull) gate drivers, a high-speed current-sense amplifier with ideal diode, latched soft-start, tachometer output, and programmable cross-conduction protection. It operates across 0°C to +70°C and supports two- or four-quadrant operation in robotics and industrial motion systems.

For engineers reviewing the UC3625DWTR datasheet, UC3625DWTR pinout, UC3625DWTR application, or UC3625DWTR equivalent, this page delivers verified technical context on oscillator configuration (ROSC/COSC), direction latch timing, pulse-by-pulse vs. average current sensing, brake mode entry via RC-BRAKE, and safe reversal logic - all critical for motor control layout, fault response tuning, and thermal design.

Technical Context

The UC3625DWTR implements closed-loop speed control using a tachometer feedback signal derived from Hall sensor transitions, with internal averaging and noise-blanking latches that hold for two PWM cycles (e.g., 50–100 µs at 20–40 kHz). Its direction reversal logic uses a two-bit shift register clocked by the internal oscillator to enforce ≥25 µs dead time between opposing drive signals, preventing cross-conduction.

Current regulation is supported in both pulse-by-pulse (via ISENSE1/ISENSE2 differential inputs with 2× gain and 2.5 V level shift) and average modes (enabled by QUAD SEL high and RD resistor in four-quadrant topology). The error amplifier features unity-gain stability, allowing direct feedback from E/A OUT to E/A IN(–), and its output clamps at SSTART voltage during soft-start sequencing.

Key Specifications

Pinout & Package

UC3625DWTR is packaged in a 28-pin SOIC (DW) with 300-mil body width and standard JEDEC MS-013AC footprint. Pin functions are identical across SOIC (DW), PLCC (Q), and LCC (L) packages per TI SLUS353C.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar brushless DC motor controller applications.

Compared with UC2625DWTR, UC3625DWTR trades extended temperature capability for lower cost and simpler qualification in commercial equipment; compared with MP6532DS-LF-Z, it eliminates MCU dependency but lacks digital configurability and FOC support.

Availability

UC3625DWTR is available at Aetrix Electronics and suitable for industrial robotics, automated material handling, electric linear actuators, and medical infusion pump motor drives requiring stable component supply across production lifecycles.

Supply support for UC3625DWTR 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

Texas Instruments is a global semiconductor leader specializing in analog, embedded processing, and power management technologies, with decades of expertise in motor control ICs and industrial interface solutions.

The UC3625DWTR belongs to TI's UCx625 family of integrated BLDC motor controllers, designed specifically for cost-sensitive, high-reliability analog motor drives where deterministic timing, hardware-enforced safety, and minimal external components are prioritized over digital programmability.

FAQ

What is the maximum recommended oscillator frequency for UC3625DWTR?

The UC3625DWTR oscillator is characterized up to 65 kHz (max) across temperature and supply voltage. While the datasheet notes frequencies below 500 kHz are possible with external RC networks, stable operation above 65 kHz risks degraded timing accuracy, reduced tachometer pulse fidelity, and increased jitter in direction latch and cross-conduction protection logic. For reliable performance, keep ROSC × COSC product yielding ≤65 kHz - e.g., ROSC = 20 kΩ and COSC = 2 nF gives ~50 kHz typical.

How does UC3625DWTR implement safe direction reversal?

The UC3625DWTR implements safe direction reversal using a two-stage hardware latch: first, DIR input is loaded into a transparent latch only when SPEED-IN voltage falls below 257 mV (indicating low motor speed); second, the latch output feeds a two-bit shift register clocked by the internal oscillator, enforcing a minimum 25–50 µs delay before new direction commands propagate to drivers. This prevents abrupt reversal while stored kinetic energy remains high, eliminating mechanical stress and power device shoot-through.

Can UC3625DWTR drive N-channel MOSFETs on both high-side and low-side?

UC3625DWTR directly drives N-channel MOSFETs on the low-side via PDA/PDB/PDC push-pull outputs (active-high). For high-side N-MOSFETs, it requires external level-shifting circuitry - such as transformer-isolated drivers (e.g., UC3724/UC3725), optocouplers with ≥10 V boost supply, or cascode transistor stages - because its PUA/PUB/PUC outputs are 50-V open-collector (active-low) and cannot self-generate gate voltages above VMOTOR.

What is the function of the SSTART pin on UC3625DWTR?

The SSTART pin on UC3625DWTR controls soft-start sequencing by clamping the error amplifier output voltage (E/A OUT) to its voltage level. During fault recovery or power-up, an internal transistor discharges the external SSTART capacitor; as the capacitor recharges via the on-chip current source, E/A OUT gradually rises, enabling increasing PWM duty cycle. This ensures controlled motor acceleration without current surge, and a 51-kΩ resistor from VREF to SSTART guarantees proper switching threshold.

Does UC3625DWTR support both two-quadrant and four-quadrant motor operation?

Yes, UC3625DWTR supports both modes via the QUAD SEL pin (Pin 22). In two-quadrant mode (QUAD SEL = low), only low-side drivers (PDA/PDB/PDC) are PWM-chopped while high-sides remain on - efficient for unidirectional applications with regenerative braking via diodes. In four-quadrant mode (QUAD SEL = high), all six drivers are chopped, enabling full bidirectional torque control, equal acceleration/deceleration, and active braking - essential for servo positioning and dynamic load handling.