STMicroelectronics L297D

Overview

L297D from STMicroelectronics is a dedicated stepper motor controller IC for bipolar and unipolar two-phase/four-phase motors, supporting half-step, normal (two-phase-on), and wave (one-phase-on) drive modes with internal PWM chopper current regulation, 5 V supply operation, and programmable peak current via Vref (0–3 V). It interfaces with bridge drivers like L298N and reduces microprocessor burden by generating phase sequences internally.

For engineers reviewing the L297D datasheet, L297D pinout, L297D application, or L297D equivalent, key selection considerations include chopper control mode (CONTROL pin), synchronous multi-controller configuration (SYNC/OSC), step timing constraints (tCLK = 0.5 µs, tR = 1 µs), and compatibility with discrete or monolithic power stages for industrial motion control.

Technical Context

The L297D integrates a state-machine translator that outputs four-phase logic signals (A/B/C/D) and dual active-low inhibit lines (INH1/INH2), with sequencing determined by CLOCK edge, HALF/FULL level, and CW/CCW state. Its on-chip oscillator (f ≅ 1/(0.69·RC)) drives two independent PWM comparators comparing SENS1/SENS2 to Vref to regulate winding current.

Chopper action is configurable via CONTROL pin: when low, INH1/INH2 are chopped for fast decay in unipolar or L298N-based bipolar configurations; when high, phase outputs ABCD are chopped, enabling non-active-phase activation to reduce sense resistor dissipation. RESET forces translator to home state (ABCD = 0101), and SYNC enables synchronization across multiple L297Ds.

Key Specifications

Pinout & Package

Package: SO20 (Small Outline, 20-pin, 0.5 mm pitch, body size 12.6 × 7.6 mm, height ≤ 2.65 mm).

Key Features

Applications

Equivalent & Alternatives

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

Compared with TB6560AHQ and LV8729V, the L297D offers unique hardware-level synchronization (SYNC), deterministic home-state signaling (HOME), and flexible chopper targeting (CONTROL pin), making it optimal for cost-sensitive, multi-axis open-loop systems requiring precise timing coordination and minimal external components.

Availability

L297D is available at Aetrix Electronics and suitable for industrial CNC positioning, printer paper feed mechanisms, lab automation dispensing systems, and medical infusion pump actuation requiring stable component supply and long-term lifecycle support.

Supply support for L297D 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

STMicroelectronics is a global semiconductor leader headquartered in Geneva, Switzerland, designing and manufacturing analog, mixed-signal, power, and microcontroller products for industrial, automotive, and consumer markets.

The L297D belongs to ST's legacy motor control IC portfolio, engineered specifically for cost-effective, robust open-loop stepper motion in resource-constrained embedded systems - emphasizing simplicity, thermal resilience, and interoperability with discrete or monolithic power stages.

FAQ

What is the function of the CONTROL pin on the L297D?

The CONTROL pin selects chopper modulation target: when low, PWM regulates INH1/INH2 for fast current decay in unipolar or L298N-based bipolar drives; when high, PWM modulates phase outputs A/B/C/D, enabling non-active-phase activation to reduce sense resistor heating. This choice directly impacts thermal performance and torque consistency.

Can the L297D drive a unipolar stepper motor directly?

No - the L297D is a controller only and requires external power devices. For unipolar motors, it drives quad Darlington arrays (e.g., ULN2003) or discrete transistors via A/B/C/D outputs, with chopper action applied to INH1/INH2 (CONTROL = low) to manage winding current decay timing and prevent saturation.

How does the HOME output work, and what is its electrical behavior?

The HOME pin is an open-collector output that pulls low when the translator is in its initial state (ABCD = 0101). It remains high-impedance otherwise. A pull-up resistor (typically 4.7 kΩ to 5 V) is required. This signal provides hardware-level position reference without software polling or encoder dependency.

What is the maximum recommended operating temperature for continuous use?

The L297D has a junction temperature limit of +150°C and a thermal resistance of 100 °C/W in SO20 package. At ambient 70°C and 1 W dissipation, junction temperature reaches 170°C - exceeding rating. Derating to 0.7 W max at 70°C ensures Tj ≤ 140°C, meeting industrial reliability requirements for continuous operation.