STMicroelectronics L293DD

Overview

L293DD from STMicroelectronics is a monolithic high-voltage, high-current quad push-pull driver IC with integrated clamp diodes, designed to interface TTL/DTL logic with inductive loads such as DC motors, stepper motors, relays, and solenoids. It delivers 600 mA continuous output current per channel, supports up to 36 V supply voltage (VS), includes independent enable inputs for two dual-channel bridges, and features overtemperature protection.

For engineers reviewing the L293DD datasheet, L293DD pinout, L293DD application, or L293DD equivalent, key selection considerations include per-channel 600 mA continuous drive capability, separate logic supply (VSS) support down to 4.5 V, internal clamping diodes eliminating external flyback components, and thermal design implications of its SO20 package with 8-pin heatsink pad.

Technical Context

The L293DD implements four independent half-H-bridge outputs arranged as two logically paired channels, each with dedicated enable (EN1, EN2) controlling both outputs simultaneously. Its internal architecture integrates bipolar Darlington transistor pairs per output leg and built-in bidirectional clamp diodes across each output terminal to suppress inductive kickback.

It operates with dual supplies: VS (pin 10) powers the output stage (up to 36 V), while VSS (pin 20) powers the logic interface (4.5–36 V), enabling mixed-voltage system integration. Switching performance is rated for frequencies up to 5 kHz, with typical rise/fall times of 250 ns and propagation delays of 750 ns (ton) and 200 ns (toff).

Key Specifications

Pinout & Package

The L293DD is housed in a 20-lead SOIC package (SO20, package code SO(12+4+4)), with pins 5–8 and 13–16 internally connected as an 8-pin thermal pad for PCB heatsinking. Pin 10 is VS (power supply), pin 20 is VSS (logic supply), and pins 1 and 11 are channel enables.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar quad half-H-bridge driver applications.

Compared with TB6612FNG, the L293DD trades lower conduction loss for integrated protection and simpler layout; versus SN754410, it offers identical functionality but distinct manufacturing lineage and qualification history-critical for long-lifecycle industrial deployments.

Availability

L293DD is available at Aetrix Electronics and suitable for DC motor control, stepper motor drive, relay interface, and industrial PLC output modules requiring stable component supply and long-term manufacturability.

Supply support for L293DD 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, specializing in automotive, industrial, and power management ICs with broad analog, digital, and mixed-signal portfolio coverage.

The L293DD belongs to ST's legacy motor driver product line, engineered specifically for cost-sensitive, medium-power motion control applications where integration, reliability, and ease of use outweigh ultra-high efficiency demands.

FAQ

What is the maximum operating temperature for continuous 600 mA output per channel?

The L293DD junction temperature must remain ≤150 °C. With R_{th j-amb} = 50 °C/W (and 6 cm² PCB heatsink), continuous 600 mA operation at 24 V VS requires ambient ≤70 °C. Derating is mandatory above this; thermal shutdown activates if T_j exceeds threshold.

Can L293DD drive a unipolar stepper motor directly?

No-it lacks the center-tap switching topology required for unipolar stepper excitation. It is optimized for bipolar 4-wire steppers using full-bridge current reversal. Unipolar motors require separate transistor arrays or dedicated unipolar drivers like ULN2003.

Is separate decoupling required for VS and VSS pins?

Yes. VS (pin 10) requires ≥100 µF electrolytic + 100 nF ceramic near the pin to handle motor current transients. VSS (pin 20) needs ≥10 µF + 100 nF to suppress logic supply noise. Shared decoupling risks coupling motor noise into the control interface.

Does the L293DD support PWM frequencies above 5 kHz?

No-its specified switching limit is 5 kHz due to propagation delays (750 ns ton) and output capacitance. Attempting higher frequencies causes incomplete switching, increased heating, and potential shoot-through. For >10 kHz PWM, consider MOSFET-based drivers like DRV8871.