STMicroelectronics L293B

Overview

L293B from STMicroelectronics is a quad push-pull driver IC designed for bidirectional DC motor and solenoid control in embedded motion systems. It delivers 1A continuous output current per channel, supports 36V supply voltage, features separate logic supply (4.5–36V), and includes thermal shutdown and inhibit control. Used in robotics actuation, printer carriage drives, and industrial valve control.

For engineers reviewing the L293B datasheet, L293B pinout, L293B application, or L293B equivalent, key selection criteria include per-channel current capability (1A), TTL-compatible inputs, independent logic supply rail, thermal protection behavior, and DIP-16 package thermal management via ground-pin heat conduction.

Technical Context

The L293B integrates four independent half-H-bridge drivers with complementary NPN-PNP push-pull output stages. Each channel accepts TTL-level logic inputs and features dedicated enable (inhibit) control that forces high-impedance output state across all transistors when asserted low.

It uses a dual-supply architecture: Vs powers the output stage (up to 36V), while Vss supplies the logic section (4.5–36V), enabling low-voltage microcontroller interfacing without level-shifting. Internal thermal shutdown activates at junction temperature >150°C.

Key Specifications

Pinout & Package

Package: 16-pin plastic DIP (Dual In-line Package), 0.3" wide, with pins 4, 5, 12, and 13 internally connected to substrate ground and externally used for thermal conduction to PCB copper area.

Key Features

Applications

Equivalent & Alternatives

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

Compared with TB6612FNG and L298N, the L293B offers unique value in through-hole prototyping, TTL-native interfacing, and thermal management via standard DIP ground pins - making it optimal for education, test fixtures, and low-volume industrial controls where ease of assembly and debug matters.

Availability

L293B is available at Aetrix Electronics and suitable for robotics actuation, printer carriage drives, bipolar stepper motor control, and industrial solenoid sequencing requiring stable component supply and long-lifecycle support.

Supply support for L293B 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, designing and manufacturing analog, MCU, power, and sensor solutions for industrial, automotive, and consumer markets.

The L293B belongs to ST's legacy power driver product line, engineered specifically for cost-sensitive, medium-current motion control applications where robustness, simplicity, and through-hole manufacturability are prioritized over ultra-low R_DS(on) or integrated diagnostics.

FAQ

What is the maximum continuous output current per channel for the L293B?

The L293B supports 1A continuous output current per channel under conditions where junction temperature remains ≤150°C. This requires adequate PCB copper area on pins 4, 5, 12, and 13 to maintain thermal resistance ≤40°C/W. Peak current of 2A is allowed for ≤5ms non-repetitive pulses.

Can the L293B operate with a 3.3V microcontroller logic supply?

Yes - the L293B's logic supply (Vss) accepts 4.5V to 36V, but its TTL-compatible inputs (ViL ≤1.5V, ViH ≥2.3V) reliably recognize 3.3V logic HIGH from modern MCUs. A 3.3V Vss is not supported; instead, use 5V for Vss and connect MCU GPIOs directly to IN/INH pins.

How does the inhibit function work on the L293B?

The L293B has two independent inhibit inputs: INH1 (pin 1) disables channels 1 and 2, while INH2 (pin 9) disables channels 3 and 4. When pulled LOW, both outputs of the associated pair enter high-impedance state - effectively disconnecting the motor windings and enabling fast, zero-current braking or coasting.

Is a heatsink required for 1A operation?

A dedicated heatsink is not required if the L293B's four GND pins (4, 5, 12, 13) are soldered to ≥2 cm² of 2-oz copper on the PCB - this achieves R_th(j-amb) ≈ 40°C/W. At 1A and 12V, power dissipation is ~1.8W; with ambient ≤60°C, junction temperature stays below 140°C. Forced air or external heatsink is needed only above 1.2A continuous.