Texas Instruments / STMicroelectronics · Integrated circuit

L293D Motor Driver

Quad half-bridge with built-in flyback diodes: two DC motors bidirectionally, or one bipolar stepper. Old, inefficient and still the part in every starter kit.

Cheat sheet (SVG)

Logic level: 4.5-7 V logic / ≤36 V motor
Package: PDIP-16 / SOIC-16 (PowerDIP with fused GND)

1.Pinout diagram

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Pins 1-8

L293D

Pins 9-16

Pin detail

Hover a pin for its mappings and gotchas. Click to keep it here.

Logic level: 4.5-7 V logic / ≤36 V motor
Package: PDIP-16 / SOIC-16 (PowerDIP with fused GND)

Fig. 1. L293D Motor Driver, PDIP-16. Hover or tap a signal to light up every pin that carries it.

2.Watch out

It is a Darlington bridge, so it drops roughly 1.4-1.8 V on each side, about 3 V total. At 6 V in, your motor sees half that. This is the reason to reach for a DRV8833 or TB6612FNG instead.
600 mA continuous per channel, 1.2 A peak. The plain L293 doubles that but has no internal diodes.
The four center pins (4, 5, 12, 13) are both ground and the only heatsink. Solder all four to a copper pour; a DIP socket in still air will thermally shut down.
VCC1 (16) is logic and VCC2 (8) is the motor rail. Both are required, and VCC2 must be at or above VCC1.
The two enable pins take PWM for speed control. PWM on the direction inputs instead works but is noisier and gives a worse low-speed response.
The D in L293D means the clamp diodes are on-die. With a bare L293 you must add eight external Schottkys.

3.Driving one motor

What has to go around the chip before it will run.

Fig. 2. Driving one motor, drawn from Table 1. Dashed parts are optional. Crossing wires are not connected.

Table 1. External parts, and why each one is there.
Part	Between	Why
Wire link	VCC1 (16) to VCC	Logic supply, 4.5 to 7 V. Separate from the motor rail and it must be powered first.
Wire link	VCC2 (8) to VM	Motor supply, up to 36 V. Tying it to the logic rail only works if the motor runs on 5 V.
100 nF	VCC1 (16) to GND	Decoupling on the logic supply at the pin.
100 uF	VCC2 (8) to GND	Bulk on the motor supply. Stall current comes from here, not from the logic rail.
Motor	OUT1 (3) to OUT2 (6)	A brushed motor across one half bridge. IN1 and IN2 set direction, EN1,2 gates both outputs.
Wire linkoptional	EN1,2 (1) to VCC	Enable tied high runs the bridge continuously. Drive it with PWM instead to control speed.

The D suffix is the whole difference: the L293D has the clamp diodes on-die, the plain L293 does not and needs eight external ones. Both drop about 2 V across the output stage, so a 12 V motor on a 12 V rail sees closer to 10 V.

4.Full pin reference

Every pin, alias and mapping. This is the table that prints.

Table 2. Pin assignments.

Complete pin reference for L293D Motor Driver
Pin	Name	Also called	Functions	Notes
1	EN1,2PWM	1,2EN, ENA	Enable channels 1 and 2	High to drive. PWM here for speed control on motor A.
2	IN1	1A	Channel 1 input
3	OUT1	1Y	Channel 1 output	Motor A terminal.
4	GND	-	Ground / heatsink	One of four fused ground pins, the package's entire thermal path.
5	GND	-	Ground / heatsink
6	OUT2	2Y	Channel 2 output	Motor A terminal.
7	IN2	2A	Channel 2 input
8	VCC2VCC1 to 36 V	-	Motor supply	Needs a bulk electrolytic close by; motor current comes from here, not from your 5 V rail.
9	EN3,4PWM	3,4EN, ENB	Enable channels 3 and 4	PWM here for speed control on motor B.
10	IN3	3A	Channel 3 input
11	OUT3	3Y	Channel 3 output	Motor B terminal.
12	GND	-	Ground / heatsink
13	GND	-	Ground / heatsink
14	OUT4	4Y	Channel 4 output	Motor B terminal.
15	IN4	4A	Channel 4 input
16	VCC14.5-7 V	-	Logic supply	Separate from the motor rail. 100 nF at the pin.

Looking for a substitute?

L293D, 4 alternatives

Primary sources

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