Overview

The L293D is a monolithic integrated high-voltage, high-current quadruple half-H driver chip manufactured by Texas Instruments and STMicroelectronics. It is designed to drive inductive loads such as DC motors, bipolar/unipolar stepper motors, relays, and solenoids.

The chip contains 4 independent half-H channels (capable of driving 2 bidirectional DC motors or 1 stepper motor) providing up to 600 mA continuous output current per channel at voltages from 4.5 V to 36 V. The "D" suffix variant integrates internal flyback clamp diodes to suppress inductive voltage spikes.

Quick reference

Motor supply voltage (VCC2 / Pin 8)4.5 V to 36.0 V DC
Logic supply voltage (VCC1 / Pin 16)4.5 V to 7.0 V DC (5 V nominal)
Continuous current per channel600 mA
Peak output current per channel1.2 A (non-repetitive pulse <100 μs<100\text{ }\mu\text{s})
Internal flyback diodesYes (integrated internal clamp diodes to VCC2V_{CC2})
Control logic inputs5V TTL/CMOS compatible (1A–4A, 1,2EN, 3,4EN)
Thermal protectionInternal thermal shutdown protection

Pin configuration

16-Pin DIP / SOIC Package

text
           ┌──────────┐
    1,2EN ──│ 1     16 │── VCC1 (Logic 5V)
       1A ──│ 2     15 │── 4A
       1Y ──│ 3     14 │── 4Y
      GND ──│ 4     13 │── GND
      GND ──│ 5     12 │── GND
       2Y ──│ 6     11 │── 3Y
       2A ──│ 7     10 │── 3A
 VCC2 (M) ──│ 8      9 │── 3,4EN
           └──────────┘
PinNameTypeDescription
11,2ENDigital InputEnable driver channels 1 & 2 (HIGH = Active, LOW = High-impedance)
21ADigital InputDriver 1 input line
31YDriver OutputDriver 1 output line (connect to Motor 1 terminal A)
4, 5GNDPowerGround & Heat sink pins (solder to PCB copper plane)
62YDriver OutputDriver 2 output line (connect to Motor 1 terminal B)
72ADigital InputDriver 2 input line
8VCC2Power InputMotor power supply voltage (+4.5 V to +36 V DC)
93,4ENDigital InputEnable driver channels 3 & 4 (HIGH = Active, LOW = High-impedance)
103ADigital InputDriver 3 input line
113YDriver OutputDriver 3 output line (connect to Motor 2 terminal A)
12, 13GNDPowerGround & Heat sink pins
144YDriver OutputDriver 4 output line (connect to Motor 2 terminal B)
154ADigital InputDriver 4 input line
16VCC1Power InputLogic power supply voltage (+5.0 V DC)

Specifications

ParameterSymbolMinTypMaxUnitConditions
Motor Supply VoltageVCC2V_{CC2}4.512.036.0VDC
Logic Supply VoltageVCC1V_{CC1}4.55.07.0VDC
Continuous Output CurrentIOI_{O}-600—600mAPer channel
Peak Output CurrentIO,peakI_{O,peak}-1.2—1.2At≤100 μst \le 100\text{ }\mu\text{s}, non-repetitive
Input High VoltageVIHV_{IH}2.3—VCC1V_{CC1}VTTL compatible
Input Low VoltageVILV_{IL}-0.3—1.5VTTL compatible
Saturation Voltage (Low)VOLV_{OL}—0.91.2VIO=600 mAI_{O} = 600\text{ mA}
Saturation Voltage (High)VOHV_{OH}VCC2−1.8V_{CC2}-1.8VCC2−1.4V_{CC2}-1.4—VIO=−600 mAI_{O} = -600\text{ mA}
Thermal Shutdown TempTJSDT_{JSD}—145—°CJunction temperature

Truth Table (per DC Motor Channel)

EN1A / 3A2A / 4A1Y / 3Y2Y / 4YMotor Direction
HIGHHIGHLOWHIGHLOWForward rotation
HIGHLOWHIGHLOWHIGHReverse rotation
HIGHLOWLOWLOWLOWFast motor brake
HIGHHIGHHIGHHIGHHIGHFast motor brake
LOWXXZZCoast (High-impedance)

Wiring

L293D Pin→Microcontroller / Motor / PowerNotes
VCC1 (Pin 16)5VLogic power supply
VCC2 (Pin 8)External Motor Power Supply (6V–36V)Dedicated high-current supply for motors
GND (Pins 4,5,12,13)Common GNDMust connect to MCU GND & Motor Power GND
1A, 2A (Pins 2, 7)Digital GPIO Pins (e.g. D4, D5)Direction control for Motor 1
1,2EN (Pin 1)PWM Pin (e.g. D3)Speed control via 0–2500 Hz PWM
1Y, 2Y (Pins 3, 6)Motor 1 TerminalsOutputs to DC Motor 1
Warning

High Internal Voltage Drop & Heat Generation: The L293D uses bipolar Darlington output transistors with a combined high/low side saturation voltage drop of ∼2.6 V\sim 2.6\text{ V}. When driving a 6V motor at 600 mA, nearly 1.5 W1.5\text{ W} is dissipated as heat inside the chip. Ensure center GND pins (pins 4, 5, 12, 13) are soldered to large PCB copper ground planes.

Common mistakes

  • Confusing L293 and L293D: The basic L293 (no "D") lacks internal flyback diodes. Using an L293 without external 1N4007 flyback diodes across the motor coils will destroy the chip. The L293D has integrated diodes.
  • Powering motors from VCC1 (5V logic rail): Inductive motor spikes and current draw cause voltage drops, resetting the MCU.
  • Ignoring 2.6V Darlington voltage drop: Supplying 6V to VCC2V_{CC2} only delivers ∼3.4 V\sim 3.4\text{ V} to the motor. For low-voltage motors (3V–6V), use a modern MOSFET driver like the TB6612FNG.

Notes

  • Pins 4, 5, 12, and 13 are internally connected together and serve as the main thermal heatsink path for the silicon die.

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