MX1508 dual motor driver

The small red module with two H bridges for two gear motors on one 2 V to 9.6 V supply, four inputs and a coast. Aliases: MX1508, MX-1508.

It is sold next to the L9110S board for the small two-wheel robot kits. Each motor has a pair of inputs; unlike the L9110S, both low lets the motor coast.

Pins

Pin	What it does
+, -	The supply for the chip and the motors, 2 V to 9.6 V.
IN1, IN2	Motor A's inputs.
IN3, IN4	Motor B's inputs.
MA1, MA2	Motor A (MOTOR-A).
MB1, MB2	Motor B (MOTOR-B).

The truth table

INA	INB	Motor
H	L	forward
L	H	reverse
L	L	coast (standby)
H	H	brake

While it runs

The face shows what each motor is being told: off, fwd, rev or brake.

What the model gets right

From the MX1508 datasheet:

The logic table. Input levels: a high is 2.0 V or more and a low 0.8 V or less, with a 12 kΩ pull-down on each, so a 3.3 V board drives it and an unwired pair coasts. On-resistance: 0.49 Ω a channel at 200 mA. The supply: off outside 2 V to 9.6 V (10 V is the absolute maximum). With a battery on + the bridges are part of the analog solve, so the pack sags under the motors.

What it does not model

The current ratings: about 1.35 A continuous a channel and 2 A peak (the sheet's overview says 1.5 A for one bridge and 0.8 A for the other), and the thermal shutdown. The chip's separate logic supply, which the module makes from +: the logic is taken as powered whenever + is in its band.

See it in action

MX1508 two-motor drive runs two gear motors off four AA cells from an Uno. Open it at /templates.