MD-000 Brushed DC motor driver

Overview

            This Brushed DC motor driver board utilizes Texas Instruments DRV8840 single IC H-bridge to give high performance with small size. The driver can be used with up to 45V DC supply, and deliver continuous 3.5 A (5 A Peak) current, while providing adjustable current limit. This driver also provided with high reliability protection.

            For easiness of use, some settable feature of DRV8840 has been set. The decay mode has been set to fast decay (coast), instead of slow decay (brake) often found in other driver. This driver can be driven in both sign-magnitude and locked anti-phase using 100 kHz PWM.

Feature

            Wide operating voltage: 8.2 V to 45 V.

            Output current: 3.5 A Continuous (5 A Peak).

            Adjustable current limit. Chopping at 50 kHz frequency.

            PWM Input up to 100 kHz (Both DIR and PWM pins).

            Operate in sign-magnitude and locked anti-phase modes.

            Compatible with 3.3 V and 5 V. No VCC require.

            Thermal Shutdown, automatically retry in 2 second.

            Shorted output protection.

Description

Pin out diagram

PIN	Description
VIN	Power supply positive, Absolute maximum is 45 V
GND	Power supply negative, Also connected with logic ground.
OUT A	Output A of H-Bridge. Connect this pin to terminal of DC motor.
OUT B	Output B of H-Bridge. Connect this pin to another terminal of DC motor.
WAKE	Logic input. When WAKE is high, driver will activate. When it is low, driver will deactivate.
DIR	Logic input. Controlling direction. Can be supplied with PWM Input.
PWM	Logic input. Controlling power rate. Can be supplied with PWM Input.
Current Limit	Adjustable current limit. Current limit = 0.0007143 x Resistance to ground. Maximum is 5 A. Current limiting is not precise as it is designed for safety only.

Caution

            The driver can operates without heat sink since it uses whole board as its heat sink, so It may hot enough to burn you before entering temperature shutting down.

Truth table

DIR	PWM	OUT A	OUT B
H	H	H	L
L	H	L	H
X	L	Fast Decay (Coasting, freewheeling)

            Different from other motor driver board, the decay mode is set to fast decay. When entering fast decay, the driver will switch into opposite direction to stop current flowing. After current reach zero, the bridge will be disabled. The driver will not enter brake mode, which two terminal of the motor are shorted together. More information can be read in DRV8840 datasheet.

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