MAX14870 Single DC Motor Driver Carrier 1.7A (2.5A peak)

Pololu MAX14870 Single DC Motor Driver Carrier 1.7A (2.5A peak)
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Price: £5.40
(£4.50 + VAT)
Availability: 34
Model: MAX14870
Manufacturer: Pololu
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Pololu

MAX14870 Single DC Motor Driver Carrier 1.7A (2.5A peak)

This compact breakout board for Maxim’s MAX14870 motor driver offers a wide operating voltage range of 4.5 V to 36 V and can deliver a continuous 1.7 A (2.5 A peak) to a single brushed DC motor. It features a simple two-pin speed/direction interface and built-in protection against reverse-voltage, under-voltage, over-current, and over-temperature.

The MAX14870 from Maxim Integrated is a tiny H-bridge motor driver IC that can be used for bidirectional control of one brushed DC motor at 4.5 V to 36 V. It can supply up to about 1.7 A continuously and can tolerate peak currents up to 2.5 A for a few seconds, making it a good choice for small motors that run on a wide range of voltages.

Features

  • Single-channel H-bridge motor driver with shoot-through protection and internal free-wheeling diodes (can drive one DC motor)
  • Motor supply voltage: 4.5 V to 36 V
  • Output current: up to 1.7 A continuous (2.5 A peak)
  • No separate logic supply needed; inputs are 3V- and 5V-compatible
  • simple two-pin DIR/PWM interface (one pin controls direction and another controls speed)
  • Under-voltage lockout on the logic supply and protection against over-current/short-circuit and over-temperature
  • Carrier board adds reverse-voltage protection
  • Active-low fault output indicates over-current or over-temperature condition
  • Surface-mount resistor can optionally be added to enable automatic current limiting
  • Compact size (0.6″×0.5″)

Using the motor driver

MAX14870 Motor Driver board connections

Motor and power connections are made on one side of the board and control connections are made on the other. The driver requires an operating voltage between 4.5 V and 36 V to be supplied to the reverse-protected power input, VIN. The VM pin provides convenient access to the reverse-protected supply voltage.

The MAX14870 offers a simple two-pin DIR/PWM control interface, where the DIR pin determines the motor direction and the PWM pin can be supplied with a PWM signal to control the motor speed. The PWM control input is pulled low on the carrier board through a 100 kΩ pull-down resistor. When the PWM pin is low, the motor outputs are both shorted to ground, which results in dynamic braking of a connected motor.

The EN pin can be driven high to turn off motor outputs, which is useful if you want to let the motor coast. The EN pin is pulled low through a 100 kΩ pull-up resistor on the carrier board so that the driver is enabled by default.

The following simplified truth table shows how the driver operates:

EN PWM DIR M1 M2 Operating Mode
1 X X high-impedance high-impedance coast (outputs floating/disconnected)
0 1 0 GND VIN “reverse”
0 1 1 VIN GND “forward”
0 0 X GND GND brake low (outputs shorted to ground)

Pinout

MAX14870 motor driver pinout

PIN Default State Description
VIN   Reverse-protected power supply input; supply this pin with 4.5 V to 36 V.
GND   Ground connection points for the power supply and control signals. The control source and the motor driver must share a common ground.
VM   This pin gives access to the motor power supply after the reverse-voltage protection MOSFET (see the board schematic below). It can be used to supply reverse-protected power to other components in the system. This net connects to the pin labeled “VDD” in the MAX14870 datasheet.
M1   H-bridge output 1.
M2   H-bridge output 2.
PWM LOW Speed control input; logic high causes the motor to drive.
DIR   Direction control input
FAULT FLOATING Open-drain, active-low fault output. This pin goes low during an over-current or over-temperature condition. You must use an external pull-up resistor to give this pin a default high value if you want to use it.
EN LOW Active-low enable input; drive high to tri-state the driver outputs.

Optional current limiting

The MAX14870 IC features a SNS input that can be used for optional automatic current limiting. By default, this input is connected to ground on the carrier board, which bypasses the current regulation feature. To enable current limiting, you must first cut the trace between the two unpopulated 1206 resistor pads on the top side of the carrier board:

MAX14870 current limiting

Then, you will need to add your own appropriate surface-mount 1206 resistor to these pads. An example of this is shown below:

MAX14870 current limiting

The driver tries to keep the voltage on the SNS pin from exceeding 100 mV, so for example, a 100 mΩ resistor limits the current to 1 A and a 200 mΩ resistor limits it to 0.5 A. For more information on current limiting refer to the datasheet.

Real-world power dissipation considerations

The MAX14870 datasheet recommends a maximum continuous current of 2.5 A. However, the chip by itself will typically overheat at lower currents. In our tests, we found that the chip was able to deliver 2.5 A for only a few seconds before the chip’s thermal protection kicked in and disabled the motor outputs; a continuous current of 1.7 A was sustainable for many minutes without triggering a thermal shutdown.

The actual current you can deliver will depend on how well you can keep the motor driver cool. The carrier’s printed circuit board is designed to help with this by drawing heat out of the motor driver chip. Our tests were conducted at 100% duty cycle with no forced air flow; PWMing the motor will introduce additional heating proportional to the frequency.

Documents

MAX14870 datasheet (492k pdf)

 

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MAX14870 Single DC Motor Driver Carrier 1.7A (2.5A peak)
Click to enlarge
MAX14870 Single DC Motor Driver Carrier 1.7A (2.5A peak)
Click to enlarge
MAX14870 Single DC Motor Driver Carrier 1.7A (2.5A peak)
Click to enlarge
MAX14870 Single DC Motor Driver Carrier 1.7A (2.5A peak)
Click to enlarge
MAX14870 Single DC Motor Driver Carrier 1.7A (2.5A peak)
Click to enlarge
MAX14870 Single DC Motor Driver Carrier 1.7A (2.5A peak)
Click to enlarge
MAX14870 Single DC Motor Driver Carrier 1.7A (2.5A peak)
Click to enlarge
MAX14870 Single DC Motor Driver Carrier 1.7A (2.5A peak)
Click to enlarge
MAX14870 Single DC Motor Driver Carrier 1.7A (2.5A peak)
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