Pololu VNH2SP30 Driver for DC Motor Carrier MD01B

Overview

This module is a compact breakout board for ST’s high-power VNH2SP30 or VNH3SP30 motor driver IC, each of which is a fully integrated H-bridge that can be used for bidirectional speed control of a single brushed DC motor. The basic operation of the driver is summarized below, but we also recommend careful reading of the VNH2SP30 datasheet (670k pdf) or VNH3SP30 datasheet (586k pdf) before using this product. The board incorporates most of the components of the typical application diagram on page 8 of the VNH2SP30 datasheet, including pull-up and current-limiting resistors and a FET for reverse battery protection. It ships fully populated with its SMD components, including the VNH2SP30 or VNHSP30 motor driver IC, as shown in the product picture. (Note that the current sense circuit might not be populated on the VNH3SP30 version of the board since only the VNH2SP30 supports current sense.)

Note: Only the VNH2SP30 and VNH5019 support current sense; the current sense circuit might not be populated on the VNH3SP30 version of the board.

In a typical application, the motor power supply is connected at the bottom of the board, the motor on the right side of the board, and the control connections to the left side of the board. The diagnostic/enable pins are pulled high on the board and can be left disconnected if you do not want to monitor the fault conditions of the motor driver chip. INA and INB control the direction of the motor, and the PWM pin turns the motor outputs on or off, allowing you to control motor speed with a supplied pulse width modulation (PWM) signal. The PWM pin is pulled low on the board, so the motor driver outputs are effectively disabled by default; the INA and INB pins are floating (they are not pulled to any particular default voltage). See the truth tables in the VNH2SP30/VNH3SP30 datasheet for more information on how the INA, INB, and PWM pins affect the driver outputs, OUTA and OUTB.

For the VNH2SP30 version, the current sense (CS) pin will output approximately 0.13 volts per amp of output current. 

Schematic of the Pololu High Current Motor Driver Carrier

Warning: The top two mounting holes on this carrier board are electrically connected to the OUTA node in an effort to increase thermal dissipation. Please be aware of this if you are mounting more than one of these carrier boards to a metal structure using metal fasteners, or if you are mounting one of these carrier boards to a grounded structure using metal fasteners, as this could cause you to unintentionally short out your power supply. You can avoid the problem in such situations by avoiding those mounting holes or by using non-conducting mounting hardware, such as nylon screws.

Real-world power dissipation considerations

The motor drivers have maximum current ratings of 30 A continuous. However, the chips by themselves will overheat at lower currents (see table above for typical values). The actual current you can deliver will depend on how well you can keep the motor driver cool. The carrier printed circuit board is designed to draw heat out of the motor driver chips, but performance can be improved by adding a heat sink. In our tests, we were able to deliver short durations (on the order of milliseconds) of 30 A and several seconds of 20 A without overheating. At 6 A, the chip gets just barely noticeably warm to the touch. For high-current installations, the motor and power supply wires should also be soldered directly instead of going through the supplied terminal blocks, which are rated for up to 15 A.

This product can get hot enough to burn you long before the chip overheats. Take care when handling this product and other components connected to it.

Many motor controllers or speed controllers can have peak current ratings that are substantially higher than the continuous current rating; this is not the case with these motor drivers, which have a 30 A continuous rating and over-current protection that can kick in as low as 30 A (45 A typical). Therefore, the stall current of your motor should not be more than 30 A. (Even if you expect to run at a much lower average current, the motor can still draw short bursts of high currents, such as when it is starting, if special steps are not taken.)

Reverse-battery protection

The motor driver boards include an N-channel MOSFET for reverse-battery protection. This component keeps the motor driver from destroying itself if the input power is accidentally connected backwards. However, this component does slightly increase the total resistance between your battery and your motor. For slightly improved performance, the MOSFET can be bypassed by connecting the negative battery terminal to the bypass pin. (This terminal will also need to be connected to your logic supply ground.)

Specifications

Dimensions

General specifications

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