| Schematics:
4A H bridge motor driver using the L298 IC
By Ibrahim Kamal
Last update:
28/02/08
 Brief Circuit explanation:
This is an implementation of the L298 to drive motors and
inductive loads up to 4A continuously. Initially the L298 contains
2 separate channels, each one capable of driving 2A loads. Connecting
them in parallel as in the schematic makes a single
4A driver.
The two wire connections W1 and W2 are to control the direction
of the motor according to that table:
Signal
on W1 and W2 |
result/action |
10 |
Motor turns clockwise |
01 |
Motor turns anticlockwise |
11 |
Motor breaks |
00 |
Motor is free |
The 2 transistors Q1 and Q2 act as an OR gate enabling the L298
if any of the two signals W1 or W2 are high. If both W1 and W2
are low (logic 0), the driver is disabled and provides a high
impedance on its output, causing an eventually connected motor
to move freely with its inertia.
C1 and C2 are 10 nF decoupling capacitors.
D1 to D4 are flyback diodes. Their forward current should correspond
with the the expected load.
The
two leads of the motor are directly connected to J1.
The circuit can be powered with 9 to 35V
Here is an implementation of this circuit on a PCB. This
an actual picture of the motor drivers we used in the ROBOCON
2007 competition.
Notice how the heatsink is firmly attached to the driver.
this protects the IC from eventually burning-up from stall
currents. |
|
Download
the zip file for this project
containing the full schematic, PCB designs and datasheet
of the L298 IC.
[note: i use ExpressPCB(FREEWARE)
to design the schematics and the PCB]
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Any questions? find
answers or ask your questions in ikalogic forum |
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