Need a little help on the behavior of an L293D h-bridge. It's to be used for a small robot. 2 channel variable PWM provided by a PIC12F509 in increments of 1% duty cycle @ 200HZ.
On the L293D when i apply 5vdc to Pin 2 (input-1) i get full voltage at Pin 3 (motor-1). This happens regardless of the state of the PWM input Pin 1 (Inhibit-1).
I have even physically removed the PIC from the circuit.
may be is fryed, but you can figure it out testing it , now, max. input voltage is 7 volts, I guess you did not over pass that? now, what did you connect to the output? you have 600 mili amps... and the enable is high right? I mean a secure high level not disconnected, you can connect it to 5 volts direct or to the enabling source...
try the table with 5 volts and find if is dead or not...
in enable out
H H H
L H L
H L Z
L L Z
The absolute max peak output current of an L293D is only 1.2A. The motor draws a very high current when it starts and when it is stalled. The over-current quickly melts an output transistor so it is on all the time.
Need a little help on the behavior of an L293D h-bridge. It's to be used for a small robot. 2 channel variable PWM provided by a PIC12F509 in increments of 1% duty cycle @ 200HZ.
On the L293D when i apply 5vdc to Pin 2 (input-1) i get full voltage at Pin 3 (motor-1). This happens regardless of the state of the PWM input Pin 1 (Inhibit-1).
I have even physically removed the PIC from the circuit.
it is fried, search no more. i had the exact same problem.
those litle motors in toy cars tend to drain a lot more current that you would execpt a motor of this size would.... i overcame this by providing very good heatsinking and ventilation..
The absolute max peak output current of an L293D is only 1.2A. The motor draws a very high current when it starts and when it is stalled. The over-current quickly melts an output transistor so it is on all the time.
I haven't looked at the datasheet but it's highly likely it can withstant a surge of at least 10 times that value for 50mS; it depends on the safe operating area of the transistor.
The L293D is made for driving tiny low power motors.
Its max continuous current is 600mA.
Its max peak current (for only 100us non-repetitive) is only 1.2A.
Hero, 50+% of the motors I own aren't capable of drawing 1.2AMPS stalled. Several of them would actually burst into flames if that much current was going through them even for a few ms's