Need help understanding the SN75441ONE/L293 QUADRUPLE HALF-H DRIVER ?

Hi all,

I don’t understand which voltage reference the PWM signal is taking from.

I saw online that i should connect the 5V from my arduino to pins 1,16 and 9. and on pin 8, i should connect a 5V supply with atleast 3A.

But if i send a pwn signal of saw 200 from the 0-255 pwm pin, seeing that my arduino 5v is really just 4.7V will the PWM signal map on this 4.7V or will it map on the 5.2V i get from the pin 8 ?

Attached is the spec sheet

Kind Regards

SN75441ONE SpecSheet.pdf (111 KB)

I don't understand which voltage reference the PWM signal is taking from.

Not sure that is a complete question but here goes.

You can drive the PWM signal to one of two places:- 1) The enable output, this will cause a free running stop to occur during the off time and is less effective in controlling the motor's speed, especially when the motor is lightly loaded. 2) Apply the PWM to one of the half H bridges. This causes fly wheel breaking to occur during the off time and so results in tighter control of a motor's speed, especially one with no load or a small load. The down side is that the speed control's direction is dependent on the motor's direction. In one direction the speed control is from 0 slowest to 255 fastest and in the other direction it is reversed.

Izzy92: But if i send a pwn signal of saw 200 from the 0-255 pwm pin, seeing that my arduino 5v is really just 4.7V will the PWM signal map on this 4.7V or will it map on the 5.2V i get from the pin 8 ?

You get the motor supply voltage less 1.5V due to it being a darlington driver. No point powering the motor side from such a low voltage, due to the 2.5 to 3V lost in the drivers.

The device is 4 switches, controlled by logic signal inputs. The fact the input signals are 5V (or 3.3V) has no effect on the behaviour, the switches are turned on and off.

The Darlington switches these chips use are inherently inefficient (fixed voltage loss), so better suited to 12V or 24V motors where the voltage loss is less significant.

MOSFET H-bridge chip will be much better for low voltage motors.