Basic problems with a ULN2803A

[Conrad, Robert]

I setup my ULN2803A on a bread board with Ground grounded, and Common
powered to 9V. When ever I wire pin 1 to a 5V source I am getting .653V on
the output (pin 18) same with all the other pins. I can not get the chip to
provide any more voltage than that. What could be the cause of this?

 

[hamilton]

Ugh,

Do you have the data sheet ???

<http://focus.ti.com/lit/ds/symlink/uln2803a.pdf>

Hint: page 2, lower drawing.......

Conrad, Robert wrote:

I setup my ULN2803A on a bread board with Ground grounded, and Common
powered to 9V. When ever I wire pin 1 to a 5V source I am getting .653V on
the output (pin 18) same with all the other pins. I can not get the chip to
provide any more voltage than that. What could be the cause of this?

 

[Conrad, Robert]

Okay, so Im an idiot.. like 5 minutes after posting that I realized that I
was misunderstanding what I should be expecting to see. (I assumed that in
the off state the output would be roughly common voltage (so the voltage
across the load would be 0V)

Though, what second drawing? My book has the pinout and then the electrical
characteristics chart.


"hamilton" <hamilton@deminsional.com> wrote in message
news:40062c81_1@omega.dimensional.com...

Ugh,

Do you have the data sheet ???

http://focus.ti.com/lit/ds/symlink/uln2803a.pdf

Hint: page 2, lower drawing.......

Conrad, Robert wrote:
I setup my ULN2803A on a bread board with Ground grounded, and Common
powered to 9V. When ever I wire pin 1 to a 5V source I am getting .653V
on
the output (pin 18) same with all the other pins. I can not get the chip
to
provide any more voltage than that. What could be the cause of this?

 

[hamilton]

Well you did not post your data sheet, so I posted one for everyone to see.

So, in this data sheet I posted, page 2 lower drawing shows an open
collector circuit ( this is the point). Also shown in this schematic is
a doide connect to all 8 open collectors in the package. This diode is
for the flyback effect of relays. I am sure others here can find other
uses for this diode.

Conrad, Robert wrote:

Okay, so Im an idiot.. like 5 minutes after posting that I realized that I
was misunderstanding what I should be expecting to see. (I assumed that in
the off state the output would be roughly common voltage (so the voltage
across the load would be 0V)

Though, what second drawing? My book has the pinout and then the electrical
characteristics chart.


"hamilton" <hamilton@deminsional.com> wrote in message
news:40062c81_1@omega.dimensional.com...

Ugh,

Do you have the data sheet ???

http://focus.ti.com/lit/ds/symlink/uln2803a.pdf

Hint: page 2, lower drawing.......

Conrad, Robert wrote:

I setup my ULN2803A on a bread board with Ground grounded, and Common
powered to 9V. When ever I wire pin 1 to a 5V source I am getting .653V

on

the output (pin 18) same with all the other pins. I can not get the chip

to

provide any more voltage than that. What could be the cause of this?