Hello, I am using the IC SN74HC595 and I find with this problem. I connect led? in outputs and I have a consumption about 30mA, more or less, but if pin OE is high the outputs are disabled but the consumption is -10mA.
Why do I have this negative consumption?
Thanks,
Regards.
How are you wiring the LEDs?
It could be that you are back feeding the power pin with the shift register's inputs and causing current to flow out of the power pin. How are you measuring this?
Hello, thanks for reply.
I use this connections:
I connect a battery to SN74HC595 and short circuit battery-gnd with arduino-gnd. Then I connect the red tip of polimeter with vcc battery and the black tip with vcc of sn74hc595.
Then, the pin OE is connected to high and I measure -10mA. The program, in arduino, continues to run. I think the problem are the pins of control shift register are running.
I'll try to disconnect these pins and measure consumption.
Thanks,
Regards.
chstr:
I use this connections:
- gnd.- gnd
- vcc.- 3V3
I connect a battery to SN74HC595 and short circuit battery-gnd with arduino-gnd. Then I connect the red tip of polimeter with vcc battery and the black tip with vcc of sn74hc595.
It's hard to say where the reading is coming from but connecting 3v3 and battery VCC is a bad idea, even via a multimeter. You're short-circuiting a voltage regulator which has internal feedback, expect all sorts of oscillations as it tries to figure out what's going on.
- vcc.- 3V3
Is the Arduino running at 3V3?
If not and you continue to run 5V signals into the shift register then it is these signals that are parasitically sending current out of the power pin.
Hello, Vcc is connected to V+ of battery. I explained bad.
I solved the problem by cleaning the registry and cutting communication.
Thanks.
cleaning the registry
??
That is on a PC right? It has nothing to do with anything.