I have a circuit where I need to invert two 3.3V - 0V 'Active Low' signals on a 3.3V rail to two switching transistors on the 5Vss rail to switch a < 200mA load (8 LED's).
I have designed and tested a circuit on a breadboard using a BC557 and BC548 per signal but would much prefer to use a DIP package to do the same thing.
Currently, my circuit simply switches the BC557 on across the 3.3V rail when the signal goes from 3.3V to 0V, and supplies a collector current to the base of BC548, switching it on and driving the LED's.
Can anyone suggest;
1/ a quad NPN - PNP complimemtary pair that would replace the BC557 and transistor to switch around 120mA - 160mA?
or
2/ a better way
Keep in mind the following:
The signal is active low.
The device is plugged into USB, and as such must not turn the outputs on when the computer shuts down and leaves 5Vss on the USB port.
The 3.3V Rail goes to 0V when the USB is 'deactivated'.
Space is a bit limited so I'd like to keep my component count to a minimum.
TIA for any advice or suggestions.
Mat
I have designed and tested a circuit on a breadboard using a BC557 and BC548 per signal but would much prefer to use a DIP package to do the same thing.
Currently, my circuit simply switches the BC557 on across the 3.3V rail when the signal goes from 3.3V to 0V, and supplies a collector current to the base of BC548, switching it on and driving the LED's.
Can anyone suggest;
1/ a quad NPN - PNP complimemtary pair that would replace the BC557 and transistor to switch around 120mA - 160mA?
or
2/ a better way
Keep in mind the following:
The signal is active low.
The device is plugged into USB, and as such must not turn the outputs on when the computer shuts down and leaves 5Vss on the USB port.
The 3.3V Rail goes to 0V when the USB is 'deactivated'.
Space is a bit limited so I'd like to keep my component count to a minimum.
TIA for any advice or suggestions.
Mat
