Max. current out of IC

Other Hardware General Electronics
1

Hi,

it has been a while, since I did this.
I have a shift register that switches Vout from 0 to 5V.
How can I derive the maximum output current? Idea: Put a 10nF cap on one of the pins, and measure the rise time. Could I translate this to an output current? How?

2

farsi:
How can I derive the maximum output current?

From the datasheets.

3

thanks, ah, remember again, the formula was: i = C*du/dt

4

farsi:
How can I derive the maximum output current? Idea: Put a 10nF cap on one of the pins, and measure the rise time.

Or....radical idea: Use a multimeter.

Both answers will be wrong though, anything you measure into a short circuit might damage the chip if you operate it at that current for longer periods of time..

Read the datasheet.

5

74HC595 - limit is 70mA, greater than you risk damaging the VCC and the Gnd wire.
Other chips - need a part number.

6

CrossRoads:
74HC595 - limit is 70mA, greater than you risk damaging the VCC and the Gnd wire.
Other chips - need a part number.

Limit per pin is much less than that.

(The true number is in the datasheet...)

7

Well, I did say the Vcc & Gnd pin ...

See page 6:
Only spec'ed to hold the outputs, 4.3V typical for a high and 0.17V typical for at low, at 6mA with Vcc = 4.5V. So maybe 4.8V with Vcc = 5V.