Continue to Site

Welcome to EDAboard.com

Welcome to our site! EDAboard.com is an international Electronics Discussion Forum focused on EDA software, circuits, schematics, books, theory, papers, asic, pld, 8051, DSP, Network, RF, Analog Design, PCB, Service Manuals... and a whole lot more! To participate you need to register. Registration is free. Click here to register now.

Register Log in

Need clarification with the supply current to 74HC595!

Status
Not open for further replies.
V

Vijaykft

Newbie level 2
Joined
Feb 4, 2020
Messages
2
Helped
0
Reputation
0
Reaction score
0
Trophy points
1
Activity points
16
Hello everyone,
The deal is to compare the real time current rating of 74HC595 with its given rated value in the DATASHEET. So, we took input current reading several times through multimeter. Finally, it gives 1.32mA as input current whereas 70mA is the supply current given in the DATASHEET. But my doubt is that how the IC can get high with this lower current?. Please clear me why such differences in input current took place.
 

When it is driving high output currents into loads, the absolute maximum allowed Vcc or GND current is 70mA. The loads set the output currents and all the output currents are added together to make the 70mA allowed maximum.
The current into its inputs is almost nothing because it is Cmos. The Vcc and GND power supply current is not called the input current like you say.
 
Hi,

The measured current depends on a lot of things:
* where you measure the current (including or excluding load current)
* (load current)
* switching frequency
* temperature
* input voltage
* ...

Klaus
 

I have measured it with and also without load, but still it(74HC595) takes only 1.32mA.
 

Hi,

Read the post before: the supply current depends on a lot of things , not only on "load" .

"Only" 1.32mA is the wrong word, when expecting a max. quiescent supply current of 0.008mA (TI datasheet HC595).
(Mind the test conditions given in the datasheet)

Klaus
 

Status
Not open for further replies.

Similar threads

Part and Inventory Search

Welcome to EDABoard.com

Sponsor

Back
Top