Is there 8V DC, 0.75A DC current limit IC?

[levnu]

is there IC in the market that can get input around 6Watt (8V DC, 0.75A DC) and output 8V DC 0.75A DC?

the thing is that i can provide only 8VDC and 0.75A DC and my Load tries to get around 1.2A thus my input voltage drops which i want to prevent

 

[picgak]

If your load will take 1.2A @ 8vDC , you cannot limit the current to.75A and maintain 8v
normally current is limitted by reducing the voltage in IC circuits

 

[levnu]

can't i sense the current and shunt it if it is above the 0.75A value?

 

[KonstanU]

Do you need output voltage 8V or it could be 4-6V? If it is so think about dc-dc converter.

 

[mtwieg]

is there IC in the market that can get input around 6Watt (8V DC, 0.75A DC) and output 8V DC 0.75A DC?

the thing is that i can provide only 8VDC and 0.75A DC and my Load tries to get around 1.2A thus my input voltage drops which i want to prevent

If the supply you're using is current limiting, then you have to increase the current limit, unless you can somehow reduce the peak current draw on the load (may or may not be possible).

In many SMPS controllers, both output current limit and output voltage are easily configured via resistor values.

 

[picgak]

Hi mtwieg,
His load consumes 1.2A @ 8vdc so how can you limit it to .75A still maintaining 8v

 

[levnu]

thanks for all replys,
can't i stabilize the output voltage by using e.g. boost or LDO & shunt the current from 1.2A to 0.75A ?

 

[bill66656]

Dear Levnu

What's your application, power source with over current protection or an 8V 0.75A charger?

For the former one, when the limit funtion is triggered, the output voltage will drop down, for the latter, that's the shunt structure and 0.75A is kept but VOUT is same as the charged object.


Good luck.

 

[levnu]

i'm trying to charge some aparatus but not with its official charger (Power supply) but with my limited home made charger that allows maximum 8V & 0.75A DC

its offical charger operation is:
@ no load output DC voltage to the load is 11.5V
@ 0.75A drawn current from the official power supply than the output of official charger drops to 8.3 V DC
@ 1A drawn current from the official PS than the output is of the offical power supply is even lower

but

when i provide 8V from a labratory power supply to the input of the aparatus instead of using the offical PS so the aparatus draws around 1.4A which i can not provide with my home made charger, so i need to put some current limiter at the output of my home made charger that will keep it with 8V DC and only 0.75A instead of 1.4A that the aparatus tries to achive.
is it possible to achive it? is it possible to have 8V output from boost and limit the output current to 0.75A instead of providing more and crashing my home made PS...

 

[bill66656]

Don't expect to see constant output voltage on output, but will see constant output current, for it's charger. The output will slope up according to the property of your “battery”. In one word, it's right to shunt it.

 

[picgak]

Hi Levnu,
If you use your lab supply 8v with the current limit circuit your problem will be surely solved.
You can even use 11.5V with a current limitting circuit set to .75A . Here you will see the voltage automatically varying to give the constant current

 

[levnu]

ok what i got now is:
When i fix my boost output voltage to 7.6V instead of 8V than the aparatus tries to get less current 0.7A (which i can provide) instead of the ~1.2A that drawn than 8V is applied to the input of the aparatus.
i hope it solving the problem and will allow me to charge the aparatus, yet i wonder how much slower it will be charged with 7.6V and 0.7A instead of 8V and ~1.2A
thank you all

 

[levnu]

sorry i'm coming back again its a lead acid battery that i try to charge

attached the battery i try to charge with an input of 7.2V from a boost and the current that drawn is not above 0.5A
do i harm to the battery by charging in this way or its just make the charging time longer? can i charge the battery at least to 90%?
the original power supply provides 8V 0.75A average charging
and
its say it needs to charge around 12 hours for 90-100%
i charged it for 15 hours with 7.2V and and fill it is near the 80% but i wonder if i do not make any harm to the battery

 

[picgak]

It is written on the battery that it should be charged at 20 Hr rate for optimum performance. So the required current is 225ma for 20 Hrs.Charging above 450ma current is not advisable. When you charged the battery if the temperature did not rise then the damage is minimal.