Max outptu current of current monitor IC?

[Flyback]

Hello,
I am using ZXCT1009 to monitor current flow from a 3V battery.
What is the maximum voltage that Vout of zxct1009 can be?
(i.e. the voltage at the "iout" pin.)

I.e supposing current from the "iout" pin is 1mA...then how big can i make the output resistor?.....would 1K8 be ok? Whats the highest resistance it could be?

ZXCT1009 Datasheet
https://www.electro-tech-online.com/custompdfs/2013/06/ZXCT1009.pdf

 

[dougy83]

The datasheet says the device needs at least 2.5V, so no you can't use a 1k8 w/ 1mA on the IOUT leg.

 

[Flyback]

but 1K8 and 1mA gives just 1.8V...which is less than 2.5V...so it should be OK?

 

[dougy83]

but 1K8 and 1mA gives just 1.8V...which is less than 2.5V...so it should be OK?

No, it shouldn't. Voltage across the device is 3-1.8 = 1.2V

 

[Flyback]

Yes theres 1.2V between vsense and iout pins.
Does that matter?
Im not talking about the voltage across the sense resistor.

 

[ChrisP58]

2.5 volts is the minimum operating voltage of the ZXCT1009. And, since the '09 gets it's ground connection through the load resistor, it means that the minimum voltage between the +sense pin and the output pin, at any current, is 2.5V.

So, the highest output voltage that you can get with a 3V input is 0.5Volts.

 

[ronv]

If you look at the transfer characteristic curve you can see the max is almost a volt less than the power supply, which makes sense if you look at the little schematic of it in the example - it has an emitter follower output.

 

[blueroomelectronics]

Cool part, I like the PCB shunt resistor on page 6.

 

[Flyback]

So, the highest output voltage that you can get with a 3V input is 0.5Volts.

the max is almost a volt less than the power supply

....Which of these answers is correct?

 

[alec_t]

I'm guessing linearity could be poor if the chip doesn't get its full 2.5V; so I'd go for the 0.5V max out if Vin is 3V.

 

[ronv]

You know.. I don't know which is right. All I can do is tell you how I got there. I looked at the transfer curve. Lets say the lowest one - 2 ma. with .2 volts V sense. It looks like it needs 1.7 volts from Vin to Vout leaving 1.3 volts at 2 ma. or 650 ohms for the resistor. When I look at the top curve it looks like it takes 2.5 volts before it can deliver the full 10 ma. But I could also go for the 2.5 volts minimum but that would be kind of a wasted spec.