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# INA330: INA330 Current limits

Part Number: INA330

Hello, I am using the INA330 for set-point temperature control application. I wanted to confirm a few aspects of my understanding of the datasheet.

Does the ±12.5uA maximum guaranteed current correspond to pin 7 (Io) or pin 8 (Vo)? This wasn't clear to me from the Current Conveyor - Current Output Range listed in the table on page 3 relative to the this statement on page 7: "The INA330 output (pin 8) is capable of swinging to within 10mV of the power-supply rails. It is able to achieve rail-to-rail output performance while sinking or sourcing 12.5μA." Similarly, is the Vo output current limit ±25mA (short circuit current)?

If the 12.5uA current limit does apply to the Io pin 7, I wanted to confirm that this inherently limits the Vo voltage swing based on the Rg value selected. The Vo swing would only guaranteed to be Rg*±12.5uA before Io becomes current-limited and the voltage won't scale linearly. So a 200k Rg gives a Vo=Vadj±2.5V, while a 5k Rg would give a Vo=Vadj±62.5mV. That voltage range could possibly be limited/saturated if the voltage swing extends too close to GND or V+ based on the Vadj set-point voltage. Is that all correct?

• Hi Scott,

pin 7 is the "CURRENT CONVEYOR" output and pin 8 is the "OUTPUT BUFFER" output. Page 3 has specifications for both, the "CURRENT CONVEYOR" and the "OUTPUT BUFFER". Don't confuse them.

Kai
• Hi Scott,

Kai is correct.

-Tamara
• Ok, thanks for the info Kai and Tamara. The table on page 3 is clear, it is just the (to me) contradictory statement on page 7 that I mentioned that had me questioning the data. That may want to be clarified in a future revision of the datasheet.

Based on the that info, can you also confirm the relationship between Rg and the voltage scale on Vo. Other posts on this forum suggested quite low values of Rg (~4k), which didn't make much sense to me because the Vo voltage (pre-output bufer) will be current-limited. See the 2nd part of my question in the original post.
• Hi Scott,

this need not to be a contradiction. With a 10k load at pin 8 the output voltage swing is 10mV from the rails typically. With a 100k load it is 5mV typically and with a load current of only up to +/-12.5µA the output is able to go even further to the rails.

As all example circuits given in the datasheet show the use of RG=200k I would not decrease this value, unless you want to decrease the output signal swing.

Kai
• Makes sense. Thank you for your help Kai.