I would like to power a circuit with 2 AA batteries for an input voltage range of about 1V-3V and an output of 3.3V to the circuit. I don't yet know what the current consumption would be but at this stage, I'm just trying to figure out how this particular IC works.
According to the datasheet,
9.1 Application Information
The TPS61322xx is designed to operates at a wide input voltage range from 0.9-V to 5.5-V. The minimum peak switch current limit is 0.5 A for TPS61322, with 0.75 A for TPS613221A and 1.1 A for TPS613222A.
Specifically for TPS613221A:
5 Device Comparison Table
PART NUMBER OUTPUT VOLTAGE TYPICAL CURRENT LIMIT TPS613221A 3.3V 1.2A
and
7.5 Electrical Characteristics
PARAMETER TEST CONDITIONS MIN TYP MAX UNIT ILIM Peak switch current limit TPS613221A 0.75 1.20 1.60 A
At this point, I'm still unclear what the maximum current that can be drawn by the circuit is and I don't see anything else in the datasheet related to maximum output current. I'm assuming it's the max peak switch current of 1.6A.
NOTE: There is also some information about high-output current with an external Schottky diode but this is specific to the TPS613222A (5V output) IC.
Now, if you head on over to the WEBENCH POWER DESIGNER website tool to configure the TPS613221A:
You can see that IOUT Max has a range from 0 to 0.7A. This range changes depending on the part number entered but doesn't correspond to any current limit on the datasheet. Moreover, if I increase the value to, say 0.2 for example, I get this error when I select the "view design" button:
Design cannot be created!
Your preferred device does not work with the inputs you selected.
If I select the default values and then try to change IOUT Max afterwards, I get this error:
Design update failed. The current limit of the part has been exceeded.
And just for reference, this is the circuit that was designed. It suggests using a 2.2uH inductor.
So here's what I'm trying to figure out:
- How can I figure out from the datasheet what the maximum current I can draw from a boost converter is? It doesn't seem to be as straightforward as reading off a value.
- Is peak switch current limit the same as this maximum current? Seems like this relates to the instantaneous switching currents.
- How does this differ from IOUT Max?
Thanks in advance!