3.3v charge pump?

I was searching the web for components and came across this component called Mini 1.8V-5V to 3.3V Boost & Buck Low Noise Regulated Charge Pump. It was so tiny and seemed like a perfect alternative to the traditional joule thief. I looked for it's part number and found it's called LTC1517-3.3 and came with a diagram.

Do you think this circuit is good or efficient enough to drive a small 5mm 3.2V 20mA LED?

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That is neither a buck nor boost converter. It is a charge pump.

The output spec implies that it will just barely drive an LED, possibly not at the full 20mA. There are similar parts available with higher output current. You can get better results (at a cost of more external components) with a buck or boost converter.

Found another one that's capable of higher current loads. It's HX4002

Apparently it has an efficiency of less than 50% it seems.

Yeah, charge pumps have poor efficiency usually. Buck and boost converters can reach 90+% efficiency, charge pumps are generally under 50% - if you consider how it works, you can see that it's wasting a significant portion of the energy whenever it charges or discharges the cap, whereas the only losses on a buck/boost are from non-ideal behavior (diode drop, resistance of the inductor and switch, switching losses, etc).

Noobian:
It was so tiny and seemed like a perfect alternative to the traditional joule thief.

The "traditional Joule thief" circuit typically works at Vin down to about 0.7 V so will run off a single alkaline cell down to something approaching complete discharge. This thing won't even run off a single alkaline cell in prime condition.

That may or may not be important in a particular application, but if the requirement is simply to light a red LED with Vin down to 2 Volts, one doesn't really need a voltage converter.

MrMark:
The “traditional Joule thief” circuit typically works at Vin down to about 0.7 V so will run off a single alkaline cell down to something approaching complete discharge. This thing won’t even run off a single alkaline cell in prime condition.

That may or may not be important in a particular application, but if the requirement is simply to light a red LED with Vin down to 2 Volts, one doesn’t really need a voltage converter.

But if that’s used with 2x NiMh cells then it could damage the cells with such deep discharge.

They make boost converters that will run off a dying alkaline battery....

Yes, but I was looking for an alternative to YX8018 to power a white LED with two NiMh batteries. I don't want the converter to destroy my cells by draining too much. The YX8018 can do this with just one cell but when using two it will discharge too much.