Hello!
I'm having trouble deciding if I should use a charge pump for my project. I'm making an EMG front end circuit (See schematic attached) and used a charge pump (LM2776DBVR) and an LDO (TC593002ECBTR) to create a negative supply for the op-amps.
When I assembled the circuit though, it didn't really work as expected. Alone, the circuit created a -3.0 supply, but when it was connected to the op-amps the line was set to around 2.68 V. After playing around with the circuit for a bit, I got rid of the LDO, connected the charge pump directly to the op-amp supply line, and put a 100 ohm load in parallel.
The charge pump has a built in setting where if the current is less than 40 mA, it goes into a pulse skipping operation, so I'm guessing this was the issue.
Anyways, my question would be:
-would a different topology like a buck boost converter work better?
Adding the load in parallel causes the circuit to work but it's an extra 30 mA which is wasted as heat. Charge pumps definitely take up less space and are cheaper, but my end goal is to make some sort of wearable out of this, so having wasted power is not ideal.
Cheers
I'm having trouble deciding if I should use a charge pump for my project. I'm making an EMG front end circuit (See schematic attached) and used a charge pump (LM2776DBVR) and an LDO (TC593002ECBTR) to create a negative supply for the op-amps.
When I assembled the circuit though, it didn't really work as expected. Alone, the circuit created a -3.0 supply, but when it was connected to the op-amps the line was set to around 2.68 V. After playing around with the circuit for a bit, I got rid of the LDO, connected the charge pump directly to the op-amp supply line, and put a 100 ohm load in parallel.
The charge pump has a built in setting where if the current is less than 40 mA, it goes into a pulse skipping operation, so I'm guessing this was the issue.
Anyways, my question would be:
-would a different topology like a buck boost converter work better?
Adding the load in parallel causes the circuit to work but it's an extra 30 mA which is wasted as heat. Charge pumps definitely take up less space and are cheaper, but my end goal is to make some sort of wearable out of this, so having wasted power is not ideal.
Cheers
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