Hi,
I'd be surprised.
Usualy they have a USB connector, thus I assume the output voltage needs to be regulated to keep on USB supply standards.
Otherwise one risks overvoltage and damage of a USB device connected to the power bank...or undervoltage causing malfunction.
But I don't know for sure.
Klaus
Agreed, I do know that all phones contain some sort of buck-boost converter but I'm not sure if that also extends towards the charging port as a secondary protection feature.
requirements is that the output should be 5v at 1000mA and has an LCD that shows percentage.The schematics I found online are made of 2 parts and I didn't understand them as there is no connection and there is some missing things as I want to make a simulation for the circuit on Proteus I circled what I can't understand,and if you know please give me some clues and after printing the design what should I connect in these nodes ?
Thanks in advance
View attachment 155268
1. The top part of the schematic has a TP4058 linear battery charge controller, so it is obviously meant for charging the bank's cells in a controlled manner. The bottom part of the schematic has a XL6009 boost converter to step-up voltage, so it is obviously meant for discharging the bank's cells (and charging other devices). I assume whoever designed the circuit did it in a modular manner instead of creating a convoluted mess of a circuit.
2. Although there are no "visible" wire connections from one point to another, it doesn't mean that the circuit design is faulty or incomplete. I'm not exactly sure what the proper term is for those input/output ports (or terminals, however it's called), but their function is to act as an "invisible" wire connection from one point in the circuit to another. This function is identified as hierarchical ports in PSpice (PORTLEFT/PORTRIGHT), and INPUT/OUTPUT terminals in Proteus.
Since you referred the schematic from a different source, I'll leave it to you on figuring out where the connections go. If the person who designed the schematic wrote in detail about how the entire circuit works, then you can analyse and extract the important data from the description and finish up the connections by yourself.
opcorn:
EDIT: Since the schematic you showed only has two LEDs for showing the powerbank charge status, you will need a LCD display driver. You can use a charge controller + LCD display driver such as a LDR5409 (datasheet is in Chinese only), or you can use individual ICs for both functions.