SP6178 is a pulse width modulated output (PWM) DC buck converter that can drive 5A loads with high conversion efficiency. The input voltage range can be from 3.6V to 36V, the output voltage can be adjusted from 0.8V to 30V and the output current can be up to 5A. Using standard TO263-5L lead-free package, the application circuit is very simple and the peripheral devices are very few.
The rated voltage of the built-in (polymer lithium-ion) rechargeable battery is 3.7V, and it also needs to control the charging current and control the limiting voltage (4.2V), [the power management module plays this role when charging]. When discharging (charging the phone), the charging bank relies on a booster circuit and outputs a standard 5V voltage, which is also the role of the power management module.
on-off controller
Basically, it is a closed-loop feedback control system, which generally has a feedback output voltage sampling circuit and a feedback loop control circuit. Therefore, the design of this part is to ensure the accurate sampling circuit and control the feedback depth, because if the feedback loop response is too slow, it will have a lot of impact on the transient response ability.
The output part of the design includes the output capacitance, output inductance and MOSFET, etc. The selection of these components basically needs to meet a balance of performance and cost: high switching frequency can use a small inductance value, but higher switching frequency will increase interference and increase the switching loss of MOSFET, reducing the efficiency; Low switching frequencies have the opposite effect.