To solve the charge management system
We have referred the factors to affect the battery charging. These are Input source, Output voltage regulation, Method of charging is completed and Battery temperature monitoring. Taking all these factors into account, we can develop an appropriate charge management system.
Linear solution, when the input source voltage is good, you can use the linear charging solutions. For example, Microchip’s MCP738xx linear battery charger series is a linear charging solution. In these applications, the linear solution provides many advantages, such as easy to use, small size and low cost.
Switch mode charging solutions, for a wide input voltage range, such as non-regulated AC-DC wall adapter, car DC input or a universal car adapter. Switching regulator battery charger can be reduced within a reasonable level of power loss.
Select the topology, switching regulator topology determines the switching regulator and passive filter components of the composition. The difference of this constitutes is following the choice of topology changes. And need to balance in the complexity, efficiency, noise and the trade-off between output voltage ranges. Power converter topologies have a lot. But only a few are for 5W ~ 50W range of battery chargers.
Buck regulator, buck regulator is a commonly used battery charging application topology. Buck regulator has the following advantages and disadvantages.
Disadvantages:
First, Integrated buck regulator diode in the MOSFET switch the input voltage will not constitute a battery discharge path. Require an additional blocking diode. Additional devices also cause the system to be additional pressure drop.
Second, buck regulator input current is pulsed, or intermittent. In this topology produces a high power input electromagnetic interference (EMI). Most regulators have a need for additional input EMI filter.
Third, step-down regulator can only compare the input voltage and low output voltage regulator. Some applications of the input voltage range, to cover the required output voltage range. For the multi-cell lithium ion battery cells charge the battery pack consisting of the application, this is very common.
Fourth, step-down switch short-circuit fault occurs when the short circuit between the input to the battery. Batteries do not have the internal protection of nickel-hydrogen batteries. It will lead to security problems.
Fifth, Buck regulators require high-end drive (for N-channel MOSFET switch), compared with the low-end topology, which will lead to the greater complexity.
Sixth, Pulse Width Modulation (PWM) controller applications external switch current sensing is more complex. For short-circuit or load short circuit failure mode, the switch current limit is very important. There is no high-speed switch current limit capability. The battery charger in the event of short circuit can be damaged.
The advantages are low complexity, single-inductor structure. For synchronous applications, the conversion efficiency is up to 90%. If you are considering whether it is suitable for your car, I recommend the universal car adapter to you. It is more convenient to carry.