App note: How to shrink your USB Type-C battery charger


Maxim’s app note on a highly compact Type-C charger solution. Link here (PDF)

A highly integrated solution, as seen with the MAX77860 USB Type-C 3A switch-mode charger, dramatically reduces system complexity by integrating the charger, the power path, the Safeout LDO, ADC, and the USB-C CC and BC 1.2 detection in a small 3.9mm x 4.0mm, 0.4mm pitch, WLP package. OTG functionality is seamlessly integrated without the need for an extra inductor. This level of integration simplifies the design, enabling the delivery of more power and more functionality in minimal PCB space.

App note: Active cell balancing in battery packs


Cell balancing implementation from NXP Semiconductors. Link here (PDF)

Batteries made of multiple cells connected in series are often used as a power source for common electronic devices. In multicell battery chains, small differences between the cells (due to production tolerances or operating conditions) tend to be magnified with each charge or discharge cycle. In these situations, weaker cells are overstressed during charging, causing them to become even weaker, until they eventually fail and cause a premature failure of the whole battery. Cell balancing is a way of compensating for these weaker cells by equalizing the charge on all the cells in the chain, thus extending the battery life.

App note: Switching battery chargers


App note from Richtek about several aspects of switching chargers for single cell Li-Ion batteries. Link here (PDF)

Longer battery life and shorter charging times are some of the challenges in battery management in modern hand-held applications like Smart-Phones, Tablet PCs, POS and other portable equipment.

Devices with powerful processors are more power hungry and require larger capacity batteries to guarantee battery life. To quickly charge large capacity batteries, powerful high current chargers are needed. Linear chargers have too limited charge current capability for this purpose, so switching charger topology has to be adopted.

App note: High-speed lithium-ion battery charger


C8051F300 implementation of Li-Ion battery charger from Silicon Labs. Link here (PDF)

Driven by the need for untethered mobility and ease of use, many systems rely on rechargeable batteries as their primary power source. The battery charger is typically implemented using a fixedfunction IC to control the charging current/voltage profile.

The C8051F300 family provides a flexible alternative to fixed-function linear battery chargers. This note discusses how to use the C8051F300 device in Li-Ion battery charger applications. The Li-Ion charging algorithms can be easily adapted to other battery chemistries.

Solar battery charge controller teardown

A teardown video of a solar battery charge controller from Electronupdate:

A solar battery charger: one side goes to a Solar Panel, the other to a lead-acid battery. A charge controller allows the battery to be safely charged.
Snagged off of Amazon. Seemed really cheap at $17.36.
A look at the assembly quality tells me why. Bad soldering, mechanical errors, wrong wire sizes….
What is baffling, however, is that many of these workmanship issues (beyond the missing “fuse”) are just due to lack of attention… i.e. it would cost no more to do it right.

More info at Electronupdate blog.

Teardown of a Vivitar Rapid battery charger


Kerry Wong did a teardown of a Vivitar rapid battery charger for the NP-FW50 lithium-ion battery pack used in Sony A6000 digital camera:

The circuit board itself though looks surprisingly clean and well designed. It does not use any dedicated lithium ion battery charging ICs however. Rather a MC34063A buck/boost DC-DC converter chip is used to provide the current limited 8.4V constant voltage. This arrangement is less ideal then the typical lithium ion battery charging technique. Typically, the charging current is held constant until the voltage reaches a certain threshold and then the charger switches to constant voltage mode. Once the charging current drops under a predetermined threshold the charging is done. The charging current under constant voltage charging however, monotonically decreases from the get go so it usually takes much longer to obtain a full charge. But the good news here is that overcharging is unlikely as the charging voltage is fixed to the correct battery terminal voltage.

More details at Kerry Wong’s blog.

Check out the video after the break.

Capacitive battery charger


Marcus Jenkins made a capacitive battery charger using Dirty Board PCB’s to revive rechargeable batteries:

This is really a basic, bare-bones circuit. I’ve prepared the PCB with a view that it could be used as a module in a rather more-sophisticated charging system. You could imagine using a microcontroller (e.g. Arduino, PIC, etc.) to monitor the battery voltage and disconnect the mains input to the charger module when voltage reaches a user-selectable limit. The microcontroller could also have a thermistor probe to attach to the side of the battery with elastic – a basic precaution to try and automatically disconnect in the case unreasonable temperature rise while charging.

Project info at Marcus Jenkins’ blog.  You can order PCB’s for this project here.