In order to avoid the difficulties involved with using PIC’s limited math capabilities to calculate the state of charge each time Vdd is measured, we created a lookup table that can be stored in the PIC’s program memory.
state of charge curve exhibited by Li-ion batteries when selecting the threshold voltages at which the microcontroller will display the color that corresponds to the battery’s state of charge (red, yellow, green, or blue). Wow the engineering world with your unique design: Design Ideas Submission GuideĪs with any state-of-charge gauge, this design must account for the non-linear voltage vs. The calculations for deriving the actual value of the sensed voltage from the A/D output are available in Microchip application note AN1072. As Vdd increases, the resulting number will decrease and vice versa, resulting in a “1/x” relationship between sensed voltage and the A/D’s output value. A measurement taken with the ADC, represents the 0.6V reference as a percentage of the voltage senses at the Vdd input. In this example, it is mounted inside the case of a Li-ion battery power bank where the PIC measures the battery’s voltage (sensed at its own Vdd pin) using its internal 0.6V band gap reference. The prototype board’s small size makes it easy to be added to existing products that currently lack a battery gauge.
【Download】Aprisa place-and-route tool for low-power SoCs The resulting solution can be implemented on a PCB as small as 3.1 × 3.2 mm 2 or easily integrated into an existing design ( Figure 1).įigure 1 A 1-dot bar graph display provides a compact and low-power alternative to the usual bar graph battery gauge. It consists of a surface-mount (SMD) style RGB LED, driven by an ultra-small-form-factor microcontroller, in this case, a Microchip PIC10F220 or PIC10F222 in a 6-pin package. This Design Idea is a 1-dot bar graph display that provides a simple, compact, low-cost, and low-power alternative to the usual four-LED bar graph battery gauge.
While most automotive, medical, and military applications require the functionality of a complete battery management system (BMS), many other products would be well-served by a much simpler battery gauge that simply tells the user how much charge is available to power the device. In particular, many applications could benefit from a cost-effective, but accurate battery charge gauge. With the rapid growth of embedded systems, and, in particular, IoT devices, there has been a growing need for improvements in the rechargeable battery systems that power them. This display uses a cheap six-pin microcontroller and a tri-color LED to realize a simple alternative to the usual four-LED bar graph battery gauge.
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