Keep powering your system when the primary supply is intermittent: Page 3 of 6

April 12, 2019 //By Tony Armstrong and Steve Knoth
Keep powering your system when the primary supply is intermittent
In today’s world of constant connectivity, it is commonplace for many electronic systems to be always operational—regardless of their external environment or operating conditions. Said another way, any glitch in a system’s power supply, whether momentary, seconds, or even minutes, must be taken into account during its design process.

Batteries, on the other hand, can store a lot of energy, but are limited in terms of power density and delivery. Due to the chemical reactions that occur within a battery, they have limited life with regard to cycling. As a result, they are most effective when delivering modest amounts of power over a long period of time, since pulling many amps out of them very quickly severely limits their useful operating life. Table 1 shows a summary of the pros and cons among supercapacitors, capacitors, and batteries.


Table 1: Supercapacitor characteristics comparison vs. capacitors and batteries.

 

New backup manager power solutions

Now that we have established that either supercapacitors, batteries, and/or a combination of both are candidates for use as a backup power sources in almost any electronic system, what are some of the solutions available?

First of all, any IC solution would need to be a complete lithium ion battery backup power management system with the capability to keep 3.5 V to 5 V supply rails active during a main power failure event. Since batteries provide considerably more energy than supercapacitors, they are superior for applications that require backup for extended periods of time. Accordingly, any IC solution would need to have an on-chip bidirectional synchronous converter to provide high efficiency charging of the backup battery, as well as be able to deliver high current backup power to the downstream load should an interruption on the main power rail occur.

Design category: 

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