Ambiq Micro’s timing and power management semiconductors provide valuable features for applications implemented in physically small spaces with long-term operation using battery power or energy harvesting. Ambiq Micro integrates the features necessary to support these requirements in pin-compatible packages that optimize battery life and overall system power consumption. Our products, based on the SPOT platform, enable new applications for many different markets including powered smart cards, wireless sensors, battery operated consumer electronics, utility meters, security tokens and any application where product success or failure is measured in nanoamps.
VCC Power Switched
In this application type, the RTC uses an external transistor switch (T) to turn off power to the MCU. This implementation allows switching higher current and maintains a common ground. The value of (R) can be on the order of megohms, so that negligible current is drawn when the circuit is active and PSW/nIRQ2 is low.
In another implementation, the AM1800 RTC controls the system MCU using the reset function rather than switching power. Since many MCUs use much less power when reset, this implementation can save significant system power.
Battery Backed Up RTC
The most common AM0800 RTC application is a battery backed up real time clock, which maintains time and may hold data in on-chip RAM. The AM0800 is normally powered from a system power supply, which may even be a larger battery. The AM0800 RTC is continuously charging a supercapacitor or a small rechargeable battery via the built-in trickle charger. When the main power supply goes away, the AM0800 automatically switches to the VBAT supply and maintains time and on-chip RAM data at extremely low battery supply currents.
In many systems the main power supply is a battery, not wall power. The AM1800 RTC can minimize its current draw by powering down the MCU and other peripherals. The system battery/power supply may be replaced, and a supercapacitor charged via the AM1800 trickle charger can maintain system time and key parameters. Because the power requirements for the Ambiq Micro RTC is so low – (18nA in many cases) time and RAM data integrity can be kept for weeks and weeks from a small low cost supercapacitor.