Sort by price and it's the cheapest RTC available. Microchip CEO Ganesh Moorthy on the golf course thinking he's beat everyone
I mention it as an example of Microchip rolling out shoddy product, and then not fixing the silicon after even 10 years. ACROSS THE BOARD MCP794xx, MCP795xx all are copy'n'paste same bugs i.e. "Date incrementing at noon" (plus rollovers) and then firmware hoops to workaround for the entire family. It's absurd they tested so poorly to begin with and continue selling them. But USD $0.59/100-lot and add $10 worth of hassle and $100 worth of headache some would say a bargain.
I don't use cheap RTC's anymore - either they drift too much or I've gotten burned with bugs in them.
Years ago it was PCF8583 that didn't reliably set the alarm flag, product stayed asleep and I had to helicopter out to sites $1,000/hr. Total nightmare.
It appears a maker favorite is the DS1307, but over 26 years old from the days of the 8051. But it's drifty and good luck fixing that with no tuning caps there. USD $3.13/100-lot.
I'm having success with the DS3231N but it's high cost is crazy - USD $8.70/100-lot. The MEMS version is lower cost DS3231M USD $7.33/100-lot.
Looking at an example of a newer part
MAX31329 USD $2.70/100-lot looks interesting but LGA-10 package, no trim, aging, drift spec etc. a dumbed down datasheet. It has internal xtal, battery trickle charge diodes/switches/resistors.
But who has time to mess around and try it? Nothing for how it performs over temperature.