Device	Features	Supply voltage [V]*1	Time keeping current (typ)[µA]*2	Package	Datasheet
NR8576 series	Crystal oscillator element built-in Serial interface	2.5 to 5.5	1.0	SOP-14-101050-1	(96KB)
SM8577B	3-wire serial interface	2.5 to 5.5	1.0	SOP-8-052044-1	(96KB)
SM8578B	3-wire serial interface Alarm and timer interrupt functions	1.6 to 5.5	0.5	VSOP-8-031044-1	(113KB)
SM8580A	Temperature sensor built-in 4-bit parallel interface Alarm interrupt function	1.6 to 5.5	0.6	SSOP-24-100054-1	(167KB)

*1:It is specified only for clock and calendar operating voltage. Operating voltage for CPU access is specified by the other specification.
*2: It is specified for only when clock and calendar circuit operating. In this case accessing to CPU is not possible.