SM8578BV
Real-time Clock IC
OVERVIEW
The SM8578BV is a serial interface, real-time clock IC that uses a 32.768 kHz crystal oscillator for its refer-
ence timing. It comprises second-counter to year-counter clock and calendar circuits that feature automatic
leap-year adjustment, alarm and timer interrupt functions, as well as oscillator stop, timer reloading, and other
detection functions. Data is transferred to and from an external controller using a 3-wire serial interface. It is
available in compact 8-pin VSOP packages, making it ideal for use in all types of portable, hand-held equip-
ment.
FEATURES
I
I
PINOUT
(Top view)
I
I
I
I
I
I
I
I
I
1.6 to 5.5V wide operating voltage range
0.5µA (typ.) current consumption
(V
DD
= 3.0V, CE = Low)
3-wire serial interface control
Day, day-of-week, hour, and minute alarm inter-
rupt function
1/4096 seconds to 255 minutes presettable interval
timer interrupt function
Time update detection function
Abnormal oscillation detection function
Automatic leap-year adjustment function
(Western and Japanese calendars)
Oscillator capacitor C
D
built-in
Molybdenum-gate CMOS process
Miniature 8-pin VSOP package
INTN
XTN
XT
VSS
1
8
VDD
DATA
CLK
4
5
CE
ORDERING INFORMATION,
Device
SM8578BV
Package
8-pin VSOP
PACKAGE DIMENSIONS
(Unit: mm)
0 to 10°
4.4 ± 0.2
6.4 ± 0.3
0.585typ
1.15 ± 0.05
3.12 ± 0.3
+ 0.1
0.05
0.15
−
0.22 ± 0.1
NIPPON PRECISION CIRCUITS INC.—1
0.05 ± 0.05
0.65
1.30MAX
0.5 ± 0.2
NPC [ NIPPON PRECISION CIRCUITS INC ]
