SM8578BV
Real-time Clock IC
OVERVIEW
The SM8578BV is a serial interface, real-time clock IC that uses a 32.768kHz 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
0.575TYP
3.1 ± 0.3
+ 0.1
0.05
0.15
−
0.65
0.10
0.22 ± 0.1
0.1 ± 0.05
1.15 ± 0.05
0.12 M
SEIKO NPC CORPORATION —1
0.5 ± 0.2
SM8578BV
BLOCK DIAGRAM
VDD
VSS
Control Line
C
D
XTN
OSC
XT
Divider
Clock and Calendar
Register
Divider and
Timer Counter
OSC
Detect
Control Register
INTN
Interrupt and FOUT
Controller
Alarm Register
Shift Register
CLK
DATA
CE
Input
Controller
Control Circuit
Internal Bus
PIN DESCRIPTION
Number
1
2
3
4
5
6
Name
INTN
XTN
XT
VSS
CE
CLK
I/O
O
O
I
–
I
I
Function
Timer interrupt/alarm interrupt output, determined by internal mode setting, or frequency output, with
frequency value given in the frequency set register (N-channel open-drain output)
Oscillator output. Oscillator capacitor C
D
built-in.
Oscillator input
Negative supply voltage connection
Chip enable input with pull-down resistance built-in. Internal registers can be accessed when CE is HIGH.
Serial data transfer clock input.
In write mode, data is read in from DATA on the rising edge of CLK.
In read mode, data is read out from DATA on the rising edge of CLK.
Serial data transfer data input/output. When CE goes HIGH, the first four bits of write data determine the
operating mode (read mode/write mode).
Positive supply voltage connection. A 0.1µF bypass capacitor should be connected between VDD and VSS.
7
8
DATA
VDD
I/O
–
SEIKO NPC CORPORATION —2
SM8578BV
SPECIFICATIONS
Absolute Maximum Ratings
V
SS
= 0V
Parameter
Supply voltage range
Input voltage range
Output voltage range 1
Output voltage range 2
Power dissipation
Storage temperature range
Symbol
V
DD
V
IN
V
OUT1
V
OUT2
P
D
T
STG
Input pins
INTN
DATA
Condition
Rating
−0.3
to +7.0
V
SS
−
0.3 to V
DD
+ 0.3
V
SS
−
0.3 to +8.0
V
SS
−
0.3 to V
DD
+ 0.3
150
−55
to +125
Unit
V
V
V
V
mW
°C
Recommended Operating Conditions
V
SS
= 0V
Parameter
Supply voltage range
Operating temperature range
Symbol
V
DD
T
opr
Condition
Rating
1.6 to 5.5
−40
to +85
Unit
V
°C
DC Characteristics
V
SS
= 0V, V
DD
= 1.6 to 5.5V, C
G
= 10pF, Ta =
−40
to +85°C unless otherwise noted.
Rating
Parameter
Current consumption 1
Current consumption 2
HIGH-level input voltage
LOW-level input voltage
Input leakage current
Input resistance 1
Input resistance 2
Symbol
I
DD1
I
DD2
V
IH
V
IL
I
LEAK
R
DWN1
R
DWN2
V
OH1
Output voltage 1
V
OH2
V
OL1
V
OL2
Output voltage 2
V
OL3
V
OL4
Output leakage current
I
OZ
V
IN
= V
DD
or V
SS
, CE, CLK pins
V
DD
= 5V
V
DD
= 3V
V
DD
= 5V
V
DD
= 3V
V
DD
= 5V
V
DD
= 3V
V
DD
= 5V
V
DD
= 3V
V
IN
= V
DD
,
CE pin
I
OH
=
−1mA,
DATA pin
I
OL
= 1mA,
DATA pin
I
OL
= 1mA,
INTN pin
V
DD
= 5V
V
DD
= 3V
Condition
min
CE = V
SS
, DATA,
INTN = V
DD
–
–
0.8V
DD
0
−0.5
75
150
4.5
2.0
–
–
–
–
−0.5
typ
1.0
0.5
–
–
–
150
300
–
–
–
–
–
–
–
max
2.0
1.0
V
DD
0.2V
DD
0.5
300
600
5.0
3.0
V
SS
+ 0.5
V
SS
+ 0.8
V
SS
+ 0.25
V
SS
+ 0.4
0.5
µA
µA
V
V
µA
kΩ
kΩ
V
V
V
V
V
V
µA
Unit
CE, CLK, DATA pins
V
OUT
= V
DD
or V
SS
,
DATA, INTN pins
SEIKO NPC CORPORATION —3
SM8578BV
Oscillator Characteristics
Ta = 25°C, C
G
= 10pF, X’tal = NPC reference crystal (C
I
= 30kΩ, C
L
= 6pF) unless otherwise noted.
Rating
Parameter
Oscillator startup time
Oscillator stop voltage
Frequency voltage characteristic
Frequency accuracy
Output capacitance
Symbol
T
STA
V
STO
f/V
ε
IC
C
D
V
DD
= 1.6 to 5.5V
V
DD
= 5.0V
V
DD
= 5.0V
V
DD
= 1.6V
Condition
min
–
–
−2
−10
–
typ
–
–
–
–
15
max
5.0
1.5
2
10
–
s
V
ppm/V
ppm
pF
Unit
AC Characteristics
V
SS
= 0V, Ta =
−40
to +85°C unless otherwise noted.
Parameter
CLK clock cycle
CLK HIGH-level pulsewidth
CLK LOW-level pulsewidth
CE setup time
CE hold time
CE recovery time
CLK hold time
Write data setup time
Write data hold time
Read data output delay time
Output disable delay time
Input rise and fall time
Abnormal oscillation detection
time
Symbol
t
CLK
t
WH
t
WL
t
CS
t
CH
t
CR
t
CKH
t
DS
t
DH
t
RD
t
RZ
t
RF
t
OSC
C
L
= 50pF
C
L
= 50pF
R
L
= 10kΩ
Condition
min
600
300
300
150
200
300
50
50
50
–
–
–
10
V
DD
= 5.0V ± 10%
typ
–
–
–
–
–
–
–
–
–
–
–
–
–
max
–
–
–
–
–
–
–
–
–
200
100
20
–
min
1200
600
600
300
400
600
100
100
100
–
–
–
10
V
DD
= 3.0V ± 10%
typ
–
–
–
–
–
–
–
–
–
–
–
–
–
max
–
–
–
–
–
–
–
–
–
400
200
40
–
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ms
Unit
SEIKO NPC CORPORATION —4
SM8578BV
Timing Diagrams
t
CLK
t
CS
50%
t
WL
t
WH
t
CH
t
CKH
CLK
t
CR
CE
50%
Data write
CLK
50%
t
DH
DATA
50%
t
DS
CE
50%
t
CS
Data read
t
RF
t
RF
90%
CLK
50%
t
RD
10%
90%
DATA
50%
10%
t
RZ
Hi−Z
CE
50%
SEIKO NPC CORPORATION —5
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