NR8576 series
Real-time Clock Modules
OVERVIEW
The NR8576 series devices are serial-interface type real-time clock module ICs with built-in crystal oscillator
elements. They feature timer counter circuits that keep track of time from the current second to the current
year, automatic leap-year adjustment, and a supply voltage detect function. Also, a 32.768kHz/1Hz select out-
put function is incorporated for independent hardware control. They are available in compact 14-pin SOPs
(NR8576A×) and miniature 18-pin SOPs (NR8576B×).
FEATURES
I
I
I
I
Crystal oscillator element built-in for adjustment-
free use
Timer counters for second, minute, hour, day, day
of the week, month, and year
2.5 to 5.5V operating voltage range
1.7 ± 0.3V supply voltage detection threshold
I
I
I
I
1.0µA at 3.0V (typ) current consumption
Automatic leap-year calendar adjustment
32.768kHz and 1Hz output selectable
Package
• 14-pin SOP (NR8576A×)
• 18-pin SOP (NR8576B
×
)
PINOUTS
14-pin SOP
18-pin SOP
NC
1
2
3
4
5
6
7
8
9
18
17
16
15
14
13
12
11
10
NC
NC
NC
NC
VDD
NC
CLK
DATA
FOUT
VSS
NC
CE
FSEL
WR
FOE
NC
1
2
3
4
5
6
7
14
13
12
11
10
9
8
FOUT
NC
NC
DATA
CLK
VDD
NC
NC
NC
NC
FOE
WR
FSEL
CE
VSS
PACKAGE DIMENSIONS
(Unit: mm)
14-pin SOP
10.1 0.2
0 10
18-pin SOP
11.4 0.2
0 10
7.4 0.2
7.8 0.2
5.0
5.4
0.10 0.05
1.8 0.1
1.27
0.35 0.1
3.2 0.1
1.27
0.4 0.1
SERIES CONFIGURATION
Device
NR8576AA
NR8576AB
NR8576BA
NR8576BB
Package
14-pin SOP
14-pin SOP
18-pin SOP
18-pin SOP
Frequency deviation
5 ± 12 ppm
5 ± 23 ppm
5 ± 12 ppm
5 ± 23 ppm
SEIKO NPC CORPORATOIN—1
0.05 0.05
0.15
0.6 0.2
0.15
0.6 0.2
NR8576 series
BLOCK DIAGRAM
VDD
32.768kHz
VSS
OSC
FOUT
FSEL
FOE
DATA
CLK
WR
CE
Divider
Timer Counter
Output
Controller
Voltage
Detect
I/O
Controller
Shift Register
Control
Circuit
PIN DESCRIPTION
Name
VSS
I/O
–
Description
Ground
Connect a
≥
0.1µF capacitor between VDD and VSS.
Chip enable.
HIGH: Enable
LOW: DATA goes high impedance; input on WR, CLK, and DATA stops; and the TM bit is cleared.
FOUT output frequency select.
HIGH: 1Hz
LOW: 32.768kHz
DATA input/output control switch.
HIGH: Data input mode (RTC write)
LOW: Data output mode (RTC read)
FOUT output enable control.
HIGH: The frequency selected by FSEL is output on FOUT.
LOW: FOUT goes high impedance.
Supply voltage.
Connect a
≥
0.1µF capacitor between VDD and VSS.
System clock input.
Data is input (RTC write mode) and output (RTC read mode) on the rising edge of CLK.
Data read and write input/output
Frequency output (output controlled by FOE and frequency selected by FSEL).
In 1Hz output mode, the 1Hz signal is synchronized to the internal 1 second signal.
FOUT output is not affected by the CE signal.
No connection. Leave open for normal use.
CE
I
FSEL
I
WR
I
FOE
I
VDD
CLK
DATA
FOUT
NC
–
I
I/O
O
–
SEIKO NPC CORPORATOIN—2
NR8576 series
SPECIFICATIONS
Absolute Maximum Ratings
V
SS
= 0V unless otherwise noted.
Parameter
Supply voltage range
Input voltage range
Output voltage range
Storage temperature range
Symbol
V
DD
V
IN
V
OUT
T
STG
Condition
Ta = 25°C
Ta = 25°C
Ta = 25°C
Rating
−0.3
to 7.0
V
SS
−
0.3 to V
DD
+ 0.3
V
SS
−
0.3 to V
DD
+ 0.3
−55
to 125
Unit
V
V
V
°C
Recommended Operating Conditions
V
SS
= 0V unless otherwise noted.
Parameter
Supply voltage range
Clock supply voltage range
Operating temperature range
Symbol
V
DD
V
CLK
T
OPR
Condition
Rating
2.5 to 5.5
1.4 to 5.5
−40
to 85
Unit
V
V
°C
Oscillator Characteristics
V
SS
= 0V unless otherwise noted.
Parameter
Frequency deviation
Symbol
∆f/f
O
T
OP
f/V
t
STA
f
A
Condition
Ta = 25°C,
V
DD
= 5.0V
NR8576×A
NR8576×B
Rating
5 ± 12
5 ± 23
+10/−120
±2 max
3 max
±5 max
Unit
ppm
ppm
ppm
ppm/V
sec
ppm/year
Frequency temperature characteristic
Frequency voltage characteristic
Oscillator start time
Aging
Ta =
−10
to 70°C,
V
DD
= 5.0V, 25°C std
Ta = 25
°
C,
V
DD
= 2.0 to 5.5V
Ta = 25°C, V
DD
= 2.5V
Ta = 25°C, V
DD
= 5.0V,
first year
SEIKO NPC CORPORATOIN—3
NR8576 series
DC Electrical Characteristics
V
SS
= 0V, V
DD
= 5.0V ± 10%, Ta =
−40
to 85°C unless otherwise noted.
Rating
Parameter
Symbol
I
DD1
I
DD2
Current consumption
I
DD3
I
DD4
I
DD5
I
DD6
HIGH-level input voltage
LOW-level input voltage
Input OFF leakage current
V
IH
V
IL
I
OFF
V
OH1
V
OH2
LOW-level output voltage
Output load fanout
Output leakage current
Supply voltage detect
threshold voltage
V
OL1
V
OL2
N/CL
I
OZH
I
OZL
V
DT
V
DD
= 5.0V
V
DD
= 3.0V
V
DD
= 2.0V
V
DD
= 5.0V
V
DD
= 3.0V
V
DD
= 2.0V
Condition
min
CE = V
SS
, FOE = V
SS
,
FSEL = V
DD
,
FOUT: floating
–
–
–
–
–
–
0.8V
DD
–
–
4.5
2.0
–
–
typ
1.5
1.0
0.5
4.0
2.5
1.5
–
–
–
–
–
–
–
2 LSTTL/30pF max
−1.0
−1.0
1.4
–
–
1.7
1.0
1.0
2.0
µA
µA
V
max
3.0
2.0
1.0
10.0
6.5
4.0
–
0.2V
DD
0.5
–
–
0.5
0.8
µA
µA
µA
µA
µA
µA
V
V
µA
V
V
V
V
Unit
CE = V
SS
, FOE = V
DD
,
FSEL = V
SS
,
FOUT: 32kHz output
CE, FSEL, WR, FOE, CLK, DATA
CE, FSEL, WR, FOE, CLK, DATA
CE, FSEL, WR, FOE, CLK;
V
IN
= V
DD
or V
SS
V
DD
= 5.0V
V
DD
= 3.0V
V
DD
= 5.0V
V
DD
= 3.0V
FOUT
V
OUT
= 5.5V; DATA, FOUT
V
OUT
= 0V; DATA, FOUT
I
OH
=
−1.0mA;
DATA, FOUT
I
OL
= 1.0mA;
DATA, FOUT
HIGH-level output voltage
SEIKO NPC CORPORATOIN—4
NR8576 series
AC Characteristics
Ta =
−40
to 85°C, CL = 50pF unless otherwise noted.
Rating
Parameter
Symbol
V
DD
= 5V ± 10%
min
CLK clock period
CLK LOW-level pulsewidth
CLK HIGH-level pulsewidth
CE setup time
CE hold time
CE enable time
Write data setup time
Write data hold time
WR setup time
WR hold time
DATA output delay time
DATA output floating time
Clock rise time
Clock fall time
FOUT rise time (CL = 30pF)
FOUT fall time (CL = 30pF)
Disable time (CL = 30pF)
t
CLK
t
CLKL
t
CLKH
t
CES
t
CEH
t
CE
t
SD
t
HD
t
WRS
t
WRH
t
DATD
t
DZ
t
r1
t
f1
t
r2
t
f2
t
HZ
t
LZ
Enable time (CL = 30pF)
FOUT duty cycle (CL = 30pF)
Wait time
t
ZH
t
ZL
Duty
t
RCV
0.75
0.375
0.375
0.375
0.375
–
0.1
0.1
100
100
–
–
–
–
–
–
–
–
–
–
40
0.95
max
7800
3900
3900
3900
–
0.9
–
–
–
–
0.2
0.1
50
50
100
100
100
100
100
100
60
–
V
DD
= 3V ± 10%
min
1.5
0.75
0.75
0.75
0.75
–
0.2
0.1
100
100
–
–
–
–
–
–
–
–
–
–
40
1.9
max
7800
3900
3900
3900
–
0.9
–
–
–
–
0.4
0.2
100
100
200
200
200
200
200
200
60
–
µs
µs
µs
µs
µs
sec
µs
µs
ns
ns
µs
µs
ns
ns
ns
ns
ns
ns
ns
ns
%
µs
Unit
SEIKO NPC CORPORATOIN—5
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