NPC SM8577BS Datasheet
SM8577B
NIPPON PRECISION CIRCUITS INC.
OVERVIEW
The SM8577B is a CMOS serial-interface type realtime clock IC that operates at 32.768 kHz. It
employs a 3-line serial interface to transfer time and
date data. It incorporates a supply-voltage detect
function to determine data validity/invalidity. It
features an output interrupt with 32 kHz or 1 Hz
output frequency. It is available in 8-pin SOPs.
FEATURES
■
2.5 to 5.5 V operating voltage range
■
1.0 µA at 3.0 V (typ) current consumption
■
3-line serial interface
■
1.7 ± 0.3 V supply voltage detection threshold
■
Timer counters for second, minute, hour, day, day
of the week, month, and year
■
Automatic leap-year calendar adjustment
■
32.768 kHz and 1 Hz output interrupt selectable
■
Crystal oscillator circuit built-in (C
■
24-hour time mode
■
8-pin SOP
built-in)
D
Real-time Clock IC
PINOUT
1
CE
DATA
CLK
FOUT
4
PACKAGE DIMENSIONS
Unit: mm
8-pin SOP
8577B
8
VDD
XTN
XT
5
VSS
+ 0.10
0.15
− 0.05
ORDERING INFOMATION
Device Package
SM8577BS 8pin SOP
1.27
5.2 0.3
0.4 0.1
4.4 0.2
6.2 0.3
1.5 0.1
0.05 0.05
4.4 0.2
0 to 10∞
NIPPON PRECISION CIRCUITS—1
≥
BLOCK DIAGRAM
SM8577B
VDD VSS
XT
OSC
Divider Timer Counter
XTN
FOUT
Output
Controller
Voltage
Detect
DATA
CLK
CE
I/O
Controller
PIN DESCRIPTION
Number Name I/O Description
1CEI
2 DATA I/O Data read and write input/output
3 CLK I
4 FOUT O
5 VSS – Ground
6 XT I Crystal oscillator element connection pin
7 XTN O Crystal oscillator element connection pin. Oscillator capacitor C
8 VDD –
Chip enable. With pull-down resistor built-in.
HIGH: Enable
LOW: DATA goes high impedance; input on CLK and DATA stops; and the TM bit is cleared.
Serial clock input.
Data is input (write mode) and output (read mode) on the rising edge of CLK.
Frequency output (controlled by the 4th data bit of the ‘week’ data, FSEL).
1 Hz output when FSEL is 0, and 32.768 kHz output when FSEL is 1.
In 1 Hz output mode, the 1 Hz signal is synchronized to the internal 1 second signal.
FOUT output is not affected by the CE signal.
Supply voltage.
Connect a
0.1 µF capacitor between VDD and VSS.
Shift Register
Controll
Circuit
is built-in.
D
NIPPON PRECISION CIRCUITS—2
−
−
−
SPECIFICATIONS
Absolute Maximum Ratings
V
= 0 V
SS
Parameter Symbol Condition Rating Unit
Supply voltage range V
Input voltage range V
Output voltage range V
Storage temperature range T
Power dissipation P
Soldering temperature T
Soldering time t
−
°
°
−
° C
−
ε
−
SM8577B
DD
IN
OUT
stg
D
sld
sld
0.3 to 7.0 V
V
0.3 to V
SS
V
0.3 to V
SS
+ 0.3 V
DD
+ 0.3 V
DD
55 to 125
150 mW
255
10 s
C
C
Recommended Operating Conditions
V
= 0 V
SS
Parameter Symbol Condition Rating Unit
Supply voltage range V
Operating temperature range T
DD
opr
Oscillator Characteristics
V
= 0 V, T
SS
noted
Oscillator start time t
Oscillator start voltage V
Oscillator stop voltage V
Frequency voltage characteristic f/V V
Frequency accuracy
Output capacitance C
= 25 ° C, C
a
= 12 pF, Seiko Epson C-002SH crystal (C
G
Parameter Symbol Condition
STA
STA
STO
D
V
DD
DD
V
DD
V
DD
2.5 to 5.5 V
40 to 85
= 30 k Ω , C
I
= 6 pF) unless otherwise
L
Rating
Unit
min typ m ax
= 2.5 V – – 3 s
1.5 – – V
– – 1.5 V
= 2.0 to 5.5 V
= 5.0 V
2 – +2 ppm/V
10 – +10 ppm
= 5.0 V – 12 – pF
NIPPON PRECISION CIRCUITS—3
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