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DS1302数据手册datasheet
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2022-08-27
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DS1302数据手册datasheet
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REV: 072204
Note: Some revisions of this device may incorporate deviations from published specifications known as errata. Multiple revisions of any device
may be simultaneously available through various sales channels. For information about device errata, click here: www.maxim-ic.com/errata
.
FEATURES
§ Real-Time Clock Counts Seconds, Minutes,
Hours, Date of the Month, Month, Day of the
Week, and Year with Leap-Year Compensation
Valid Up to 2100
§ 31 x 8 RAM for Scratchpad Data Storage
§ Serial I/O for Minimum Pin Count
§ 2.0V to 5.5V Full Operation
§ Uses Less than 300nA at 2.0V
§ Single-Byte or Multiple-Byte (Burst Mode) Data
Transfer for Read or Write of Clock or RAM
Data
§ 8-Pin DIP or Optional 8-Pin SO for Surface
Mount
§ Simple 3-Wire Interface
§ TTL-Compatible (V
CC
= 5V)
§ Optional Industrial Temperature Range:
-40°C to +85°C
§ DS1202 Compatible
§ Underwriters Laboratory (UL) Recognized
PIN CONFIGURATIONS
ORDERING INFORMATION
PART TEMP RANGE PIN-PACKAGE TOP MARK
DS1302 0°C to +70°C 8 PDIP DS1302
DS1302N -40°C to +85°C 8 PDIP DS1302*
DS1302S 0°C to +70°C 8 SO (200 mils) DS1302S
DS1302SN -40°C to +85°C 8 SO DS1302S*
DS1302Z 0°C to +70°C 8 SO (150 mils) DS1302Z
DS1302Z+ 0°C to +70°C 8 SO (150 mils) + DS1302Z
DS1302ZN -40°C to +85°C 8 SO DS1302ZN
DS1302ZN+ -40°C to +85°C 8 SO + DS1302ZN
DS1302S-16 0°C to +70°C 16 SO (300 mils) DS1302S16
DS1302SN-16 -40°C to +85°C 16 SO (300 mils) DS1302SN16
*An N in the lower right-hand corner of the top mark denotes an industrial
part.
+ = lead-free device.
DETAILED DESCRIPTION
The DS1302 trickle-charge timekeeping chip contains a real-time clock/calendar and 31 bytes of static RAM. It
communicates with a microprocessor via a simple serial interface. The real-time clock/calendar provides seconds,
minutes, hours, day, date, month, and year information. The end of the month date is automatically adjusted for
months with fewer than 31 days, including corrections for leap year. The clock operates in either the 24-hour or
12-hour format with an AM/PM indicator.
DS1302
Trickle-Charge Timekeeping Chip
www.maxim-ic.com
V
CC1
SCLK
I/O
CE
V
CC2
X1
X2
GND
8
7
6
5
1
2
3
4
DIP (300 mils)
DS1302
V
CC2
X1
X2
GND
V
CC1
SCLK
I/O
CE
8
7
6
5
1
2
3
4
SO (200 mils/150 mils)
DS1302S/Z
V
CC2
X1
X2
GND
I/O
N.C.
N.C.
CE
8
7
6
5
1
2
3
4
SO (300 mils)
1
2
3
4
V
CC1
N.C.
SCLK
N.C.
8
7
6
5
N.C.
N.C.
N.C
N.C.
DS1302S
TOP VIEW
DS1302 Trickle-Charge Timekeeping Chip
2 of 13
Interfacing the DS1302 with a microprocessor is simplified by using synchronous serial communication. Only three
wires are required to communicate with the clock/RAM: CE, I/O (data line), and SCLK (serial clock). Data can be
transferred to and from the clock/RAM 1 byte at a time or in a burst of up to 31 bytes. The DS1302 is designed to
operate on very low power and retain data and clock information on less than 1mW.
The DS1302 is the successor to the DS1202. In addition to the basic timekeeping functions of the DS1202, the
DS1302 has the additional features of dual power pins for primary and backup power supplies, programmable
trickle charger for V
CC1
, and seven additional bytes of scratchpad memory.
OPERATION
Figure 1 shows the main elements of the serial timekeeper: shift register, control logic, oscillator, real-time clock,
and RAM.
TYPICAL OPERATING CIRCUIT
Figure 1. Block Diagram
POWER
CONTROL
v
CC1
v
CC 2
GND
INPUT
SHIFT
REGISTERS
I/O
SCLK
COMMAND AND
CONTROL LOGIC
REAL-TIME
CLOCK
31 x 8 RAM
OSCILLATOR
A
ND
COUNTDOWN
CHAIN
X1 X2
CE
1Hz
DS1302
DS1302
CPU
V
CC
V
CC2
SCLK
CE
GND
X2 X1
V
CC
I/O
V
CC1
DS1302 Trickle-Charge Timekeeping Chip
3 of 13
TYPICAL OPERATING CHARACTERISTICS
(V
CC
= 3.3V, T
A
= +25°C, unless otherwise noted.)
PIN DESCRIPTION
PIN
8 16
NAME FUNCTION
1 1 V
CC2
Primary Power-Supply Pin in Dual Supply Configuration. V
CC1
is connected to a
backup source to maintain the time and date in the absence of primary power. The
DS1302 operates from the larger of V
CC1
or V
CC2
. When V
CC2
is greater than V
CC1
+
0.2V, V
CC2
powers the DS1302. When V
CC2
is less than V
CC1
, V
CC1
powers the
DS1302.
2 3 X1
3 5 X2
Connections for Standard 32.768kHz Quartz Crystal. The internal oscillator is
designed for operation with a crystal having a specified load capacitance of 6pF.
For more information on crystal selection and crystal layout considerations, refer to
Application Note 58: Crystal Considerations for Dallas Real-Time Clocks. The
DS1302 can also be driven by an external 32.768kHz oscillator. In this
configuration, the X1 pin is connected to the external oscillator signal and the X2 pin
is floated.
4 8 GND Ground
5 9 CE
Input. CE signal must be asserted high during a read or a write. This pin has an
internal 40kW (typ) pulldown resistor to ground. Note: Previous data sheet revisions
referred to CE as
RST. The functionality of the pin has not changed.
6 12 I/O
Input/Push-Pull Output. The I/O pin is the bidirectional data pin for the 3-wire
interface. This pin has an internal 40kW (typ) pulldown resistor to ground.
7 14 SCLK
Input. SCLK is used to synchronize data movement on the serial interface. This pin
has an internal 40kW (typ) pulldown resistor to ground.
8 16 V
CC1
Low-Power Operation in Single Supply and Battery-Operated Systems and Low-
Power Battery Backup. In systems using the trickle charger, the rechargeable
energy source is connected to this pin. UL recognized to ensure against reverse
charging current when used with a lithium battery.
—
2, 4, 6,
7, 10,
11, 13,
15
N.C. No Connection
I
CC2T
vs. V
CC2T
5
10
15
20
25
30
2.0 3.0 4.0 5.0
V
CC2
(V)
SUPPLY CURRENT (uA
)
I
CC1T
vs. V
CC1T
100
150
200
250
300
350
400
2.0 3.0 4.0 5.0
V
CC1
(V)
SUPPLY CURRENT (nA
)
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