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DS1340
User Manual
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MAXIM DS1340 User Manual

DS1340
I2C RTC with Trickle Charger
________________________________________________________________
Maxim Integrated Products
1
General Description
The DS1340 is a real-time clock (RTC)/calendar that is pin compatible and functionally equivalent to the ST M41T00, including the software clock calibration. The device additionally provides trickle-charge capability on the V
BACKUP
pin, a lower timekeeping voltage, and an oscillator STOP flag. Block access of the register map is identical to the ST device. Two additional regis­ters, which are accessed individually, are required for the trickle charger and flag. The clock/calendar pro­vides seconds, minutes, hours, day, date, month, and year information. A built-in power-sense circuit detects power failures and automatically switches to the back­up supply. Reads and writes are inhibited while the clock continues to run. The device is programmed seri­ally through an I2C bidirectional bus.
Applications
Portable Instruments
Point-of-Sale Equipment
Medical Equipment
Telecommunications
Features
♦ Enhanced Second Source for the ST M41T00 ♦ Available in a Surface-Mount Package with an
Integrated Crystal (DS1340C)
♦ Fast (400kHz) I2C Interface ♦ Software Clock Calibration ♦ RTC Counts Seconds, Minutes, Hours, Day, Date,
Month, and Year
♦ Automatic Power-Fail Detect and Switch Circuitry ♦ Trickle-Charge Capability ♦ Low Timekeeping Voltage Down to 1.3V ♦ Three Operating Voltage Ranges (1.8V, 3V, and 3.3V) ♦ Oscillator Stop Flag ♦ Available in 8-Pin µSOP or SO Packages ♦ Underwriters Laboratories (UL) Recognized
Ordering Information
4
CPU
V
CC
V
CC
V
CC
5
6
8
12
SDA
SCL
GND
X2X1
V
CC
C1
R
PU
R
PU
CRYSTAL
FT/OUT
V
BACKUP
3
7
R
PU
= tR / CB
DS1340
Typical Operating Circuit
PART TEMP RANGE
PIN­PACKAGE
TOP MARK
†
DS1340Z-18+ -40°C to +85°C
8 SO (0.150in)
D1340-18
DS1340Z-3+ -40°C to +85°C
8 SO (0.150in)
DS1340-3
DS1340Z-33+ -40°C to +85°C
8 SO (0.150in)
D134033
DS1340U-18+ -40°C to +85°C 8 μSOP 1340 -18
DS1340U-3+ -40°C to +85°C 8 μSOP 1340 -3
DS1340U-33+ -40°C to +85°C 8 μSOP 1340 -33
DS1340C-18# -40°C to +85°C 16 SO DS1340C-18
DS1340C-3# -40°C to +85°C 16 SO DS1340C-3
DS1340C-33# -40°C to +85°C 16 SO DS1340C-33
Pin Configurations appear at end of data sheet.
+
Denotes a lead(Pb)-free/RoHS-compliant package.
#
Denotes a RoHS-compliant device that may include lead(Pb) that is exempt under RoHS requirements. The lead finish is JESD97 category e3, and is compatible with both lead-based and lead-free soldering processes.
†
A "+" anywhere on the top mark denotes a lead(Pb)-free device.
A "#" denotes a RoHS-compliant device.
19-5578; Rev 7; 8/11
DS1340
I2C RTC with Trickle Charger
2 _______________________________________________________________________________________
ABSOLUTE MAXIMUM RATINGS
RECOMMENDED DC OPERATING CONDITIONS
(VCC= V
CC MIN
to V
CC MAX
, TA= -40°C to +85°C, unless otherwise noted. Typical values are at VCC= 3.3V, TA= +25°C, unless
otherwise noted.) (Note 1)
Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability.
Voltage Range on VCCPin Relative to Ground .....-0.3V to +6.0V
Voltage Range on SDA, SCL, and FT/OUT
Relative to Ground..................................-0.3V to (V
CC
+ 0.3V)
Operating Temperature Range ...........................-40°C to +85°C
Storage Temperature Range .............................-55°C to +125°C
Lead Temperature (soldering, 10s) .................................+260°C
Soldering Temperature (reflow) .......................................+260°C
Supply Voltage (Note 2) V
Input Logic 1 (SDA, SCL) VIH (Note 2) 0.7 x VCC V
Input Logic 0 (SDA, SCL) VIL (Note 2) -0.3 +0.3 x VCC V
Supply Voltage, Pullup (FT/OUT, SDA, SCL), V
Bac kup Supply Voltage (Note 2) V
Trickle-Charge Current-Limiting Resistors
Power-Fail Voltage (Note 2) V
Input Leakage (SCL, CLK) ILI -1 +1 μA
I/O Leakage (SDA, FT/OUT) ILO -1 +1 μA
SDA Logic 0 Output I
FT/OUT Logic 0 Output I
Active Supply Current (Note 7) I
Standby Current (Note 8) I
V
BACKUP
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
Lea kage Current I
DS1340-18 1.71 1.8 5.5
DS1340-3 2.7 3.0 5.5
DS1340-33 2.97 3.3 5.5
(Note 2) 5.5 V
DS1340-18 1.3 3.7
DS1340-3 1.3 3.7
DS1340-33 1.3 5.5
DS1340-18 1.51 1.6 1.71
DS1340-3 2.45 2.6 2.7
DS1340-33 2.70 2.88 2.97
VCC > 2V; VOL = 0.4V 3.0
1.7V < VCC < 2V; VOL = 0.2 x VCC 3.0
VCC > 2V; VOL = 0.4V 3.0
1.7V < VCC < 2V; VOL = 0.2 x VCC 3.0
1.3V < VCC < 1.7V; VOL = 0.2x VCC 250 μA
DS1340-18; VCC = 1.89V 72 150
DS1340-3; VCC = 3.3V 108 200
DS1340-33; VCC = 5.5V 192 300
DS1340-18; VCC = 1.89V 60 100
DS1340-3; VCC = 3.3V 81 125
DS1340-33; VCC = 5.5V 100 150
= 3.7V 100 nA
CC
= 0V
CC
V
PU
BACKUP
R1 (Notes 3, 4) 250
R2 (Note 5) 2000
R3 (Note 6) 4000
PF
OLSDA
OLSQW
CCA
CCS
BACKUPLKG VBACKUP
+ 0.3 V
CC
V
V
V
mA
mA
μA
μA
DS1340
I2C RTC with Trickle Charger
_______________________________________________________________________________________ 3
DC ELECTRICAL CHARACTERISTICS
(VCC= 0V, V
BACKUP
= 3.7V, TA= -40°C to +85°C, unless otherwise noted.) (Note 1)
AC ELECTRICAL CHARACTERISTICS
(VCC= V
CC MIN
to V
CC MAX
, TA= -40°C to +85°C, unless otherwise noted.) (Notes 1,14, Figure 1)
V
BACKUP
V
BACKUP
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
Current
Data-Retention Current I
I
BACKUP1
I
BACKUP2
I
BACKUP3
BACKUPDR
OSC ON, FT = 0 (Note 9) 800 1150
OSC ON, FT = 1 (Note 9) 850 1250
OSC ON, FT = 0, V
= +25°C (Notes 9, 10)
T
A
OSC OFF 25.0 100 nA
SCL Clock Frequenc y f
Bus Free Time Between STOP and START Condition s
Hold Time (Repeated) START Condition (Note 11)
Low Period of SCL Clock t
High Period of SCL Clock t
Data Hold Time (Notes 12, 13) t
Data Setup Time (Note 14) t
START Setup Time t
Rise T ime of SDA and SCL Signals (Note 15)
Fall Time of SDA and SCL Signals (Note 15)
Setup Time for STOP Condition t
Capacitive Load for Each Bus Line
I/O Capacitance (SCL, SDA) C
Pulse Width of Spikes that Must be Suppressed by the Input Filter
Oscillator Stop Flag (OSF) Delay t
PARAMETER SYMBOL CONDITIONS MIN TYP MA X UNITS
SCL
t
BUF
t
HD: STA
LOW
HIGH
HD:DAT
SU:DAT
SU:STA
t
R
t
SU:STO
C
I/O
t
SP
OSF
Standard mode 0 100
Fast mode 100 400
Standard mode 4.7
Fast mode 1.3
Standard mode 4.0
Fast mode 0.6
Standard mode 4.7
Fast mode 1.3
Standard mode 4.0
Fast mode 0.6
Standard mode 0 0.9
Fast mode 0 0.9
Standard mode 250
Fast mode 100
Standard mode 4.7
Fast mode 0.6
Standard mode 20 + 0.1CB 1000
Fast mode 20 + 0.1CB 300
Standard mode 20 + 0.1CB 300
F
Fast mode 20 + 0.1CB 300
Standard mode 4.7
Fast mode 0.6
(Note 15) 400 pF
B
10 pF
Fast mode 30 ns
(Note 16) 100 ms
BACKUP
= 3.0V,
nA
800 1000
kHz
μs
μs
μs
μs
μs
ns
μs
ns
ns
μs
DS1340
I2C RTC with Trickle Charger
4 _______________________________________________________________________________________
POWER-UP/POWER-DOWN CHARACTERISTICS
(TA= -40°C to +85°C) (Figure 2)
WARNING: Under no circumstances are negative undershoots, of any amplitude, allowed when device is in battery-backup mode.
Note 1: Limits at -40°C are guaranteed by design and not production tested. Note 2: All voltages are referenced to ground. Note 3: Measured at V
CC
= typ, V
BACKUP
= 0V, register 08h = A5h.
Note 4: The use of the 250Ω trickle-charge resistor is not allowed at V
CC
> 3.63V and should not be enabled.
Note 5: Measured at V
CC
= typ, V
BACKUP
= 0V, register 08h = A6h.
Note 6: Measured at V
CC
= typ, V
BACKUP
= 0V, register 08h = A7h.
Note 7: I
CCA
—SCL clocking at max frequency = 400kHz.
Note 8: Specified with I
2
C bus inactive.
Note 9: Measured with a 32.768kHz crystal attached to the X1 and X2 pins. Note 10: Limits at +25°C are guaranteed by design and not production tested. Note 11: After this period, the first clock pulse is generated. Note 12: A device must internally provide a hold time of at least 300ns for the SDA signal (referred to as the V
IH(MIN)
of the SCL
signal) to bridge the undefined region of the falling edge of SCL.
Note 13: The maximum t
HD:DAT
only has to be met if the device does not stretch the low period (t
LOW
) of the SCL signal.
Note 14: A fast-mode device can be used in a standard-mode system, but the requirement t
SU:DAT
≥ to 250ns must be met. This is automatically the case if the device does not stretch the low period of the SCL signal. If such a device does stretch the low period of the SCL signal, it must output the next data bit to the SDA line t
R MAX
+ t
SU:DAT
= 1000 + 250 = 1250ns
before the SCL line is released.
Note 15: C
B
—total capacitance of one bus line in pF.
Note 16: The parameter t
OSF
is the period of time the oscillator must be stopped for the OSF flag to be set over the 0V ≤ VCC≤
V
CCMAX
and 1.3V ≤ V
BAT
≤ 3.7V range.
Note 17: This delay applies only if the oscillator is enabled and running. If the oscillator is disabled or stopped, no power-up delay
occurs.
Figure 1. Data Transfer on I2C Serial Bus
Recovery at Power-Up t
VCC Fall Time; V V
PF(MIN)
VCC Rise Time; V V
PF(MAX)
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
REC
PF(MIN)
to
to
t
VCCF
t
VCCR
PF(MAX)
(Note 17) 2 ms
300 µs
0µs
SDA
t
BUF
t
LOW
SCL
t
HD:STA
STOP START REPEATED
NOTE: TIMING IS REFERENCED TO V
IL(MAX)
AND V
IH(MIN)
t
R
t
HD:DAT
.
t
HIGH
t
F
t
SU:DAT
START
t
SU:STA
t
HD:STA
t
SP
t
SU:STO
DS1340
I2C RTC with Trickle Charger
_______________________________________________________________________________________ 5
Figure 2. Power-Up/Power-Down Timing
Typical Operating Characteristics
(VCC= +3.3V, TA= +25°C, unless otherwise noted.)
I
CCSA
vs. VCC FT = 0
DS1340 toc01
VCC (V)
SUPPLY CURRENT (μA)
5.04.54.03.53.02.52.01.5
50
100
150
200
250
0
1.0 5.5
25
50
75
100
125
150
0
I
CCS
vs. VCC FT = 0
DS1340 toc02
VCC (V)
SUPPLY CURRENT (μA)
5.04.54.03.53.02.52.01.51.0 5.5
-1.8V
-3.0V
-3.3V
I
BACKUP1
(FT = 0) vs. V
BACKUP
DS1340 toc03
450
500
550
600
650
700
750
800
850
400
V
BACKUP
(V)
SUPPLY CURRENT (nA)
5.04.54.03.53.02.52.01.51.0 5.5
I
BACKUP2
(FT = 1) vs. V
BACKUP
DS1340 toc04
450
500
550
600
650
700
750
800
850
400
V
BACKUP
(V)
SUPPLY CURRENT (nA)
5.04.54.03.53.02.52.01.51.0 5.5
I
BACKUP3
vs. TEMPERATURE
DS1340 toc05
TEMPERATURE (°C)
SUPPLY CURRENT (nA)
6040-20 0 20
500
550
600
650
700
750
800
850
-40 80
V
BACKUP
= 3.0V
OSCILLATOR FREQUENCY vs. SUPPLY VOLTAGE
(FT x 64)
DS1340 toc06
V
BACKUP
(V)
FREQUENCY (Hz)
5.04.54.03.53.02.52.01.5
32768.1
32768.2
32768.3
32768.4
32768.5
32768.6
32768.0
1.0 5.5
V
CC
V
V
INPUTS
OUTPUTS
PF(MAX)
PF(MIN)
RECOGNIZED RECOGNIZED
VALID
V
t
F
PF
DON'T CARE
HIGH-Z
V
PF
t
R
t
REC
VALID
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