supply monitor with reset, and 512 bytes of EEPROM.
The clock provides hundredths of seconds, seconds,
minutes, and hours, and operates in 24-hour or 12-hour
format with an AM/PM indicator. The calendar provides
day, date, month, and year information. The date at the
end of the month is automatically adjusted for months
with fewer than 31 days, including corrections for leap
year. A watchdog timer provides a reset for an unre-
sponsive microprocessor. It is programmable in 10ms
intervals from 0.01 to 99.99 seconds. A temperature-
compensated voltage reference and comparator circuit
monitors the status of V
CC
. If a primary power failure is
detected, the device automatically switches to the
backup supply and drives the reset output to the active
state. The backup supply maintains time and date
operation in the absence of V
CC
. When V
CC
returns to
nominal levels, the reset is held low for a period to allow
the power supply and processor to stabilize. The
device also has a pushbutton reset controller, which
debounces a reset input signal. The device is
accessed through an I
2
C serial interface.
o
Fast (400kHz) I
2
C Interface
o
RTC Counts Hundredths of Seconds, Seconds,
Minutes, Hours, Day, Date, Month, and Year with
Leap Year Compensation Valid Up to 2100
o
Programmable Watchdog Timer
o
Automatic Power-Fail Detect and Switch Circuitry
o
Reset Output with Pushbutton Reset Input
Capability
o
512 x 8 Bits of EEPROM
o
Integrated Trickle-Charge Capability for Backup
Supply
o
Three Operating Voltages: 5.0V, 3.3V, and 3.0V
o
Low Timekeeping Voltage Down to 1.3V
o
-40°C to +85°C Temperature Range
o
UL Recognized
Features
Ordering Information
PART
DS1388Z-5+
DS1388Z-33+
DS1388Z-3+
TEMP RANGE PIN-PACKAGE
TOP
MARK
Applications
Portable Instruments
Point-of-Sale Equipment
Network Interface Cards
Wireless Equipment
-40°C to +85°C 8 SO (150 mils) DS1388-5
-40°C to +85°C 8 SO (150 mils) DS138833
-40°C to +85°C 8 SO (150 mils) DS1388-3
+Denotes
a lead(Pb)-free/RoHS-compliant package.
Pin Configuration
V
CC
Typical Operating Circuit
V
CC
CRYSTAL
V
CC
TOP VIEW
X1 1
X2 2
V
BACKUP
3
+
8
DS1388
7
6
5
V
CC
RPU
RST
SCL
SDA
SCL
CPU
SDA
DS1388
RST
V
BACKUP
RPU
X1
X2
V
CC
GND 4
SO
GND
RPU = t
R
/C
B
For pricing, delivery, and ordering information, please contact Maxim Direct at
1-888-629-4642, or visit Maxim Integrated’s website at www.maximintegrated.com.
19-4984; Rev 4 4/13
DS1388
I
2
C RTC/Supervisor with Trickle Charger
and 512 Bytes EEPROM
ABSOLUTE MAXIMUM RATINGS
Voltage Range on V
CC
or V
BACKUP
Pins
Relative to Ground.............................................-0.3V to +6.0V
Voltage Range on Inputs Relative
to Ground ...............................................-0.3V to (V
CC
+ 0.3V)
Junction-to-Ambient Thermal Resistance (θ
JA
) (Note 1)..170°C/W
Junction-to-Case Thermal Resistance (θ
JC
) (Note 1) ......40°C/W
Note 1:
Operating Temperature Range
(noncondensing) .............................................-40°C to +85°C
Storage Temperature Range .............................-55°C to +125°C
Lead Temperature (soldering, 10s) .................................+300°C
Soldering Temperature (reflow) .......................................+260°C
Package thermal resistances were obtained using the method described in JEDEC specification JESD51-7, using a four-layer
board. For detailed information on package thermal considerations, refer to
www.maximintegrated.com/thermal-tutorial.
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.
RECOMMENDED DC OPERATING CONDITIONS
(T
A
= -40°C to +85°C, unless otherwise noted.) (Note 2)
PARAMETER
Supply Voltage
SYMBOL
V
CC
(Note 3)
CONDITIONS
DS1388Z-5
DS1388Z-33
DS1388Z-3
Logic 1
Logic 0
Pullup Voltage (SCL, SDA),
V
CC
= 0V
V
BACKUP
Voltage
Power-Fail Voltage
V
IH
V
IL
V
PU
V
BACKUP
V
PF
(Note 3)
DS1388Z-5
(Note 3)
DS1388Z-33
DS1388Z-3
1.3
4.15
2.70
2.45
3.0
4.33
2.88
2.60
(Note 3)
(Note 3)
MIN
4.5
2.97
2.7
0.7 x
V
CC
-0.3
TYP
5
3.3
3
MAX
5.5
3.63
3.3
V
CC
+
0.3
+0.3 x
V
CC
5.5
5.5
4.50
2.97
2.70
V
V
V
V
V
V
UNITS
DC ELECTRICAL CHARACTERISTICS
(V
CC
= V
CC(MIN)
to V
CC(MAX)
, T
A
= -40°C to +85°C, unless otherwise noted.) (Note 2)
PARAMETER
Trickle-Charger Current-Limiting
Resistors
Input Leakage (SCL)
I/O Leakage (SDA)
I/O Leakage (RST)
SDA Logic 0 Output
(V
OL
= 0.15 x V
CC
)
SYMBOL
R1
R2
R3
I
LI
I
LO
I
LORST
I
OLDOUT
(Note 8)
(Notes 4, 5)
(Note 6)
(Note 7)
-1
-1
-200
CONDITIONS
MIN
TYP
250
2000
4000
+1
+1
+10
3
μA
μA
μA
mA
MAX
UNITS
2
Maxim Integrated
DS1388
I
2
C RTC/Supervisor with Trickle Charger
and 512 Bytes EEPROM
DC ELECTRICAL CHARACTERISTICS (continued)
(V
CC
= V
CC(MIN)
to V
CC(MAX)
, T
A
= -40°C to +85°C, unless otherwise noted.) (Note 2)
PARAMETER
RST
Logic 0 Output
SYMBOL
I
OLSIR
CONDITIONS
V
CC
> 2V; V
OL
= 0.4V
1.8V < V
CC
< 2V; V
OL
= 0.2 x V
CC
1.3V < V
CC
< 1.8V; V
OL
= 0.2 x V
CC
DS1388Z-5
V
CC
Active Current, EEPROM
2
Read, I C Read/Write Access
I
CCER
(Note 9)
DS1388Z-33
DS1388Z-3
DS1388Z-5
V
CC
Active Current, EEPROM
Write Cycle
I
CCEW
(Note 9)
DS1388Z-33
DS1388Z-3
DS1388Z-5
V
CC
Standby Current
I
CCS
(Note 10)
DS1388Z-33
DS1388Z-3
V
BACKUP
Leakage Current
(V
BACKUP
= 3.7V,
V
CC
= V
CC(MAX)
)
EEPROM Write/Erase Cycles
I
BACKUPLKG
T
A
= +25°C (guaranteed by design)
t
WR
T
A
= -40°C to +85°C (guaranteed by
design)
200k
50k
Cycles
15
100
MIN
TYP
MAX
3.0
3.0
250
600
250
225
1.0
0.70
0.65
270
150
140
100
nA
μA
mA
μA
UNITS
mA
μA
DC ELECTRICAL CHARACTERISTICS
(V
CC
= 0V,
V
BACKUP
= 3.7V, T
A
= +25°C, unless otherwise noted.) (Note 2)
PARAMETER
V
BACKUP
Current, OSC On
(EOSC = 0), SDA = SCL = 0V
V
BACKUP
Current, OSC Off
(EOSC = 1), SDA = SCL = 0V
(Data Retention)
SYMBOL
I
BACKUP
(Note 11)
CONDITIONS
MIN
TYP
410
MAX
550
UNITS
nA
I
BACKUPDR
(Note 11)
10
100
nA
Maxim Integrated
3
DS1388
I
2
C RTC/Supervisor with Trickle Charger
and 512 Bytes EEPROM
AC ELECTRICAL CHARACTERISTICS
(V
CC
= V
CC(MIN)
to V
CC(MAX)
, T
A
= -40°C to +85°C, unless otherwise noted.) (Note 2)
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