DS1338U-3+ Maxim Integrated Products, DS1338U-3+ Datasheet - Page 11

• Manufacturer Part Number: DS1338U-3+
• Description: IC RTC 56BYTE NV RAM 3V 8-USOP
• Manufacturer: Maxim Integrated Products
• Type: Clock/Calendar/NVSRAMr

Specifications of DS1338U-3+

• Memory Size: 56B
• Time Format: HH:MM:SS (12/24 hr)
• Date Format: YY-MM-DD-dd
• Interface: I²C, 2-Wire Serial
• Voltage - Supply: 2.7 V ~ 3.3 V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 8-MSOP, Micro8™, 8-uMAX, 8-uSOP,
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

CONTROL REGISTER (07H)
The control register controls the operation of the SQW/OUT pin and provides oscillator status.
Bit 7: Output Control (OUT). Controls the output level of the SQW/OUT pin when the square-wave output is
disabled. If SQWE = 0, the logic level on the SQW/OUT pin is 1 if OUT = 1; it is 0 if OUT = 0.
Bit 5: Oscillator Stop Flag (OSF). A logic 1 in this bit indicates that the oscillator has stopped or was stopped for
some time period and can be used to judge the validity of the clock and calendar data. This bit is edge triggered,
and is set to logic 1 when the internal circuitry senses the oscillator has transitioned from a normal run state to a
STOP condition. The following are examples of conditions that may cause the OSF bit to be set:
This bit remains at logic 1 until written to logic 0. This bit can only be written to logic 0. Attempting to write OSF to
logic 1 leaves the value unchanged.
Bit 4: Square-Wave Enable (SQWE). When set to logic 1, this bit enables the oscillator output to operate with
either V
bits.
Bits 1 and 0: Rate Select (RS1 and RS0). These bits control the frequency of the square-wave output when the
square-wave output has been enabled. The table below lists the square-wave frequencies that can be selected
with the RS bits.
Square-Wave Output
Bit #
Name
POR
OUT
X
X
X
X
0
1
1) The first time power is applied.
2) The voltage present on V
3) The CH bit is set to 1, disabling the oscillator.
4) External influences on the crystal (i.e., noise, leakage, etc.).
CC
or V
RS1
X
X
0
0
1
1
BAT
BIT 7
OUT
applied. The frequency of the square-wave output depends upon the value of the RS0 and RS1
1
RS0
X
X
0
1
0
1
BIT 6
SQW OUTPUT
0
0
32.768kHz
4.096kHz
8.192kHz
CC
1Hz
and V
0
1
BAT
BIT 5
OSF
1
are insufficient to support oscillation.
SQWE
11 of 16
1
1
1
1
0
0
SQWE
BIT 4
1
BIT 3
0
0
DS1338 I
BIT 2
0
0
2
C RTC with 56-Byte NV RAM
BIT 1
RS1
1
BIT 0
RS0
1