DS3234S# Maxim Integrated Products, DS3234S# Datasheet - Page 15

• Manufacturer Part Number: DS3234S#
• Description: IC RTC W/TCXO 20-SOIC
• Manufacturer: Maxim Integrated Products
• Type: Clock/Calendar/TCXO/Crystalr

Specifications of DS3234S#

• Memory Size: 2K (256 x 8)
• Time Format: HH:MM:SS (12/24 hr)
• Date Format: YY-MM-DD-dd
• Interface: SPI, 3-Wire Serial
• Voltage - Supply: 2 V ~ 5.5 V
• Operating Temperature: 0°C ~ 70°C
• Mounting Type: Surface Mount
• Package / Case: 20-SOIC (7.5mm Width)
• Function: Clock/Calendar/Alarm/Battery Backup/Interrupt
• Rtc Memory Size: 256 Byte
• Supply Voltage (max): 5.5 V
• Supply Voltage (min): 2 V
• Maximum Operating Temperature: + 70 C
• Minimum Operating Temperature: 0 C
• Mounting Style: SMD/SMT
• Rtc Bus Interface: Serial (4-Wire, SPI)
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

Bit 7: Oscillator Stop Flag (OSF). A logic 1 in this bit
indicates that the oscillator either is stopped or was
stopped for some period and may be used to judge the
validity of the timekeeping data. This bit is set to logic 1
any time that the oscillator stops. The following are
examples of conditions that can cause the OSF bit to
be set:
1) The first time power is applied.
2) The voltages present on both V
3) The EOSC bit is turned off in battery-backed mode.
4) External influences on the crystal (i.e., noise, leak-
This bit remains at logic 1 until written to logic 0.
Bit 6: Battery-Backed 32kHz Output (BB32kHz). This
bit enables the 32kHz output when powered from V
(provided EN32kHz is enabled). If BB32kHz = 0, the
32kHz output is low when the part is powered by V
This bit is enabled (logic 1) when power is first applied.
Bits 5 and 4: Conversion Rate (CRATE1 and
CRATE0). These two bits control the sample rate of the
TCXO. The sample rate determines how often the tem-
perature sensor makes a conversion and applies com-
pensation to the oscillator. Decreasing the sample rate
decreases the overall power consumption by decreas-
ing the frequency at which the temperature sensor
operates. However, significant temperature changes
that occur between samples may not be completely
compensated for, which reduce overall accuracy.
These bits are set to logic 0 when power is first applied.
* POR is defined as the first application of power to the device, either V
NAME:
POR*:
insufficient to support oscillation.
age, etc.).
CRATE1
0
0
1
1
Control/Status Register (0Fh/8Fh)
BIT 7
OSF
1
CRATE0
0
1
0
1
Extremely Accurate SPI Bus RTC with
BB32kHz
BIT 6
1
SAMPLE RATE
CC
____________________________________________________________________
(seconds)
CRATE1
BIT 5
and V
128
256
512
64
0
Integrated Crystal and SRAM
BAT
BAT
BAT
CRATE0
are
BIT 4
.
0
Bit 3: Enable 32kHz Output (EN32kHz). This bit indi-
cates the status of the 32kHz pin. When set to logic 1,
the 32kHz pin is enabled and outputs a 32.768kHz
square-wave signal. When set to logic 0, the 32kHz pin is
low. The initial power-up state of this bit is logic 1, and a
32.768kHz square-wave signal appears at the 32kHz pin
after a power source is applied to the DS3234. This bit is
enabled (logic 1) when power is first applied.
Bit 2: Busy (BSY). This bit indicates the device is busy
executing TCXO functions. It goes to logic 1 when the
conversion signal to the temperature sensor is asserted
and then is cleared when the conversion is complete.
Bit 1: Alarm 2 Flag (A2F). A logic 1 in the alarm 2 flag
bit indicates that the time matched the alarm 2 regis-
ters. If the A2IE bit and INTCN bit are set to logic 1, the
INT/SQW pin is driven low while A2F is active. A2F is
cleared when written to logic 0. This bit can only be
written to logic 0. Attempting to write to logic 1 leaves
the value unchanged.
Bit 0: Alarm 1 Flag (A1F). A logic 1 in the alarm 1 flag
bit indicates that the time matched the alarm 1 regis-
ters. If the A1IE bit and the INTCN bit are set to logic 1,
the INT/SQW pin is driven low while A1F is active. A1F
is cleared when written to logic 0. This bit can only be
written to logic 0. Attempting to write to logic 1 leaves
the value unchanged.
BAT
Control/Status Register (0Fh/8Fh)
EN32kHz
or V
BIT 3
CC
1
.
BIT 2
BSY
0
BIT 1
A2F
0
BIT 0
A1F
0
15