DS32C35-33IND# Maxim Integrated Products, DS32C35-33IND# Datasheet - Page 10

• Manufacturer Part Number: DS32C35-33IND#
• Description: IC RTC W/TCXO 20-SOIC
• Manufacturer: Maxim Integrated Products
• Type: Clock/Calendar/TCXO/Crystal/FRAMr

Specifications of DS32C35-33IND#

• Memory Size: 64K (8K x 8)
• Time Format: HH:MM:SS (12/24 hr)
• Date Format: YY-MM-DD-dd
• Interface: I²C, 2-Wire Serial
• Voltage - Supply: 2.7 V ~ 3.63 V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 20-SOIC (7.5mm Width)
• Function: Clock/Calendar
• Rtc Memory Size: 8192 B
• Supply Voltage (max): 3.63 V
• Supply Voltage (min): 2.7 V
• Maximum Operating Temperature: + 85 C
• Minimum Operating Temperature: - 40 C
• Mounting Style: SMD/SMT
• Rtc Bus Interface: I2C
• Supply Current: 260 uA
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

Accurate I
TCXO/Crystal/FRAM
The Block Diagram shows the main elements of the
DS32B35/DS32C35. The nine blocks can be grouped
into six functional groups: TCXO, power control, pushbut-
ton function, RTC, I
tions are described separately in the following sections.
The temperature sensor, oscillator, and control logic
form the TCXO. The controller reads the output of the
on-chip temperature sensor and uses a lookup table to
determine the capacitance required, adds the aging
correction in the AGE register, and then sets the
capacitance selection registers. New values, including
changes to the AGE register, are loaded only when a
change in the temperature value occurs, or when a
user-initiated temperature conversion is completed.
The temperature is read on initial application of V
and once every 64 seconds afterwards while the
device is powered by either V
This function is provided by a temperature-compensat-
ed voltage reference and a comparator circuit that
monitors the V
the part is powered by V
but greater than V
V
is powered by V
The RTC can be accessed when the device is powered
by either V
when the device is powered by V
not be accessed when V
To preserve the battery, the first time V
the device, the oscillator will not start up until V
exceeds V
the part. Typical oscillator startup time is less than one
second. Approximately 2 seconds after V
or a valid I
temperature measurement and applies the calculated
Table 1. Device Operation
* Read/write access is not inhibited by the device, but must not
be done to avoid FRAM data errors.
10
V
V
V
V
CC
SUPPLY CONDITION
CC
CC
CC
CC
is less than V
< V
< V
> V
> V
____________________________________________________________________
PF
PF
PF
PF
, V
, V
, V
, V
PF
CC
2
CC
CC
CC
CC
C address is written, the device makes a
, or until a valid I
CC
< V
> V
< V
> V
or V
BAT
BAT
BAT
BAT
BAT
level. When V
PF
2
BAT
BAT
. See Table 1.
C interface, and FRAM. Their opera-
and is less than V
, the RTC is powered by V
. The FRAM is only accessible
POWERED
CC
CC
2
V
V
V
V
. When V
BY
BAT
< V
C RTC with Integrated
CC
CC
CC
CC
2
CC(MIN)
C address is written to
CC
or V
CC
is greater than V
ACCESS*
CC
BAT
Power Control
. The FRAM must
FRAM
Operation
BAT
Yes
Yes
.
32kHz TCXO
No
No
BAT
is less than V
.
CC
is applied to
, the device
is applied,
ACCESS
RTC
Yes
Yes
Yes
Yes
CC
PF
CC
CC
. If
PF
,
correction to the oscillator. Once the oscillator is run-
ning, it continues to run as long as a valid power
source is available (V
tinues to measure the temperature and correct the
oscillator frequency every 64 seconds.
On the first application of power (V
I
date registers are reset to 01/01/00 01 00:00:00
(MM/DD/YY DOW HH:MM:SS).
The device provides for a pushbutton switch to be con-
nected to the RST output pin. When the device is not in
a reset cycle, it continuously monitors the RST signal
for a low going edge. If an edge transition is detected,
the device debounces the switch by pulling RST low.
After the internal timer has expired (PB
continues to monitor the RST line. If the line is still low,
the device continuously monitors the line looking for a
rising edge. Upon detecting release, the device forces
the RST pin low and holds it low for t
RST is also used to indicate a power-fail condition. When
V
generated, which forces the RST pin low. When V
returns to a level above V
t
tor is not running (see the Power Control section) when
V
goes high. The state of RST does not affect the operation
of the TCXO, I
With the clock source from the TCXO, the RTC provides
seconds, minutes, hours, day, date, month, and year
information. The date at the end of the month is automati-
cally adjusted for months with fewer than 31 days, includ-
ing corrections for leap year. The clock operates in either
the 24-hour or 12-hour format with an AM/PM indicator.
The clock provides two programmable time-of-day
alarms and a programmable square-wave output. The
INT/SQW pin either generates an interrupt due to alarm
condition or outputs a square-wave signal and the
selection is controlled by the bit INTCN.
The FRAM I
at a valid level. The RTC I
whenever either V
microcontroller connected to the device resets because
of a loss of V
microcontroller and the RTC I
become unsynchronized, e.g., the microcontroller resets
while reading data from the RTC. When the microcon-
2
REC
CC
CC
C address is written to the part (V
is applied, t
is lower than V
to allow the power supply to stabilize. If the oscilla-
2
C interface is accessible whenever V
2
CC
C interface, FRAM, or RTC functions.
REC
or other event, it is possible that the
CC
Pushbutton Reset Function
PF
is bypassed and RST immediately
CC
, an internal power-fail signal is
or V
or V
PF
BAT
, the RST pin is held low for
2
C interface is accessible
BAT
2
C communications could
is at a valid level. If a
), and the device con-
Real-Time Clock
CC
RST
BAT
) or when a valid
I
.
2
DB
), the time and
C Interface
), the device
CC
CC
is