ds1338ua-33t-r Maxim Integrated Products, Inc., ds1338ua-33t-r Datasheet - Page 7

• Manufacturer Part Number: ds1338ua-33t-r
• Description: Ds1338, Ds1338c, Ds1338u, Ds1338z I?c Rtc With 56-byte Nv Ram
• Manufacturer: Maxim Integrated Products, Inc.

PIN DESCRIPTION
DETAILED DESCRIPTION
The DS1338 serial RTC is a low-power, full BCD clock/calendar plus 56 bytes of NV SRAM. Address and data are
transferred serially through an I
month, and year information. The end of the month date is automatically adjusted for months with fewer than 31
days, including corrections for leap year. The clock operates in either the 24-hour or 12-hour format with AM/PM
indicator. The DS1338 has a built-in power-sense circuit that detects power failures and automatically switches to
the V
—
8
1
2
3
4
5
6
7
8
BAT
PIN
supply.
4–13
16
14
15
16
—
—
1
2
3
SQW/OUT
NAME
GND
SDA
SCL
N.C.
V
V
X1
X2
BAT
CC
2
C interface. The clock/calendar provides seconds, minutes, hours, day, date,
32.768kHz Crystal Connections. The internal oscillator circuitry is designed for
operation with a crystal having a specified load capacitance (C
external 32.768kHz oscillator can also drive the DS1338. In this configuration,
the X1 pin is connected to the external oscillator signal and the X2 pin is
floated.
Note: For more information about crystal selection and crystal layout considerations,
refer to Application Note 58: Crystal Considerations with Dallas Real-Time Clocks.
Backup Supply Input for Lithium Cell or Other Energy Source. Battery voltage
must be held between the minimum and maximum limits for proper operation.
Diodes placed in series between the backup source and the V
prevent proper operation. If a backup supply is not required, V
grounded. UL recognized to ensure against reverse charging when used with a
lithium cell. For more information, visit www.maxim-ic.com/qa/info/ul.
Ground. DC power is provided to the device on these pins. V
power input. When voltage is applied within normal limits, the device is fully
accessible and data can be written and read. When a backup supply is
connected to the device and V
However, the timekeeping function continues unaffected by the lower input
voltage.
Serial Data. Input/output pin for the I
requires an external pullup resistor.
Serial Clock. Used to synchronize data movement on the serial interface
Square-Wave/Output Driver. When enabled and the SQWE bit set to 1, the
SQW/OUT pin outputs one of four square-wave frequencies (1Hz, 4kHz, 8kHz,
32kHz). It is open drain and requires an external pullup resistor. Operates with
either V
Primary Power Supply. When voltage is applied within normal limits, the device
is fully accessible and data can be written and read. When a backup supply is
connected to the device and V
The backup supply maintains the timekeeping function while V
No Connection. These pins are not connected internally, but must be grounded
for proper operation.
CC
or V
BAT
applied.
7 of 16
CC
CC
is below V
is below V
FUNCTION
2
C serial interface. It is open drain and
DS1338 I
PF
PF
, reads and writes are inhibited.
, reads and writes are inhibited.
2
C RTC with 56-Byte NV RAM
CC
BAT
BAT
CC
L
) of 12.5pF. An
is the primary
is absent.
pin may
must be