http://www.www.datasheet4u.com

900,000+ Datasheet PDF Search and Download

Datasheet4U offers most rated semiconductors datasheets pdf




Xicor
Xicor


X1240V8I

Real Time Clock/Calendar with EEPROM


No Preview Available !

X1240V8I pdf
Preliminary Information
16K
X1240
2-Wire RTC
Real Time Clock/Calendar with EEPROM
FEATURES
• 2-Wire Interface interoperable with I2C.
—400kHz data transfer rate
• Secondary Power Supply Input with internal
switch-over circuitry.
• Year 2000 Compliant
• 2K bytes of EEPROM
—64 Byte Page Write Mode
—3 bit Block Lock
• Low Power CMOS
—<1µA Operating Current
—<3mA Active Current during Program
—<400µA Active Current during Data Read
• Single Byte Write Capability
• Typical Nonvolatile Write Cycle Time: 5ms
• High Reliability
—1,000,000 Endurance Cycles
—Guaranteed Data Retention: 100 Years
• Small Package Options
—8-Lead SOIC Package, 8L TSSOP Package
DESCRIPTION
The X1240 is a Real Time Clock with clock/calendar
circuits. The dual port clock register allows the clock to
operate, without loss of accuracy, even during read and
write operations.
The clock/calendar provides functionality that is con-
trollable and readable through a set of registers. The
clock, using a low cost 32.768kHz crystal input, accu-
rately tracks the time in seconds, minutes, hours, date,
day, month and years. It has leap year correction,
automatic adjustment for the year 2000 and months
with less than 31 days.
The device offers a backup power input pin. This
Vback pin allows the device to be backed up by a non-
rechargeable battery. The RTC is fully operational
from 1.8 to 5.5 volts.
The X1240 provides a 2K byte EEPROM array, giving
a safe, secure memory for critical user and configura-
tion data. This memory is unaffected by complete fail-
ure of the main and backup supplies.
BLOCK DIAGRAM
32.768kHz
X1
X2
Oscillator
Frequency 1Hz
Divider
Timer
Calendar
Logic
Time
Keeping
Registers
(SRAM)
SCL
SDA
Serial
Interface
Decoder
Control
Decode
Logic
8
Control
Registers
(EEPROM)
Status
Register
(SRAM)
16K
EEPROM
Array
©Xicor, Inc. 1994, 1995, 1996, 1997, 1998, 1999 Patents Pending
9900-3003.5 12/6/99 CM
1
Characteristics subject to change without notice



No Preview Available !

X1240V8I pdf
X1240
PIN CONFIGURATION
X1240
8 pin SOIC
X1 1
X2 2
NC 3
VSS 4
8
7
6
5
VCC
VBack
SCL
SDA
X1240
8 pin TSSOP
VBack
VCC
X1
1
2
3
8 SCL
7 SDA
6 VSS
X2 4 5 NC
PIN DESCRIPTIONS
Serial Clock (SCL)
The SCL input is used to clock all data into and out of
the device. The input buffer on this pin is always active
(not gated).
Serial Data (SDA)
SDA is a bidirectional pin used to transfer data into
and out of the device. It has an open drain output and
may be wire ORed with other open drain or open col-
lector outputs. The input buffer is always active (not
gated).
An open drain output requires the use of a pull-up
resistor. The output circuitry controls the fall time of
the output signal with the use of a slope controlled
pull-down. The circuit is designed for 400kHz 2-wire
interface speeds.
VBACK
This input provides a backup supply voltage to the
device. VBACK supplies power to the device in the
event the VCC supply fails.
X1, X2
The X1 and X2 pins are the input and output, respec-
tively, of an inverting amplifier that can be configured
for use as an on-chip oscillator. A 32.768kHz quartz
crystal is used. Recommeded crystals are Sieko VT-200
or Epson C-002RX. The crystal supplies a timebase
for a clock/oscillator. The internal clock can be driven
by an external signal on X1, with X2 left unconnected.
Figure 1. Recommended Crystal connection
18pF
43pF
10M
220K
X1
X2
POWER CONTROL OPERATION
The Power control circuit accepts a VCC and a VBACK
input. The power control circuit will switch to VBACK
when VCC < VBACK - 0.2V. It will switch back to VCC
when VCC exceeds VBACK.
Figure 2. Power Control
VBACK
VCC = VBACK -0.2V
VCC
Internal
Voltage
REAL TIME CLOCK OPERATION
The Real Time Clock (RTC) uses an external, 32.768KHz
quartz crystal to maintain an accurate internal repre-
sentation of the year, month, day, date, hour, minute,
and seconds. The RTC has leap-year correction and a
century byte. The clock will also correct for months hav-
ing fewer than 31 days and will have a bit that controls
24 hour or AM/PM format. When the X1240 powers up
after the loss of both VCC and VBACK, the clock will not
increment until at least one byte is written to the clock
register.
Reading the Real Time Clock
The RTC is read by initiating a Read command and
specifying the address corresponding to the register of
the Real Time Clock. The RTC Registers can then be
read in a Sequential Read Mode. Since the clock runs
continuously and a read takes a finite amount of time,
there is the possibility that the clock could change dur-
ing the course of a read operation. In this device, the
time is latched by the read command (falling edge of
2



Part Number X1240V8I
Description Real Time Clock/Calendar with EEPROM
Maker Xicor - Xicor
Total Page 19 Pages
PDF Download
X1240V8I pdf
Download PDF File
X1240V8I pdf
View for Mobile




Featured Datasheets

Part Number Description Manufacturers PDF
X1240V8 Real Time Clock/Calendar with EEPROM X1240V8
Xicor
PDF
X1240V8I Real Time Clock/Calendar with EEPROM X1240V8I
Xicor
PDF


Part Number Start With

0  1  2  3  4  5  6  7  8  9  A  B  C  D  E  F  G  H  I  J  K  L  M  N  O  P  Q  R  S  T  U  V  W  X  Y  Z

site map

webmaste! click here

contact us

Buy Components