FM3130 Datasheet, PDF (2/22 Pages) Ramtron International Corporation – Integrated RTC/Alarm and 64Kb FRAM

FM3130 Integrated RTC/Alarm with 64Kb FRAM
SCL
SDA
2-Wire
Interface
LockOut
VDD
VBAK
V_SW
-
+
FRAM
Array
Special
Function
Registers
RTC Cal.
Switched Power
RTC Registers
X1
RTC
X2
Alarm
Alarm
512Hz/SQW
ACS
Nonvolatile
Battery Backed
Figure 1. Block Diagram
Pin Descriptions
Pin Name
X1, X2
Type
I/O
ACS
Output
SDA
I/O
SCL
VBAK
VDD
VSS
Input
Supply
Supply
Supply
Pin Description
32.768 kHz crystal connection. When using an external oscillator, apply the clock to X1
and a DC mid-level to X2 (see Crystal Type section for suggestions).
Alarm/Calibration/SquareWave: This is an open-drain output that requires an external
pullup resistor. The alarm, calibration, and square wave functions all share this output.
In Alarm mode, this pin acts as the active-low alarm output. In Calibration mode, a 512
Hz square-wave is driven out. In SquareWave mode, the user may select a frequency of
1, 512, 4096, or 32768 Hz to be used as a continuous output. Refer to Table 3. Control
Bit Settings for ACS Pin to determine the bit settings for each mode.
Serial Data & Address: This is a bi-directional line for the two-wire interface. It is
open-drain and is intended to be wire-OR’d with other devices on the two-wire bus. The
input buffer incorporates a Schmitt trigger for noise immunity and the output driver
includes slope control for falling edges. A pull-up resistor is required.
Serial Clock: The serial clock line for the two-wire interface. Data is clocked out of the
part on the falling edge, and data into the device on the rising edge. The SCL input also
incorporates a Schmitt trigger input for noise immunity.
Backup supply voltage: A 3V battery or a large value capacitor. If no backup supply is
used, this pin should be tied to V_SS.
Supply Voltage.
Ground
Rev. 1.0
Sept. 2006
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