MCP79402-I/MS Microchip Technology, MCP79402-I/MS Datasheet - Page 16

• Manufacturer Part Number: MCP79402-I/MS
• Description: Real Time Clock I2C GP RTCC 64B SRAM EUI-64
• Manufacturer: Microchip Technology
• Series: -r
• Type: Clock/Calendarr

Specifications of MCP79402-I/MS

• Features: Alarm, Leap Year, NVSRAM, Square Wave Output, Unique ID
• Memory Size: 64B
• Time Format: HH:MM:SS (12/24 hr)
• Date Format: YY-MM-DD-dd
• Interface: I²C
• Voltage - Supply: 1.8 V ~ 5.5 V
• Voltage - Supply, Battery: 1.3 V ~ 5.5 V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 8-TSSOP, 8-MSOP (0.118", 3.00mm Width)
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

MCP7940X
4.2.5
The MCP7940X has been designed to operate with a
standard 32.768 kHz tuning fork crystal. The on-board
oscillator has been characterized to operate with a
crystal of maximum ESR of 70K Ohms.
Crystals with a comparable specification are also suit-
able for use with the MCP7940X.
The table below is given as design guidance and a
starting point for crystal and capacitor selection.
EQUATION 4-1:
DS25009B-page 16
Micro Crystal
Citizen
Please work with your crystal vendor.
Manufacturer
CRYSTAL SPECS
C
load
=
-----------------------------
CX2
CX2 CX1
CM7V-T1A
CM200S-32.768KDZB-UT
+

CX1
Part Number
+
C
stray
7pF
6pF
Capacitance
Crystal
The following must also be taken into consideration:
• Pin capacitance (to be included in Cx2 and Cx1)
• Stray Board Capacitance
The recommended board layout for the oscillator area
is shown in
crystal and the load capacitors. In this example, C2 is
CX1, C3 is CX2 and the crystal is designated as Y1.
FIGURE 4-3:
Gerber files are available from
rtcc.
It is required that the final application should be tested
with the chosen crystal and capacitor combinations
across all operating and environmental conditions.
Please also consult with the crystal specification to
observe correct handling and reflow conditions and for
information on ideal capacitor values.
For more information please see AN1365, “RTCC Best
Practices Application Note” (DS01365).
10pF
10pF
Figure
CX1 Value
4-3. This actual board shows the
BOARD LAYOUT
 2011 Microchip Technology Inc.
12pF
8 pF
www/microchip.com/
CX2 Value