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71M6513/71M6513H Demo Board User’s Manual
Page: 56 of 112
©
2005-2006 TERIDIAN Semiconductor Corporation
Revision 5.6
2.4.3 OSCILLATOR
The oscillator of the 71M6513 drives a standard 32.768kHz watch crystal (see Figure 2-9). Crystals of this type
are accurate and do not require a high current oscillator circuit. The oscillator in the 71M6513 has been
designed specifically to handle watch crystals and is compatible with their high impedance and limited power
handling capability. The oscillator power dissipation is very low to maximize the lifetime of any battery backup
device attached to the VBAT pin.
crystal
XOUT
XIN
71M651X
Figure 2-9: Oscillator Circuit
It is not necessary to place an external resistor across the crystal, i.e. R91 on the
D6513T3B2 Demo Board must not be populated.
Capacitor values for the crystal must be <15pF.
2.4.4 EEPROM
EEPROMs should be connected to the pins DIO4 and DIO5 (see Figure 2-10). These pins can be switched from
regular DIO to implement an I2C interface by setting the I/O RAM register DIO_EEX (0x2008[4]) to 1. Pull-up
resistors of 3k
Ω
must be provided for both the SCL and SDA signals.
DIO4
DIO5
651X
EEPROM
SCL
SDA
V3P3
3k
Ω
Figure 2-10: EEPROM Circuit
10pF
10pF
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