71M6534H Demo Board User’s Manual
Page: 55 of 86
© 2005-2007 TERIDIAN Semiconductor Corporation
V2-0
2.4.3 OSCILLATOR
The oscillator of the 71M6534 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 71M6534 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
Figure 2-9: Oscillator Circuit
It is not necessary to place an external resistor across the crystal.
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 10k
Ω
must be provided for both the SCL and SDA signals.
Figure 2-10: EEPROM Circuit
71M653X
C
1
C
2
33pF
7pF
71M653X
crystal
C
1
C
2
33pF
7pF
DIO4
DIO5
71M653X
EEPROM
SCL
SDA
V3P3D
10k
Ω
10k
Ω
DIO4
DIO5
71M653X
EEPROM
SCL
SDA
V3P3D
10k
Ω
10k
Ω
Содержание 71M6534H
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