71M6521BE
Energy Meter IC
DATA SHEET
JANUARY 2008
Connecting I2C EEPROMs
I2C EEPROMs or other I2C compatible devices should be connected to the DIO pins DIO4 and DIO5, as shown in Figure 31.
Pull-up resistors of roughly 10kΩ to V3P3D (to ensure operation in BROWNOUT mode) should be used for both SCL and SDA
signals. The DIO_EEX register in I/O RAM must be set to 01 in order to convert the DIO pins DIO4 and DIO5 to I2C pins SCL
and SDA.
V3P3D
6521B
10kΩ
EEPROM
DIO4
DIO5
SCL
SDA
Figure 31: I2C EEPROM Connection
Connecting Three-Wire EEPROMs
µWire EEPROMs and other compatible devices should be connected to the DIO pins DIO4 and DIO5, as shown in Figure 32.
DIO5 connects to both the DI and DO pins of the three-wire device. The CS pin must be connected to a vacant DIO pin of the
71M6521BE. A pull-up resistor of roughly 10kΩ to V3P3D (to ensure operation in BROWNOUT mode) should be used for the
DI/DO signals, and the CS pin should be pulled down with a resistor to prevent that the three-wire device is selected on power-
up, before the 71M6521BE can establish a stable signal for CS. The DIO_EEX register in I/O RAM must be set to 10 in order to
convert the DIO pins DIO4 and DIO5 to uWire pins. The pull-up resistor for DIO5 may not be necessary.
V3P3D
6521B
10kΩ
10kΩ
EEPROM
SCLK
DI
DIO4
DIO5
DIOn
DO
CS
10kΩ
Figure 32: Three-Wire EEPROM Connection
V1.0
© 2005-2008 TERIDIAN Semiconductor Corporation
Page: 63 of 97
TERIDIAN [ TERIDIAN SEMICONDUCTOR CORPORATION ]
