71M6521DE TERIDIAN [Teridian Semiconductor Corporation], 71M6521DE Datasheet - Page 66

• Manufacturer Part Number: 71M6521DE
• Description: Energy Meter IC
• Manufacturer: TERIDIAN [Teridian Semiconductor Corporation]

µWire EEPROMs and other compatible devices should be connected to the DIO pins DIO4 and DIO5, as shown in Figure 34.
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
71M6521DE/FE. 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 71M6521DE/FE 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.
The RX pin should be pulled down by a 10kΩ resistor and additionally protected by a 100pF ceramic capacitor, as shown in
Figure 35.
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71M6521
71M6521
Connecting Three-Wire EEPROMs
© 2005-2008 TERIDIAN Semiconductor Corporation
Figure 34: Three-Wire EEPROM Connection
71M6521E
71M6521E
Figure 35: Connections for the RX Pin
DIO5
DIO5
DIOn
DIOn
DIO4
DIO4
TX
TX
RX
RX
UART0 (TX/RX)
10kΩ
10kΩ
100pF
100pF
71M6521DE/71M6521FE
10kΩ
10kΩ
10kΩ
10kΩ
V3P3D
V3P3D
EEPROM
EEPROM
DI
DI
DO
DO
SCLK
SCLK
CS
CS
TX
TX
RX
RX
Energy Meter IC
DATASHEET
JANUARY 2008
v1.0