71M6521DE/71M6521FE
Energy Meter IC
DATASHEET
JANUARY 2008
Digital Pins:
Name
Type
Circuit Description
COM3,
COM2,
COM1,
COM0
O
O
5
5
LCD common outputs: These 4 pins provide the select signals for the LCD display.
Dedicated LCD segment output pins.
SEG0…SEG18
Multi-use pins, configurable as either LCD SEG driver or DIO. (DIO4 = SCK, DIO5 =
SDA when configured as EEPROM interface, WPULSE = DIO6, VARPULSE = DIO7
when configured as pulse outputs). If unused, these pins must be configured as
outputs.
SEG24/DIO4…
SEG31/DIO11
I/O
3, 4, 5
SEG34/DIO14…
SEG37/DIO17
SEG39/DIO19…
SEG41/DIO21
Multi-use pins, configurable as either LCD SEG driver or DIO. If unused, these
pins must be configured as outputs.
Multi-use pins, configurable as LCD driver or DIO (QFN 68 package only). If un-
used, these pins must be configured as outputs.
I/O
I/O
3, 4, 5
3, 4, 5
E_RXTX/SEG38
E_RST/SEG32
I/O
O
1, 4, 5
4, 5
Multi-use pins, configurable as either emulator port pins (when ICE_E pulled high) or
LCD SEG drivers (when ICE_E tied to GND).
E_TCLK/SEG33
ICE enable. When zero, E_RST, E_TCLK, and E_RXTX become SEG32, SEG33,
and SEG38 respectively. For production units, this pin should be pulled to GND to
disable the emulator port. This pin should be brought out to the programming inter-
face in order to create a way for reprogramming parts that have the SECURE bit set.
Multi-use pin, configurable as either Clock PLL output or LCD segment driver. Can
be enabled and disabled by CKOUT_EN.
ICE_E
I
2
CKTEST/SEG19
TMUXOUT
O
O
4, 5
4
Digital output test multiplexer. Controlled by TMUX[4:0].
Multi-use pin, configurable as Optical Receive Input or general DIO. When con-
figured as OPT_RX, this pin receives a signal from an external photo-detector used
in an IR serial interface. If unused, this pin must be configured as an output or
terminated to V3P3D or GNDD.
Multi-use pin, configurable as Optical LED Transmit Output, WPULSE, RPULSE, or
general DIO. When configured as OPT_TX, this pin is capable of directly driving an
LED for transmitting data in an IR serial interface. If unused, this pin must be
configured as an output or terminated to V3P3D or GNDD.
OPT_RX/DIO1
OPT_TX/DIO2
I/O
I/O
3, 4, 7
3, 4
DIO3
I/O
I
3, 4
3
DIO pin (QFN 68 package only)
This input pin resets the chip into a known state. For normal operation, this pin is
connected to GNDD. To reset the chip, this pin should be pulled high. No external
reset circuitry is necessary.
RESET
RX
I
O
I
3
4
7
UART input. If unused, this pin must be terminated to V3P3D or GNDD.
UART output.
TX
TEST
Enables Production Test. Must be grounded in normal operation.
Push button input. A rising edge sets the IE_PB flag and causes the part to wake up
if it is in SLEEP or LCD mode. PB does not have an internal pull-up or pull-down. If
unused, this pin must be terminated to GNDD.
PB
I
I
3
3
X4MHZ
This pin must be connected to GNDD.
Pin types: P = Power, O = Output, I = Input, I/O = Input/Output
The circuit number denotes the equivalent circuit, as specified on the following page.
v1.0
© 2005-2008 TERIDIAN Semiconductor Corporation
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