71M6521DE Datasheet, PDF (102/107 Pages) Teridian Semiconductor Corporation – Energy Meter IC

71M6521DE/DH/FE Data Sheet
PIN DESCRIPTIONS
Power/Ground Pins:
Name
GNDA
GNDD
V3P3A
V3P3SYS
V3P3D
VBAT
V2P5
Type
P
P
P
P
O
P
O
Circui
t
--
--
--
--
13
12
10
Description
Analog ground: This pin should be connected directly to the ground plane.
Digital ground: This pin should be connected directly to the ground plane.
Analog power supply: A 3.3V power supply should be connected to this pin, must be
the same voltage as V3P3SYS.
System 3.3V supply. This pin should be connected to a 3.3V power supply.
Auxiliary voltage output of the chip, controlled by the internal 3.3V selection switch.
In mission mode, this pin is internally connected to V3P3SYS. In BROWNOUT
mode, it is internally connected to VBAT. This pin is high impedance in LCD and
sleep mode.
Battery backup power supply. A battery or super-capacitor is to be connected
between VBAT and GNDD. If no battery is used, connect VBAT to V3P3SYS.
Output of the internal 2.5 V regulator. A 0.1µF capacitor to GNDA should be
connected to this pin.
Analog Pins:
Name
IA, IB
VA, VB
V1
VREF
XIN
XOUT
Type
I
I
I
O
I
Circui
t
6
6
7
9
8
Description
Line Current Sense Inputs: These pins are voltage inputs to the internal A/D
converter. Typically, they are connected to the outputs of current sensors. Unused
pins must be connected to V3P3A.
Line Voltage Sense Inputs: These pins are voltage inputs to the internal A/D
converter. Typically, they are connected to the outputs of resistor dividers. Unused
pins must be connected to V3P3A or tied to the voltage sense input that is in
use.
Comparator Input: This pin is a voltage input to the internal power-fail comparator.
The input voltage is compared to the internal BIAS voltage (1.6 V). If the input
voltage is above VBIAS, the comparator output will be high (1). If the comparator
output is lower, a voltage fault will occur and the chip will be forced to battery mode.
Voltage Reference for the ADC. This pin is normally disabled by setting the
VREF_CAL bit in the I/O RAM and can then be left unconnected. If enabled, a 0.1µF
capacitor to GNDA should be connected.
Crystal Inputs: A 32kHz crystal should be connected across these pins. Typically, a
27pF capacitor is also connected from each pin to GNDA. It is important to minimize
the capacitance between these pins. See the crystal manufacturer datasheet for
details.
Pin types: P = Power, O = Output, I = Input, I/O = Input/Output
The circuit number denotes the equivalent circuit, as specified under “I/O Equivalent Circuits”.
Page: 102 of 107
Rev 2