FDS_6533_6534_004
71M6533/71M6534 Data Sheet
3.16 MPU Firmware Library
All application-specific MPU functions mentioned in Section 3 Application Information are available from
Teridian as a standard ANSI C library and as ANSI C source code. The code is available as part of the
Demonstration Kit for the 71M6533/71M6534. The Demonstration Kits come with the 71M6533/71M6534
preprogrammed with demo firmware and mounted on a functional sample meter Demo Board. The Demo
Boards allow for quick and efficient evaluation of the IC without having to write firmware or having to
supply an in-circuit emulator (ICE).
3.17 Crystal Oscillator
The oscillator of the 71M6533/71M6534 drives a standard 32.768 kHz watch crystal. The oscillator has
been designed specifically to handle these crystals and is compatible with their high impedance and li-
mited power handling capability. The oscillator power dissipation is very low to maximize the lifetime of
any battery backup device attached to VBAT.
Board layouts with minimum capacitance from XIN to XOUT will require less battery current. Good
layouts will have XIN and XOUT shielded from each other.
Since the oscillator is self-biasing, an external resistor must not be connected across the crystal.
3.18 Meter Calibration
Once the Teridian 71M6533 and 71M6534 energy meter device has been installed in a meter system, it
must be calibrated. A complete calibration includes the following:
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•
Calibration of the metrology section, i.e. calibration for tolerances of the current sensors, voltage di-
viders and signal conditioning components as well as of the internal reference voltage (VREF).
Establishment of the reference temperature (Section 3.2) for temperature measurement and tempera-
ture compensation (Section 3.5).
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•
Calibration of the battery voltage measurement (Section 1.4.9).
Calibration of the oscillator frequency (Section 1.4.3) and temperature compensation for the RTC
(Section 3.5.4).
The metrology section can be calibrated using the gain and phase adjustment factors accessible to the
CE. The gain adjustment is used to compensate for tolerances of components used for signal condition-
ing, especially the resistive components. Phase adjustment is provided to compensate for phase shifts
introduced by the current sensors or by the effects of reactive power supplies.
Due to the flexibility of the MPU firmware, any calibration method, such as calibration based on energy, or
current and voltage can be implemented. It is also possible to implement segment-wise calibration (de-
pending on current range).
The 71M6533 and 71M6534 supports common industry standard calibration techniques, such as single-
point (energy-only), multi-point (energy, Vrms, Irms), and auto-calibration.
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