71M6531D Datasheet, PDF (69/115 Pages) Teridian Semiconductor Corporation – Energy Meter IC

FDS 6531/6532 005
Data Sheet 71M6531D/F-71M6532D/F
3.15 MPU Firmware Library
All application-specific MPU functions mentioned in the Application Information section 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 71M6531D/F and 71M6532D/F. The Demonstration Kits come with the
71M6531D/F or 71M6532D/F 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).
3.16 Crystal Oscillator
The oscillator 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 limited power handling capabili-
ty. The oscillator power dissipation is very low to maximize the lifetime of any battery backup device at-
tached 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.
3.17 Meter Calibration
Once the Teridian 71M6531D/F or 71M6532D/F energy meter device has been installed in a meter sys-
tem, it must be calibrated. A complete calibration includes the following:
• 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 3.3) for temperature measurement and tempera-
ture compensation (Section 3.4).
• Calibration of the battery voltage measurement (Section 1.5.13).
• Calibration of the oscillator frequency (Section 1.5.3) and temperature compensation for the RTC
(Section 3.4.4).
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 71M6531D/F and 71M6532D/F support common industry standard calibration techniques, such as single-
point (energy-only), multi-point (energy, Vrms, Irms) and auto-calibration.
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