71M6541D Datasheet, PDF (104/166 Pages) Maxim Integrated Products – 0.1% Accuracy Over 2000:1 Current Range Energy Meter ICs

71M6541D/F/G and 71M6542F/G Data Sheet
4.14 Flash Programming
4.14.1 Flash Programming via the ICE Port
Operational or test code can be programmed into the flash memory using either an in-circuit emulator or
the Flash Programmer Module (TFP-2) available from Teridian. The flash programming procedure uses
the E_RST, E_RXTX, and E_TCLK pins.
4.14.2 Flash Programming via the SPI Port
It is possible to erase, read and program the flash memory of the via the SPI port. See 2.5.10 SPI Slave
Port for a detailed description.
4.15 MPU Firmware Library
All application-specific MPU functions mentioned in 4 Application Information are featured in the
demonstration C source code supplied by Teridian. The code is available as part of the Demonstration Kit
for the 71M6541D/F/G and 71M6542F/G. The Demonstration Kits come with the 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).
4.16 Crystal Oscillator
The oscillator of the 71M6541D/F/G and 71M6542F/G 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 capability. The oscillator power dissipation is very low to
maximize the lifetime of any battery backup device attached to the VBAT_RTC pin.
Board layouts with minimum capacitance from XIN to XOUT require less battery current. Good layouts
have XIN and XOUT shielded from each other and from LCD and digital signals.
Since the oscillator is self-biasing, an external resistor must not be connected across the crystal.
4.17 Meter Calibration
Once the Teridian 71M654x energy meter device has been installed in a meter system, it must be
calibrated. A complete calibration includes the following:
• Establishment of the reference temperature (e.g., typically 22 ⁰C)
• Calibration of the metrology section, i.e., calibration for tolerances of the current sensors, voltage
dividers and signal conditioning components as well as of the internal reference voltage (VREF) at
the reference temperature (e.g., typically 22 ⁰C).
• Calibration of the oscillator frequency using the RTCA_ADJ[7:0] I/O RAM register (I/O RAM 0x2504).
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 conditioning,
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
(depending on current range).
The 71M6541D/F/G and 71M6542F/G support common industry standard calibration techniques, such
as single-point (energy-only), multi-point (energy, Vrms, Irms), and auto-calibration.
Teridian provides a calibration spreadsheet file to facilitate the calibration process. Contact your Teridian
representative to obtain a copy of the latest calibration spreadsheet file for the 71M654x.