71M6521DH MAXIM [Maxim Integrated Products], 71M6521DH Datasheet - Page 63

• Manufacturer Part Number: 71M6521DH
• Description: Energy Meter ICs
• Manufacturer: MAXIM [Maxim Integrated Products]

71M6521DE/DH/FE Data Sheet
Temperature Compensation: The CE provides the bandgap temperature to the MPU, which then may digitally com-
pensate the power outputs for the temperature dependence of VREF, using the CE register GAIN_ADJ. Since the
band gap amplifier is chopper-stabilized via the CHOP_EN bits, the most significant long-term drift mechanism in the
voltage reference is removed.
The MPU, not the CE, is entirely in charge of providing temperature compensation. The MPU applies the following
formula to determine GAIN_ADJ (address 0x12). In this formula TEMP_X is the deviation from nominal or calibration
temperature expressed in multiples of 0.1°C:
In a production electricity meter, the 71M6521DE/DH/FE is not the only component contributing to temperature de-
pendency. A whole range of components (e.g. current transformers, resistor dividers, power sources, filter capacitors)
will contribute temperature effects.
Rev 2
Since the output of the on-chip temperature sensor is accessible to the MPU, temperature-compensation
mechanisms with great flexibility are possible. MPU access to GAIN_ADJ permits a system-wide temperature
correction over the entire meter rather than local to the chip.
GAIN
-1000
-1400
Figure 31: Error Band for VREF over Temperature (High-Accuracy Parts)
1400
1000
-200
-600
600
200
-40
_
ADJ
Error Band (PPM) over Temperature (°C)
=
-20
16385
+
TEMP
0
±20 PPM/°C
±20 PPM/°C
_
2
20
X
14
⋅
PPMC
40
+
TEMP
60
_
X
2
23
2
⋅
PPMC
80
2
Page: 63 of 107