71M6515H_11 Datasheet, PDF (41/60 Pages) Teridian Semiconductor Corporation – Up to 10ppmC precision ultra-stable voltage reference Digital temperature compensation

A Maxim Integrated Products Brand
71M6515H
Energy Meter IC
DATA SHEET
JULY 2011
STMASK (0x15)
The four bytes in this register enable interrupts when the corresponding bit in the STATUS register is set. The default value
for STMASK is zero.
When a bit in the STMASK register is set, an interrupt (IRQZ) is generated as soon as the corresponding bit in the STATUS
register is set. Interrupts indicated by IRQZ do not necessarily have to be synchronized with accumulation intervals. For
example, the toggling of a signal applied to the DIO pins (D0…D7), when the interrupt is enabled with the DIO_INT_CTRL
register, can cause an interrupt at any time.
Registers Controlling Temperature Measurement and Compensation
DEG_SCALE (0x1C)
This register holds the scale factor used to calculate the internal temperature value provided by the temperature sensor to
temperature in degrees Celsius (°C). The default value is 22721 and should not be changed.
FREQ_DELTA_T (0x11)
This register holds frequency and temperature information in two bytes each.
31
16 15
0
FREQUENCY (see Output Registers)
DELTA_T
Bits 15-0: These bits (DELTA_T) represent the temperature information relative to the value stored in the TEMP_NOM
register. One LSB is equivalent to 0.1°C. The formula used for DELTA_T is:
DELTA_T = -DEGSCALE*2^-22*(TEMP_RAW-TEMP_NOM)
TEMP_NOM (0x13)
This register holds the nominal (reference) temperature. During calibration, the host must write the value read from
TEMP_RAW to TEMP_NOM in order to enable temperature compensation. See the Meter Calibration section for details. The
temperature available in register DELTA_T is based on the difference between the current temperature, as provided in
TEMP_RAW, and the reference temperature provided by TEMP_NOM.
TEMP_RAW (0x12)
This read-only register holds the raw temperature provided by the temperature sensor on the 71M6515H chip. During
calibration, the host must write the value read from TEMP_RAW to TEMP_NOM in order to enable temperature
compensation.
Example: At calibration time, the raw temperature value of 853030 was read from the TEMP_RAW register and
written to the TEMP_NOM register. At a later time, the raw temperature register reads 844866. The 71M6515H
calculates the temperature difference to:
DELTA_T = -DEGSCALE*2^-22*(TEMP_RAW-TEMP_NOM) = 44
This value is interpreted as +4.4°C.
PPMC1_2 (0x1B)
This register holds the linear and squared compensation factors for the ADC temperature compensation. The allowed
range is (2¹⁵ – 1) to – (2¹⁵ – 1). Both words are reset to zero if TEMP_NOM equals zero.
31
16 15
0
PPMC = ADC linear factor (PPMC = 26.84 * PPM/°C )
PPMC2 = ADC quadratic factor (PPMC2 = 1374 * PPM/°C²)
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