71M6515H
Energy Meter IC
DATA SHEET
MARCH 2008
The SSI timing is shown in Figure 12.
If 16bit fields
If 32bit fields
If SSI_CKGATE =1
If SSI_CKGATE =1
SFR (Output)
SCLK (Output)
SSDATA (Output)
31 30
16 15
1
0
31 30
16 15
1
0
31
1
0
SSI_BEG
SSI_BEG+1
SSI_END
MUX_STATE
Figure 12: SSI Timing (SSI_FPOL = SSI_RDYPOL = 0)
Fault and Reset Behavior
Reset Mode
When RESETZ is pulled low or when VFLT < V3P3/2, all activity (i.e. sampling of analog signals, CE, generation of digital
outputs) in the chip stops while the analog circuits are active. The exceptions are the oscillator and RTC module, which
continue to run. Additionally, all I/O Register bits are cleared. As long as VFLT > V3P3/2, the internal 2.5V regulator will
continue to provide power to the digital section.
Once initiated, the reset mode will persist until the reset timer times out. This will occur in 4100 cycles of the real time clock
after RESETZ goes high, at which time the 71M6515H will begin executing its preboot and boot sequences.
Power Fault Circuit
The power fault comparator compares the voltage at the VFLT pin to V3P3/2. The comparator output internally enables the
battery backup protection for oscillator, RTC and RAM during the power fail mode.
Temperature Compensation
Voltage Reference
The internal voltage reference of the 71M6515H is calibrated at 25°C during device manufacture. The 71M6515H is given
additional temperature-related calibrations which further compensate its ADC gain and allow it to achieve 10PPM/°C over
±60°C temperature range.
Temperature Sensor
The device includes an on-chip temperature sensor for determining the temperature of the bandgap reference. The primary
use of the temperature data is to determine the magnitude of compensation required to offset thermal drift in the system. The
temperature sensor is read once per accumulation interval.
Temperature measurement can be implemented with the following steps:
1) At a known temperature TN, read the TEMP_RAW register and write the value into TEMP_NOM register.
2) Read the DELTA_T register at the known temperature. The obtained value should be <±0.1°C.
3) The temperature T (in °C) at any environment can be obtained by reading the DELTA_T register and applying the
following formula:
DELTA_T
T = TN +
10
Temperature Compensation for Energy Measurements
TEMP_NOM is one of the calibration parameters that must be loaded by the host in order to enable temperature measurement
and thereby temperature compensation.
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