![](http://datasheet.mmic.net.cn/310000/ADE7754_datasheet_16240613/ADE7754_15.png)
REV. PrG 01/03
PRELIMINARY TECHNICAL DATA
ADE7754
–
15
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PEAK DETECTION
The ADE7754 can also be programmed to detect when the
absolute value of the voltage or the current channel of one
phase exceeds a certain peak value. Figure 15 illustrates the
behavior of the PEAK detection for the voltage channel.
VPEAK[7:0]
VAP, VBP, or VCP
PKV Interrupt Flag
(Bit C of STATUS register)
PKV reset low
when RSTATUS register
is read
Read RSTATUS register
Figure 15 - ADE7754 Peak detection
Bits 2-3 of the Measurement Mode register define the phase
supporting the peak detection. Both current and voltage of
this phase can be monitored at the same time. Figure 15
shows a line voltage exceeding a threshold which is set in the
Voltage peak register (VPEAK[7:0]). The Voltage Peak
event is recorded by setting the PKV flag in the Interrupt
Status register. If the PKV enable bit is set to logic one in the
Interrupt Mask register, the
IRQ
logic output will go active
low - see
ADE7754 Interrupts
.
Peak Level Set
The contents of the VPEAK and IPEAK registers are respec-
tively compared to the absolute value of the most significant
byte output of the selected voltage and current channels.
Thus, for example, the nominal maximum code from the
current channel ADC with a full scale signal is 28F5C2h —
see
Current Channel Sampling
.
Therefore, writing 28h to the IPEAK register will put the
current channel peak detection level at full scale and set the
current peak detection to its least sensitive value.
Writing 00h will put the current channel detection level at
zero. The detection is done when the content of the IPEAK
register is smaller than the incoming current channel sample.
TEMPERATURE MEASUREMENT
The ADE7754 also includes an on-chip temperature sensor.
A temperature measurement is made every 4/CLKIN sec-
onds. The output from the temperature sensing circuit is
connected to an ADC for digitizing. The resultant code is
processed and placed in the Temperature register
(TEMP[7:0]). This register can be read by the user and has
an address of 08h -see
ADE7754 Serial Interface section
.
The contents of the Temperature register are signed (2's
complement) with a resolution of 4°C/LSB. The tempera-
ture register will produce a code of 00h when the ambient
temperature is approximately 129°C. The value of the
register will be : Temperature register = (Temperature (°C)
- 129)/4.
The temperature in the ADE7754 has an offset tolerance of
approximately ±5°C. The error can be easily calibrated out
by an MCU.