71M6521FE-IM Maxim Integrated Products, 71M6521FE-IM Datasheet - Page 15

• Manufacturer Part Number: 71M6521FE-IM
• Description: Current & Power Monitors & Regulators Residential Energy Meter IC
• Manufacturer: Maxim Integrated Products

Specifications of 71M6521FE-IM

• Lead Free Status / Rohs Status: Lead free / RoHS Compliant
• Other names: 783-71M6521FE-IM/F, 783-71M6521FE-IMR, 783-71M6521FE-IMR/F 783-71M6521FEIM-DB,

The end of each multiplexer cycle is signaled to the MPU by the CE_BUSY interrupt. At the end of each multiplexer cycle,
status information, such as sag data and the digitized input signal, is available to the MPU.
Figure 5 shows the accumulation interval resulting from PRE_SAMPS = 42 and SUM_CYCLES = 50, consisting of 2100 samples
of 397µs each, followed by the XFER_BUSY interrupt. The sampling in this example is applied to a 50Hz signal.
There is no correlation between the line signal frequency and the choice of PRE_SAMPS or SUM_CYCLES (even though when
SUM_CYCLES = 42 one set of SUM_CYCLES happens to sample a period of 16.6ms). Furthermore, sampling does not have to
start when the line voltage crosses the zero line, and the length of the accumulation interval need not be an integer multiple of
the signal cycles.
It is important to note that the length of the accumulation interval, as determined by N
PRE_SAMPS, is not an exact multiple of 1000ms. For example, if SUM_CYCLES = 60, and PRE_SAMPS = 00 (42), the
resulting accumulation interval is:
This means that accurate time measurements should be based on the RTC, not the accumulation interval.
v1.0
20ms
τ
=
© 2005-2008 TERIDIAN Semiconductor Corporation
N
Figure 4: Samples from Multiplexer Cycle
f
ACC
S
IA
Figure 5: Accumulation Interval
=
32768
VA
60
833ms
IB
13
⋅
42
Hz
VB
=
2520
2520
71M6521DE/71M6521FE
.
62
13/32768Hz = 397µs
per mux cycle
Hz
=
1/32768Hz =
30.518µs
999
.
75
Energy Meter IC
ACC
ms
, the product of SUM_CYCLES and
Interrupt to MPU
XFER_BUSY
DATASHEET
JANUARY 2008
Page: 15 of 101