71m6515h Maxim Integrated Products, Inc., 71m6515h Datasheet - Page 43

• Manufacturer Part Number: 71m6515h
• Description: 71m6515h Energy Meter Ic
• Manufacturer: Maxim Integrated Products, Inc.

WH_A (0x00), WH_B (0x01), WH_C (0x02)
FREQ_DELTA_T (0x11)
MAIN_EDGE_CNT (0x35)
Registers Controlling Alarms and Thresholds
CREEP_THRSLD (0x1D)
SAG (0x2E)
Page: 43 of 57
These registers hold the real energy collected during the previous accumulation interval. The magnitude of the values is
determined by:
This register holds frequency and temperature information in two bytes each.
Bits 31-16: These bits (FREQUENCY) represent the frequency of the input signal selected with the F_SELECT bit of the
CONFIG register. One LSB is equivalent to 0.1Hz.
This register holds the number of zero crossings of the input phase selected by the F_SELECT bits in the CONFIG register
detected in the previous accumulation interval. The value in MAIN_EDGE_CNT can be used by the host to correct its own
RTC or to synchronize events to the line voltage.
The four bytes written to this register determine the creep threshold. Setting a creep threshold helps suppressing I2H, Wh
and VARh readings when the values of WSUM and VARSUM are determined to be below the creep threshold.
This register holds the voltage and timing threshold for sag detection.
Bits 15-0: These bits (SAG_CNT) hold the sag count. A sag condition must persist for at least SAG_CNT samples before a
sag alarm is generated. The allowed range is 1 to (2
SAG_CNT is:
Bits 31-16: These bits (SAGTHR) hold the voltage threshold that is to be applied for sag detection. The peak voltage must
exceed SAGTHR once each SAG_CNT samples in order to prevent a SAG warning. One LSB is defined as:
LSB
LSB
=
T = SAG_CNT*397μs
=
. 9
. 7
4045
The rounded down value of 8520 is written to the CREEP_THRSLD register.
8798
By multiplying with 3,600, we get 100Wh/h, which means the applied power is 100W.
Example: The register WH_A reads the value 236,675 for one accumulation interval of one second. Assuming
600V for VMAX, 208A for IMAX, and unity gain, we determine the real energy to be:
E = 236,675*600*208*9.4045*10
Example: The creep threshold of a meter operating with an accumulation interval of 1000ms is to be configured
of 8. The numerical value for the CREEP_THRSLD register is to be determined.
as 9.4045*10
to be 15mA at 240V. The meter is using a VMAX of 600V, an IMAX of 208A, and is not using the additional gain
With 15mA, the power per phase will be 3.6W, or 0.001Wh per second. With the LSB of WSUM readings given
⋅
10
⋅
2
n = 0.001Wh / (9.4045*10
−
16
13
⋅
VMAX
10
−
-13
9
In
VMAX
*VMAX*IMAX [Wh], we determine the value to:
_
IMAX
8
© 2005-2008 TERIDIAN Semiconductor Corporation
Wh
-13
-13
*VMAX*IMAX /In_8 Wh) = 8520.2
Wh = 0.0277781Wh.
15
-1), and the default is 80 (31.7ms). The time period defined by
Energy Meter IC
DATA SHEET
71M6515H
MARCH 2008
V1.4