71m6521fe Maxim Integrated Products, Inc., 71m6521fe Datasheet - Page 62

• Manufacturer Part Number: 71m6521fe
• Description: Energy Meter Ic
• Manufacturer: Maxim Integrated Products, Inc.

The MPU Demo Code supplied with the TERIDIAN Demo Kits has a direct interface for these coefficients and it directly con-
trols the RTC_DEC_SEC or RTC_INC_SEC registers. The Demo Code uses the coefficients in the form:
Note that the coefficients are scaled by 10, 100, and 1000 to provide more resolution. For our example case, the coefficients
would then become (after rounding):
Alternatively, the mains frequency may be used to stabilize or check the function of the RTC. For this purpose, the CE provides
a count of the zero crossings detected for the selected line voltage in the MAIN_EDGE_X address. This count is equivalent to
twice the line frequency, and can be used to synchronize and/or correct the RTC.
All digital input pins of the 71M6521DE/FE are compatible with external 5V devices. I/O pins configured as inputs do not
require current-limiting resistors when they are connected to external 5V devices.
Page: 62 of 101
Y_CAL = 109, Y_CALC = 12, Y_CALC2 = 7
CORRECTION
(
ppm
32768.5
32768.4
32768.3
32768.2
32768.1
32767.9
32767.8
32767.7
32767.6
32767.5
32768
)
=
Y
-50
_
10
© 2005-2008 TERIDIAN Semiconductor Corporation
CAL
Figure 31: Crystal Compensation
+
Connecting 5V Devices
T
⋅
-25
Y
_
100
CALC
crystal
curve fit
inverse curve
+
T
0
2
⋅
71M6521DE/71M6521FE
Y
_
1000
CALC
25
2
Energy Meter IC
50
DATASHEET
JANUARY 2008
v1.0