71m6543h-igtr/f Maxim Integrated Products, Inc., 71m6543h-igtr/f Datasheet - Page 56

• Manufacturer Part Number: 71m6543h-igtr/f
• Description: Energy Meter Ic
• Manufacturer: Maxim Integrated Products, Inc.

71M6543F/H Data Sheet
2.5.6 71M6xx3 Temperature Sensor
The 71M6xx3 includes an on-chip temperature sensor for determining the temperature of its bandgap
reference. The primary use of the temperature data is to determine the magnitude of compensation
required to offset the thermal drift in the system for the compensation of the current measurement
performed by the71M6xx3. See the 71M6xxx Data Sheet for the equation to calculate temperature from the
71M6xx3 STEMP[10:0] reading. Also, see
See
STEMP[10:0] information from the 71M6xx3.
2.5.7 71M6543F/H Battery Monitor
The 71M6543F/H temperature measurement circuit can also monitor the batteries at the VBAT and
VBAT_RTC pins. The battery to be tested (i.e., VBAT or VBAT_RTC pin) is selected by TEMP_BSEL (I/O
RAM 0x28A0[7]).
When TEMP_BAT (I/O RAM 0x28A0[4]) is set, a battery measurement is performed as part of each
temperature measurement. The value of the battery reading is stored in register BSENSE[7:0] (I/O RAM
0x2885). The following equations are used to calculate the voltage measured on the VBAT pin (or
VBAT_RTC pin) from the BSENSE[7:0] and STEMP[10:0] values. The result of the equation below is in volts.
A slightly different equation is used for MSN mode and BRN mode, as follows.
In MSN mode, TEMP_PWR = 1 use:
56
TEMP_START
TEMP_PWR
TEMP_BSEL
TEMP_TEST[1:0] 2500[1:0]
STEMP[10:3]
STEMP[2:0]
BSENSE[7:0]
BCURR
Name
2.2.8.3 Control of the 71M6xx3 Isolated Sensor
VBAT
Location
2881[7:0]
2882[7:5]
2885[7:0]
28B4[6]
28A0[6]
28A0[7]
2704[3]
(
orVBAT
© 2008–2011 Teridian Semiconductor Corporation
_
RTC
Rst
0
0
0
0
–
0
)
=
3
Wk
3 .
–
–
–
–
–
0
4.5 Metrology Temperature Compensation
V
+
R/W
R/W
R/W
R/W
R/W
(
Dir
BSENSE
R
R
R
TEMP_PER[2:0] must be zero in order for TEMP_START
to function. If TEMP_PER[2:0] = 0, then setting
TEMP_START starts a temperature measurement.
Ignored in SLP and LCD modes. Hardware clears
TEMP_START when the temperature measurement is
complete.
Selects the power source for the temperature sensor:
1 = V3P3D, 0 = VBAT_RTC. This bit is ignored in
SLP and LCD modes, where the temperature sensor is
always powered by VBAT_RTC.
Selects which battery is monitored by the
temperature sensor: 1 = VBAT, 0 = VBAT_RTC
Test bits for the temperature monitor VCO.
TEMP_TEST must be 00 in regular operation. Any
other value causes the VCO to run continuously with
the control voltage described below.
The result of the temperature measurement.
The STEMP[10:0] value may be obtained in C with a
single 16-bit read and divide by 32 operation as
follows:
volatile int16_t xdata STEMP _at_0x2881;
fa = (float)(STEMP/32);
The result of the battery measurement.
Connects a 100 µA load to the battery selected by
TEMP_BSEL.
Description
TEMP_TEST
on page
−
142
1X
00
01
)
⋅
22
. 0
0246
for information on how to read the
V
Function
Normal operation
Reserved for factory test
Reserved for factory test
+
STEMP
⋅
. 0
000297
on page 88.
V
v1.0