71m6545h-igtr/f Maxim Integrated Products, Inc., 71m6545h-igtr/f Datasheet - Page 54

• Manufacturer Part Number: 71m6545h-igtr/f
• Description: Metrology Processors
• Manufacturer: Maxim Integrated Products, Inc.

Data Sheet 71M6545/H
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
54
TBYTE_BUSY
TEMP_PER[2:0]
TEMP_BAT
TEMP_START
TEMP_PWR
Reserved
TEMP_TEST[1:0] 2500[1:0]
STEMP[10:3]
STEMP[2:0]
BSENSE[7:0]
BCURR
Name
Table 43: I/O RAM Registers for Temperature and Battery Measurement
28A0[2:0]
Location
2881[7:0]
2882[7:5]
2885[7:0]
28A0[3]
28A0[4]
28B4[6]
28A0[6]
28A0[7]
2704[3]
© 2008–2011 Teridian Semiconductor Corporation
Rst
0
0
0
0
0
0
0
–
0
Wk
0
–
–
–
–
–
–
–
0
4.5 Metrology Temperature Compensation
R/W
R/W
R/W
R/W
R/W Must always be zero.
R/W
R/W
Dir
R
R
R
R
Indicates that hardware is still writing the 0x28A0
byte. Additional writes to this byte are locked out
while it is one. Write duration could be as long as 6 ms.
Sets the period between temperature measurements.
Automatic measurements can be enabled in any
mode (MSN and during ac power outages if the
VBAT_RTC voltage is within specification, as
supplied by a battery).
Causes the VBAT_RTC pin to be measured
whenever a temperature measurement is performed.
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.
This bit is ignored in SLP mode. 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 mode, where the temperature sensor is always
powered by 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 (VBAT_RTC
pin).
Description
TEMP_PER
TEMP_TEST
1-6
1X
0
7
00
01
Time
Manual updates (see TEMP_START)
2 ^ (3+TEMP_PER) (seconds)
Continuous
Function
Normal operation
Reserved for factory test
Reserved for factory test
on page 74.
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