DS1841 Maxim Integrated Products, DS1841 Datasheet - Page 8

• Manufacturer Part Number: DS1841
• Description: Temperature-Controlled
• Manufacturer: Maxim Integrated Products

Temperature-Controlled, NV, I
Logarithmic Resistor
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The DS1841 features an internal 8-bit temperature sen-
sor that can drive the LUT and provide a measurement
of the ambient temperature over I
value stored in address 0Ch. The sensor is functional
over the entire operating temperature range and is
stored in signed two’s complement format with a resolu-
tion of 1°C/bit. See Table 2, Register 0Ch description for
the temperature sensor’s bit weights. To calculate the
temperature, treat the two’s complement binary value as
an unsigned binary number, then convert it to decimal.
If the result is greater than or equal to 128, subtract 256
from the result.
Table 3. LUT Registers and Temperature Ranges
8
_______________________________________________________________________________________
GND
SDA
SCL
V
LUT Mode and LUT Adder Mode Block Diagram (Update Mode Bit = 1)
CC
A0
A1
Temperature Conversion and Supply
TEMPERATURE (°C)
*NOTE THAT WHEN IN LUT OR LUT ADDER MODE, WR IS ACCESSED THROUGH 09h WHILE IVR REMAINS AT 00h.
INTERFACE
+101 or more
VOLTAGE
+99 to +100
SENSOR
+95 to +96
+97 to +98
TEMP
-40 or less
V
-39 to -38
-37 to -36
-35 to -34
I
2
CC
C
—
REGISTERS
CONTROL
LOGIC/
ADC
DATA
Temperature Conversion
Voltage Monitoring
V
TEMP
CC
0Ch
0Eh
CONTROL
2
(V)
C by reading the
TEMPERATURE VALUE FOR GIVEN
ADDRESS
REGISTER
(LUTAR)
LUT
08h
TEMPERATURE (HEX)
80h–C7h
72-BYTE
LOOKUP
DB to DC
DD to DE
D9 to DA
TABLE
5F to 60
61 to 62
63 to 64
(LUT)
D8
65
—
LUTVAL
INITIAL VALUE REGISTER (IVR)
The DS1841 monitors the internal temperature by
repeatedly polling the sensor’s result with update rate
t
nal temperature, and, based on that temperature,
points to the corresponding LUT address. Every two
degrees of temperature will convert into one tempera-
ture address slot. See Table 3 for a list of temperatures
and their corresponding LUT addresses.
The LUT features one-degree hysteresis to prevent
chattering if the measured temperature falls on the
boundary between two windows (see Figure 1).
FRAME
00h*
. During each cycle, the DS1841 reads the inter-
∑
LUTVAL + IVR
LUTVAL
2
OR
C,
REGISTER
WIPER
(WR)
09h*
CORRESPONDING LUT ADDRESS
POS 7Fh
POS 00h
(HEX)
C4
C5
C6
C7
80
81
82
83
—
R
S
RGND
RW
RH
LUT