MAX1617 Datasheet, PDF (10/12 Pages) ON Semiconductor – SMBus Temperature Sensor with Internal and External Diode Input

MAX1617
Configuration Register (Config), 8–Bits,
Read/Write
Configuration Register (Config)
D[7]
D[6]
D[5] D[4] D[3] D[2] D[1] D[0]
Mask1 Chip Stop Reserved
Bit
D[7]
D[6]
D[5]—D[0]
POR State
0
0
0
Function
Interrupt Mask
(see text)
Standby switch
Reserved —
Always returns
zero when read.
Operation
1 = mask ALERT
0 = don’t mask
ALERT
1 = standby,
0 = normal
N/A
A/D Conversion Rate Register (CONV_RATE),
8–Bits, Read/Write
A/D Conversion Rate Register (CONV_RATE)
D[7] D[6] D[5] D[4] D[3] D[2] D[1] D[0]
Reserved
MSB X LSB
Bit
D[7:3]
D[2:0]
POR State
0
010b
Function
Reserved — Always
returns zero when
read.
Conversion rate bits.
Operation
N/A
See below.
A/D Conversion Rate Selection
D2
D1
D0 Conversion Rate Samples/sec
0
0
0 0.0625
0
0
1 0.125
0
1
0 0.25
0
1
1 0.5
1
0
0 1.0
1
0
1 2.0
1
1
0 4.0
1
1
1 8.0
NOTE: Conversion rate denotes actual sampling of both internal
and external sensors.
Temperature Registers, 8–Bits, Read–Only
(INT_TEMP, EXT_TEMP)
The binary value (2’s complement format) in these two
registers represents temperature of the internal and external
sensors following a conversion cycle. The registers are
automatically updated in an alternating manner.
Internal Temperature Register (INT_TEMP)
D[7] D[6] D[5] D[4] D[3] D[2] D[1] D[0]
MSB x
x
x
x
x
x LSB
External Temperature Register (EXT_TEMP)
D[7] D[6] D[5] D[4] D[3] D[2] D[1] D[0]
MSB x
x
x
x
x
x LSB
In the two temperature data and four threshold setpoint
registers, each unit value represents one degree (Celsius).
The value is in 2’s–complement binary format such that a
reading of 00000000b corresponds to 0°C. Examples of this
temperature–to–binary value relationship are shown in the
following table.
Temperature–to–Digital Value Conversion (INT_TEMP,
EXT_TEMP, INT_HLIM, INT_LLIM,EXT_HLIM,
EXT_LLIM)
Actual
Temperature
Rounded
Temperature
Binary
Value
Hex
Value
+130.00°C
+127°C
01111111
7F
+127.00°C
+127°C
01111111
7F
+126.50°C
+127°C
01111111
7F
+25.25°C
+25°C
00011001
19
+0.50°C
+1°C
00000001
01
+0.25°C
0°C
00000000
00
0.00°C
0°C
00000000
00
—0.25°C
0°C
00000000
00
—0.50°C
0°C
00000000
00
—0.75°C
—1°C
11111111
FF
—1.00°C
—1°C
11111111
FF
—25.00°C
—25°C
11100111
E7
—25.25°C
—25°C
11100110
E7
—54.75°C
—55°C
11001001
C9
—55.00°C
—55°C
11001001
C9
—65.00°C
—65°C
10111111
BF
Temperature Threshold Setpoint Registers,
8–Bits, Read–Write (INT_HLIM, INT_LLIM,
EXT_HLIM, EXT_LLIM)
These registers store the values of the upper and lower
temperature setpoints for event detection. The value is in
2’s–complement binary. INT_HLIM and INT_LLIM are
compared with the INT_TEMP value, and EXT_HLIM and
EXT_LLIM are compared with EXT_TEMP. These
registers may be written at any time.
Internal High Limit Setpoint Register (INT_HLIM)
D[7] D[6] D[5] D[4] D[3] D[2] D[1] D[0]
MSB x
x
x
x
x
x LSB
Internal Low Limit Setpoint Register (INT_LLIM)
D[7] D[6] D[5] D[4] D[3] D[2] D[1] D[0]
MSB x
x
x
x
x
x
LS
External High Limit Setpoint Register (EXT_HLIM)
D[7] D[6] D[5] D[4] D[3] D[2] D[1] D[0]
MSB x
x
x
x
x
x LSB
External Low Limit Setpoint Register (EXT_LLIM)
D[7] D[6] D[5] D[4] D[3] D[2] D[1] D[0]
MSB x
x
x
x
x
x LSB
NOTE: POR states:
INT_HLIM
INT_LLIM
EXT_HLIM
EXT_LLIM
01111111b
11001001b
01111111b
11001001b
+127°C
—55°C
+127°C
—55°C
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