MAX7501 Maxim, MAX7501 Datasheet - Page 8

• Manufacturer Part Number: MAX7501
• Description: Digital Temperature Sensors and Thermal Watchdog with Bus Lockup Protection
• Manufacturer: Maxim

The MAX7500/MAX7501/MAX7502 have an internal pn-
junction-based temperature sensor whose analog out-
put is converted to digital form using a 9-bit
sigma-delta ADC. The measured temperature and tem-
perature configurations are controlled by the tempera-
ture, configuration, T
Table
Read the measured temperature through the tempera-
ture register. The temperature data format is 9 bits,
two’s complement, and the register is read out in 2
bytes: an upper byte and a lower byte. Bit D15 is the
sign bit. When bit D15 is 1, the temperature reading is
negative. When bit D15 is zero, the temperature read-
ing is positive. Bits D14–D7 contain the temperature
data, with the LSB representing 0.5 C and the MSB
representing 64 C (see
Digital Temperature Sensors and Thermal
Watchdog with Bus Lockup Protection
Table
Table
X = Don’t care.
Table
8
Temperature
Configuration
T
T
TEMPERATURE (°C)
REGISTER NAME
1= Negative
HYST
OS
0 = Positive
_______________________________________________________________________________________
Sign bit
D15
2.
2. Register Functions
3. Temperature Register Definition
4. Temperature Data Output
+125
+0.5
+25
-0.5
-25
-55
0
64°C
MSB
D14
ADDRESS (hex)
HYST
0111 1101 0xxx xxxx
0001 1001 0xxx xxxx
0000 0000 1xxx xxxx
0000 0000 0xxx xxxx
1111 1111 1xxx xxxx
1110 0110 0xxx xxxx
1100 1000 0xxx xxxx
32°C
D13
Table
Register Descriptions
00
01
02
03
, and T
BINARY
UPPER BYTE
DIGITAL OUTPUT
3). The MSB is transmit-
16°C
D12
Temperature Register
OS
D11
8°C
registers. See
POR STATE (hex)
D10
4°C
4B0
500
7D0x
C90x
00
190x
008x
000x
FF8x
E70x
—
hex
2°C
D9
1°C
D8
ted first. The last 7 bits of the lower byte, bits D6–D0,
are don’t cares. When reading the temperature register,
bits D6–D0 must be ignored. When the measured tem-
perature is greater than +127.5 C, the value stored in
the temperature register is clipped to 7F8h. When the
measured temperature is below -64 C, the value in the
temperature register is clipped to BF8h.
During the time of reading the temperature register, any
changes in temperature are ignored until the read is
completed. The temperature register is updated upon
completion of the next conversion.
Table 3 lists the temperature register definition.
The 8-bit configuration register sets the fault queue, OS
polarity, shutdown control, and whether the OS output
functions in comparator or interrupt mode. When writing
to the configuration register, set bits D7, D6, and D5 to
zero. See
Bits D4 and D3, the fault queue bits, determine the
number of faults necessary to trigger an OS condition.
See
must occur to trip the OS output. The fault queue pre-
vents OS false tripping in noisy environments.
Set bit D2, the OS polarity bit, to zero to force the OS
output active low. Set bit D2 to 1 to set the OS output
polarity to active high. OS is an open-drain output
under all conditions and requires a pullup resistor to
output a high voltage. See
Set bit D1, the comparator/interrupt bit to zero to run
the over-temperature shutdown block in comparator
mode. In comparator mode, OS is asserted when the
POR STATE
0100 1011 0
0101 0000 0
0000 0000
(BINARY)
0.5°C
Table
LSB
D7
—
Table
6. The number of faults set in the queue
D6
x
5.
POR STATE (°C)
D5
x
D4
—
—
75
80
x
Figure
LOWER BYTE
Configuration Register
D3
x
4.
D2
x
Read only
WRITE
READ/
R/W
R/W
R/W
D1
x
D0
x