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ADT75ARMZ

P1-P3P4-P6P7-P9P10-P12P13-P15P16-P18P19-P21P22-P24P25-P25
ADT75 Data Sheet
Rev. B | Page 12 of 24
ONE-SHOT MODE
Setting Bit D5 of the configuration register enables the one-shot
mode. When this mode is enabled, the ADT75 goes immediately
into shutdown mode and the current consumption is reduced to
typically 3 µA when V
DD
is 3.3 V and 5.5 µA when V
DD
is 5 V. A
one-shot temperature measurement is initiated when Address 0x04
is written to the address pointer register, which is writing to the
one-shot register. The ADT75 powers up, does a temperature
conversion, and powers down again.
Wait for a minimum of 60 ms after writing to the one-shot register
before reading back the temperature. This time ensures the ADT75
has time to power up and do a conversion. Reading back from the
one-shot register, Address 0x04, gives the resultant temperature
conversion. Reading from the temperature value register also
gives the same temperature value.
When either of the overtemperature detection modes is selected, a
write to the one-shot register, Address 0x04, causes the OS/ALERT
pin to go active if the temperature exceeds the overtemperature
limits. Refer to Figure 12 for more information on one-shot
OS/ALERT pin operation.
Note: In the interrupt mode, a read from any register resets the
OS/ALERT pin after it is activated by a write to the one-shot
register. In the comparator mode, once the temperature drops
below the value in the T
HYST
register, a write to the one-shot
register resets the OS/ALERT pin.
The one-shot mode is useful when one of the circuit design
priorities is to reduce power consumption.
TEMPERATURE
82°C
81°C
80°C
79°C
78°C
77°C
76°C
75°C
74°C
73°C
OS/ALERT PIN
(COMPARATOR MODE)
POLARITY = ACTIVE LOW
OS/ALERT PIN
(INTERRUPT MODE)
POLARITY = ACTIVE LOW
OS/ALERT PIN
(INTERRUPT MODE)
POLARITY = ACTIVE HIGH
OS/ALERT PIN
(COMPARATOR MODE)
POLARITY = ACTIVE HIGH
T
OS
T
HYST
TIME
READ
1
READ
1
READ
1
WRITE TO
0x04 REG.
2
WRITE TO
0x04 REG.
2
WRITE TO
0x04 REG.
2
05326-022
1
READ FROM ANY REGISTER.
2
THERE IS A 60ms DELAY BETWEEN WRITING TO THE
ONE-SHOT REGISTER AND THE OS/ALERT PIN GOING
ACTIVE. THIS IS DUE TO THE CONVERSION TIME.
Figure 12. One-Shot OS/ALERT Pin Operation
FAULT QUEUE
Bit D3 and Bit D4 of the configuration register are used to set
up a fault queue. Up to six faults are provided to prevent false
tripping of the OS/ALERT pin when the ADT75 is used in a
noisy temperature environment. The number of faults set in the
queue must occur consecutively to set the OS/ALERT output.
Data Sheet ADT75
Rev. B | Page 13 of 24
REGISTERS
The ADT75 contains six registers: four are data registers, one is
the address pointer register, and the final register is the one-shot
register. The configuration register is the only data register that
is 8 bits wide while the rest are 16 bits wide. The temperature
value register is the only data register that is read only. Both a read
and write can be performed on the rest of the data registers and
on the one-shot register. On power-up, the address pointer register
is loaded with 0x00 and points to the temperature value register.
Table 7. ADT75 Registers
Pointer Address Name Power-On Default
0x00
Temperature value
0x00
0x01 Configuration 0x00
0x02 T
HYST
setpoint 0x4B00 (75°C)
0x03 T
OS
setpoint 0x5000 (80°C)
0x04 One-shot 0xXX
Address Pointer Register
This 8-bit write only register stores an address that points to one
of the four data registers and selects the one-shot mode. P0 and
P1 select the data register to which subsequent data bytes are
written to or read from. P0, P1, and P2 are used to select the
one-shot mode by writing 04h to this register. A zero should be
written to the rest of the bits.
Table 8. Address Pointer Register
P7 P6 P5 P4 P3 P2 P1 P0
Default Settings at
Power-Up
0 0 0 0 0 0 0 0
Table 9. Register Addresses
P2
P1
P0
Register Selected
0 0 0 Temperature value
0 0 1 Configuration
0 1 0 T
HYST
setpoint
0 1 1 T
OS
setpoint
1 0 0 One-shot mode
ADT75 Data Sheet
Rev. B | Page 14 of 24
Temperature Value Register
This 16-bit read only register stores the temperature measured
by the internal temperature sensor. The temperature is stored in
twos complement format with the MSB being the temperature
sign bit. When reading from this register, the eight MSBs (Bit
D15 to Bit D8) are read first and then the eight LSBs (Bit D7 to
Bit D0) are read. The control register settings are the default
settings on power up.
Configuration Register
This 8-bit read/write register stores various configuration modes
for the ADT75. These modes are shutdown, overtemperature
interrupt, one-shot, SMBus alert function enable, OS/ALERT
pin polarity, and overtemperature fault queues. See Table 10.
MSB
LSB
D15 D14 D13 D12 D11 D10 D9 D8 D7 D6 D5 D4 D3 D2 D1 D0
0 0 0 0 0 0 0 0 0 0 0 0 N/A
1
N/A
1
N/A
1
N/A
1
1
N/A = not applicable.
Table 10.
Bit Configuration Mode Default Setting at Power-Up
D7 OS/SMBus alert 0
D6 Reserved 0
D5 One-shot 0
D4 Fault queue 0
D3 Fault queue 0
D2 OS/ALERT pin polarity 0
D1
Cmp/Int
0
D0 Shutdown 0
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ADT75ARMZ

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Buy ADT75ARMZ
Manufacturer:
Analog Devices Inc.
Description:
Board Mount Temperature Sensors 1 Deg C Accurate 12-Bit Digital
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