lm75adp NXP Semiconductors, lm75adp Datasheet - Page 10

• Manufacturer Part Number: lm75adp
• Description: Digital Temperature Sensor And Thermal Watchdog
• Manufacturer: NXP Semiconductors

NXP Semiconductors
LM75A_4
Product data sheet
7.7 OS fault queue
7.8 Shutdown mode
7.9 Power-up default and power-on reset
The main difference between the two modes is that in OS comparator mode, the OS
output becomes active when Temp has exceeded T
below T
the state of the OS output; while in OS interrupt mode, once it has been activated either
by exceeding T
reading a register, then the OS output is reset.
Temperature limits T
output state will be undefined.
Fault queue is defined as the number of faults that must occur consecutively to activate
the OS output. It is provided to avoid false tripping due to noise. Because faults are
determined at the end of data conversions, fault queue is also defined as the number of
consecutive conversions returning a temperature trip. The value of fault queue is
selectable by programming the two bits B4 and B3 (OS_F_QUE[1:0]) in register Conf.
Notice that the programmed data and the fault queue value are not the same.
shows the one-to-one relationship between them. At power-up, fault queue data = 0 and
fault queue value = 1.
Table 14.
The device operation mode is selected by programming bit B0 (SHUTDOWN) of register
Conf. Setting bit SHUTDOWN to logic 1 will put the device into shutdown mode. Resetting
bit SHUTDOWN to logic 0 will return the device to normal mode.
In shutdown mode, the device draws a small current of approximately 3.5 A and the
power dissipation is minimized; the temperature conversion stops, but the I
interface remains active and register write/read operation can be performed. The OS
output remains unchanged.
The LM75A always powers-up in its default state with:
Fault queue data
OS_F_QUE[1]
0
0
1
1
•
•
•
•
•
•
Normal operation mode
OS comparator mode
T
T
OS output active state is LOW
Pointer value is logic 0
os
hyst
hyst
= 80 C
= 75 C
Fault queue table
, reading a register or putting the device into shutdown mode does not change
os
or dropping below T
os
and T
Rev. 04 — 10 July 2007
hyst
OS_F_QUE[0]
0
1
0
1
must be selected so that T
Digital temperature sensor and thermal watchdog
hyst
, the OS output will remain active indefinitely until
os
and reset when Temp has dropped
os
Fault queue value
Decimal
1
2
4
6
> T
hyst
. Otherwise, the OS
© NXP B.V. 2007. All rights reserved.
LM75A
2
C-bus
Table 14
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