Datasheet

AT30TSE752A/754A/758A [DATASHEET]
Atmel-8854G-DTS-AT30TSE752A-754A-758A-Datasheet_102014
14
Figure 5-4. Interrupt Mode (Fault Tolerance Queue = 2) Delay Before Reading Register
5.3 Shutdown Mode
To reduce current consumption and save power, the device features a Shutdown mode that disables all internal device
circuitry except for the serial interface and POR circuits. While in the Shutdown mode, the internal temperature sensor is
not active, so no temperature measurements will be made. Entering and exiting the Shutdown mode is controlled by the
SD bit in the Configuration Register.
Entering the Shutdown mode can affect the ALERT pin depending on the Alarm Thermostat mode. If the device is
configured to operate in the Interrupt mode, then the ALERT pin will go inactive when the device enters the Shutdown
mode; however, the ALERT pin will not change states if the device is operating in the Comparator mode.
The fault count information will not change when the device enters or exits the Shutdown mode; therefore, the number of
previous temperature faults recorded by the internal fault counter will be retained unless the device is power-cycled or
reset. When exiting the Shutdown mode, the ALERT pin will go active if operating in Interrupt mode, a valid fault
condition exists, and the T
HIGH
and T
LOW
event cycles are maintained (i.e. T
HIGH
event before entering Shutdown mode
followed by a T
LOW
event when exiting Shutdown mode).
The device can be powered-down while in the Shutdown mode so that it will remain in the Shutdown mode after the
subsequent Power-up operation. This is accomplished by setting the NVSD bit in the Nonvolatile Configuration Register
to the Logic 1 state prior to power-down. Upon power-up or reset, the device will first copy the contents of the Nonvolatile
Data Registers into the Volatile Data Registers, after which the device will perform a single temperature measurement
and store the result in the Temperature Register. After this process is complete, the device will re-enter the Shutdown
mode.
5.3.1 One-Shot Mode
The AT30TSE752A/754A/758A features a One-Shot Temperature mode that allows the device to perform a single
temperature measurement while in the Shutdown mode. By keeping the device in the Shutdown mode and utilizing the
One-Shot mode, the AT30TSE752A/754A/758A can remain in a lower power state and only go active to take
temperature measurements on an as-needed basis. The internal fault counter will be updated when taking a temperature
measurement using the One-Shot mode; therefore, a valid fault condition can be generated by the One-Shot temperature
measurements. If operating in Comparator mode, then the fault condition will cause the ALERT pin to go either active or
inactive depending on if the fault condition is a result of a T
HIGH
or T
LOW
event. If operating in Interrupt mode, the fault
condition will cause the ALERT pin to pulse active for a short duration of time to indicate a T
HIGH
or T
LOW
event has
occurred. The ALERT pin will then return to the inactive state.
The One-Shot mode is controlled using the OS bit in the Configuration Register (see Section 6.3.1, “OS Bit” on page 20).
Temperature Measurements/Conversions
T
HIGH
Limit
Temperature
T
LOW
Limit
ALERT
(Active High, POL = 1)
ALERT
(Active Low, POL = 0)
Read Register Read Register