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SCM Functional Description
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Table 13-10. Band Gap Voltage and Temperature Sensor Signals Description
Pin
I/O
(1)
Description
SOC
I
Start Of Conversion signal. A transition to high starts a new ADC conversion cycle.
EOCZ
I
End of Conversion signal. When low, the signal indicates that the value of TEMP[6:0] is valid.
TEMP[7:0]
O
Temperature data from the temperature sensor. This value is valid when EOCZ is low.
CONTCONV
I
Configures the temperature sensor in continuous conversion mode.
0 – ADC single conversion mode
1– ADC continuous conversion mode
TSHUT
O
Thermal shutdown comparator output. The signal is low during normal operation and goes
high during a thermal shutdown event.
RESET
I
When low the temperature sensor is in RESET mode. This signal needs to be LOW when
OFFMODE is HIGH.
32K_FCLK
I
32-kHz functional clock from the CORE domain used by the temperature sensor during
temperature conversion.
(1)
I=Input, O=Output
All the configuration signals are available through the CONTROL.
register.
NOTE:
BGAPTS 32K_FCLK is used only for the temperature sensor. When ADC is not converting,
this clock can be switched off (32K_FCLK = 0). In this case, TEMP[7:0] retains the
temperature code obtained at the previous conversion.
13.4.6.1 Band Gap Voltage Reference
The band gap voltage reference feature provides several constant voltage and current references for its
internal circuits, but also for other analog modules.
The voltage reference signal is a 0.5-V output that is used internally by the module and is exported for
external modules or for tests.
The current reference signals consist in four lines that each supply a 1-µA current with a 1.8-V voltage.
These lines can be used to bias other modules.
13.4.6.2 Temperature Sensor
The temperature sensor feature is used to convert the temperature of the device into a decimal value
coded on 7 bits. An internal ADC (realized with a resistor array) is used for conversion. The recommended
operating temperatures must be from –40 to 125°C for standard conversion, and can go up to 160°C
when using the thermal shutdown comparator output (TSHUT signal). This signal indicates a too high
temperature of the device. This signal is internally connected to a general purpose input/output (GPIO)
pin. See
, General-Purpose Interface, for more information.
The temperature sensor offers two operating modes: a single conversion mode and a continuous
conversion mode.
13.4.6.2.1 Single Conversion Mode (CONTCONV = 0)
When the ADC is idle (EOCZ = 0), it is possible to ask for a single temperature conversion. To initiate a
new conversion, the start of conversion (SOC) signal must be asserted and maintained high until the end
of conversion (EOCZ) signal goes high, after which the SOC must be made low by writing 0 to the
CONTROL.
[9] SOC bit. Conversion completion is indicated by a negative
edge on EOCZ (CONTROL.
[8] EOCZ bit).
shows the timing sequence for a single temperature conversion.
2472
System Control Module
SWPU177N – December 2009 – Revised November 2010
Copyright © 2009–2010, Texas Instruments Incorporated
