cat34ts02 ON Semiconductor, cat34ts02 Datasheet - Page 16

• Manufacturer Part Number: cat34ts02
• Description: Digital Output Temperature Sensor With On-board Spd Eeprom
• Manufacturer: ON Semiconductor

CAT34TS02
REGISTER DATA FORMAT
The values used in the temperature value register and
the 3 temperature trip point registers are expressed in
two’s complement format. The measured temperature
value is expressed with 12-bit resolution, while the 3
trip temperature limits are set with 10-bit resolution. The
total temperature range is arbitrarily defined as 256°C,
thus yielding an LSB of 0.0625°C for the measured
temperature and 0.25°C for the 3 limit settings. Bit D12
in all temperature registers represents the sign, with a
‘0’ indicating a positive, and a ‘1’ a negative value. In
two’s complement format, negative values are obtained
by complementing their positive counterpart and adding
a ‘1’, so that the sum of opposite signed numbers, but
of equal absolute value, adds up to zero.
Note that trailing ‘0’ bits, are ‘0’ irrespective of polarity.
Therefore the don’t care bits (D1 and D0) in the 10-bit
resolution temperature limit registers, are always ‘0’.
Also note that temperatures below −20°C will produce
erroneous readings.
12-Bit Temperature Data Format
Doc. No. MD-1129 Rev. C
Binary (D12 to D0)
1 1110 1100 0000
1 1111 1111 1111
0 0000 0000 0000
0 0000 0000 0001
0 0001 1001 0000
0 0011 0010 0000
0 0111 1101 0000
1EC0
1FFF
Hex
7D0
000
001
190
320
Temperature
−0.0625°C
+0.0625°C
+125°C
−20°C
+25°C
+50°C
0°C
16
EVENT PIN FUNCTIONALITY
The EVENT
illustrated in Figure 14, and according to the operating
mode defined by the Configuration register.
In Interrupt Mode the EVENT
every time the temperature crosses one of the alarm
window limits, and can be de-asserted by writing a ‘1’
to the clear event bit in the configuration register.
When the temperature exceeds the critical limit, the
device switches to comparator mode and EVENT
remains asserted as long as the temperature stays
above the critical limit (setting the clear event bit will
have no effect in this case). When the temperature
drops below the critical limit, the device switches back
to
programmed in the configuration register.
In Comparator Mode, the EVENT
outside the alarm window limits, while in Critical
Temperature Mode, EVENT
the critical limit. The exact trip limits are determined by
the 3 temperature limit settings and the hystersis
offsets, as dictated by the corresponding Configu-
ration register bits (see also Figure 15).
The EVENT
shut-down command.
either
¯¯¯¯¯¯ output reacts to temperature changes as
¯¯¯¯¯¯ output will retain the state preceding a
interrupt
¯¯¯¯¯¯ is asserted only above
¯¯¯¯¯¯ output can be asserted
or
Characteristics subject to change without notice
¯¯¯¯¯¯ output is asserted
comparator
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mode,
¯¯¯¯¯¯
as