LM95235EVAL/NOPB National Semiconductor, LM95235EVAL/NOPB Datasheet - Page 12

• Manufacturer Part Number: LM95235EVAL/NOPB
• Description: BOARD EVALUATION LM95235
• Manufacturer: National Semiconductor
• Series: PowerWise®, TruTherm®r

Specifications of LM95235EVAL/NOPB

• Sensor Type: Temperature
• Sensing Range: -40°C ~ 125°C
• Interface: SMBus (2-Wire/I²C)
• Sensitivity: ±1°C
• Voltage - Supply: 3 V ~ 3.6 V
• Embedded: Yes, MCU, 8-Bit
• Utilized Ic / Part: LM95235
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Other names: LM95235EVAL

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Level Output Current with the supply voltage at 3.0V, is
82 kΩ (5%) or 88.7 kΩ (1%).
1.7 T_CRIT OUTPUT AND TCRIT LIMIT
The LM95235's T_CRIT pin is an active-low open-drain out-
put that is triggered when the local and/or the remote tem-
perature conversion is above the limits defined by the Remote
and/or Local Limit registers. The state of the T_CRIT pin will
return to the HIGH state when both the Local and Remote
temperatures are below the values programmed into the Limit
Registers less the value in the Common Hysteresis Register.
Additionally, if the remote temperature exceeds the value in
the Remote TCRIT Limit Register the Status Bit for Remote
TCRIT (RTCRIT), in Status Register 1, is set to 1. In the same
way if the local temperature exceeds the value in the Local
Shared OS and TCRIT Limit Register the Status Bit for the
Shared Local OS and TCRIT (LOC) bit in Status Register 1 is
set to 1.The T_CRIT output and the Status Register flags are
updated after every Local and Remote temperature conver-
sion. See Figure 4
1.8 OS OUTPUT AND OS LIMIT
The LM95235's OS/A0 pin is selected as an OS digital output
as described in Section 1.3. As an OS pin, it is activated
whenever the local and/or remote temperature conversion is
above the limits defined by the Limit registers. If the remote
temperature exceeds the value in the Remote OS Limit Reg-
ister the Status Bit for Remote OS (ROS) in Status Register
1 is set to 1. In the same way if the local temperature exceeds
the value in the Local Shared OS and TCRIT Limit Register
the Status Bit for the Shared Local OS and TCRIT (LOC) bit
in Status Register 1 is set to 1. The state of the T_CRIT pin
output will return to the HIGH state when both the Local and
Remote temperatures are below the values programmed into
the Limit Registers less the value in the Common Hysteresis
Register. The OS output and the Status Register flags are
updated after every Local and Remote temperature conver-
sion. See Figure 5.
FIGURE 4. T_CRIT Comparator Temperature Response
Diagram
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1.9 DIODE FAULT DETECTION
The LM95235 is equipped with operational circuitry designed
to detect fault conditions concerning the remote diodes. In the
event that the D+ pin is detected as shorted to GND, D−,
V
128.000 °C if signed format is selected and +255.875 °C if
unsigned format is selected. In addition, the Status Register
1 bit D2 is set.
1.10 COMMUNICATING with the LM95235
The data registers in the LM95235 are selected by the Com-
mand Register. At power-up the Command Register is set to
“00”, the location for the Read Local Temperature Register.
The Command Register latches the last location it was set to.
Each data register in the LM95235 falls into one of four types
of user accessibility:
1.
2.
3.
4.
A Write to the LM95235 will always include the address byte
and the command byte. A write to any register requires one
data byte.
Reading the LM95235 can take place either of two ways:
1.
2.
The data byte has the most significant bit first. At the end of
a read, the LM95235 can accept either acknowledge or No
Acknowledge from the Master (No Acknowledge is typically
used as a signal for the slave that the Master has read its last
byte). When retrieving all 11 bits from a previous remote diode
temperature measurement, the master must insure that all 11
bits are from the same temperature conversion. This may be
achieved by reading the MSB register first. The LSB will be
locked after the MSB is read. The LSB will be unlocked after
being read. If the user reads MSBs consecutively, each time
the MSB is read, the LSB associated with that temperature
will be locked in and override the previous LSB value locked-
in.
DD
or D+ is floating, the Remote Temperature reading is –
Read only
Write only
Write/Read same address
Write/Read different address
If the location latched in the Command Register is correct
(most of the time it is expected that the Command
Register will point to one of the Read Temperature
Registers because that will be the data most frequently
read from the LM95235), then the read can simply
consist of an address byte, followed by retrieving the data
byte.
If the Command Register needs to be set, then an
address byte, command byte, repeat start, and another
address byte will accomplish a read.
FIGURE 5. OS Temperature Response Diagram
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