LM95234_07 NSC [National Semiconductor], LM95234_07 Datasheet - Page 11

• Manufacturer Part Number: LM95234_07
• Description: Quad Remote Diode and Local Temperature Sensor with SMBus Interface and TruTherm Technology
• Manufacturer: NSC [National Semiconductor]

1.2 POWER-ON-DEFAULT STATES
LM95234 always powers up to these known default states.
The LM95234 remains in these states until after the first con-
version.
1.
2.
3.
4.
5.
6.
7.
8.
TCRIT1 Masked,
TCRIT2
TCRIT3
Output
FIGURE 1. Conversion Rate Effect on Power Supply
Pin
All Temperature readings set to 0°C until the end of the
first conversion
Diode Model Select: Remote 1 set to 65 nm Intel
processor, Remote 2-4 set to MMBT3904
Remote offset for all channels 0°C
Configuration: Active converting, Fault Queue enabled
for Remote 3 and 4
Continuous conversion with all channels enabled,
time = 1s
Enhanced digital filter enabled for Remote 1 and 2
Status Registers depends on state of thermal diode
inputs
Local and Remote Temperature Limits for TCRIT1,
TCRIT2 and TCRIT3 outputs:
Remote
(°C)
85
85
85
4
Temperature Channel Limit
Masked,
Remote
(°C)
85
85
85
3
Current
Masked,
Remote
(°C)
110
85
85
2
Masked,
Remote
(°C)
110
85
85
1
20106306
Masked,
Masked,
Local
(°C)
85
85
85
11
9.
10. Revision ID set to 79h
1.3 SMBus INTERFACE
The LM95234 operates as a slave on the SMBus, so the
SMBCLK line is an input and the SMBDAT line is bidirectional.
The LM95234 never drives the SMBCLK line and it does not
support clock stretching. According to SMBus specifications,
the LM95234 has a 7-bit slave address. Three SMBus device
address can be selected by connecting A0 (pin 6) to either
Low, Mid-Supply or High voltages. The LM95234 has the fol-
lowing SMBus slave address:
1.4 TEMPERATURE CONVERSION SEQUENCE
Each of the 5 temperature channels of LM95234 can be
turned OFF independent from each other via the Channel
Enable Register. Turning off unused channels will increase
the conversion speed in the fastest conversion speed mode.
If the slower conversion speed settings are used, disabling
unused channels will reduce the average power consumption
of LM95234.
1.4.1 DIGITAL FILTER
In order to suppress erroneous remote temperature readings
due to noise as well as increase the resolution of the temper-
ature, the LM95234 incorporates a digital filter for Remote 1
and 2 Temperature Channels. When a filter is enabled the
filtered readings are used for the TCRIT comparisons. There
are two possible digital filter settings that are enabled through
the Filter Setting Register at register address 0Fh. The filter
for each channel can be set according to the following table:
Figure 2 describes the filter output in response to a step input
and an impulse input.
A0 Pin State
R1F[1:0] or R2F[1:0]
Mid-Supply
Manufacturers ID set to 01h
0
0
1
1
High
Low
0
1
0
1
SMBus Device Address A[6:0]
Hex
4Dh
4Eh
18h
Filter (equivalent to Level 2
Enhanced Filter (Filter with
filter of the LM86/LM89)
transient noise clipping)
Filter Setting
Reserved
No Filter
001 1000
100 1101
100 1110
Binary
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