xref: /linux/Documentation/hwmon/lm95234.rst (revision b8d312aa075f33282565467662c4628dae0a2aff)
1Kernel driver lm95234
2=====================
3
4Supported chips:
5
6  * National Semiconductor / Texas Instruments LM95233
7
8    Addresses scanned: I2C 0x18, 0x2a, 0x2b
9
10    Datasheet: Publicly available at the Texas Instruments website
11
12	       http://www.ti.com/product/lm95233
13
14  * National Semiconductor / Texas Instruments LM95234
15
16    Addresses scanned: I2C 0x18, 0x4d, 0x4e
17
18    Datasheet: Publicly available at the Texas Instruments website
19
20	       http://www.ti.com/product/lm95234
21
22Author: Guenter Roeck <linux@roeck-us.net>
23
24Description
25-----------
26
27LM95233 and LM95234 are 11-bit digital temperature sensors with a 2-wire
28System Management Bus (SMBus) interface and TrueTherm technology
29that can very accurately monitor the temperature of two (LM95233)
30or four (LM95234) remote diodes as well as its own temperature.
31The remote diodes can be external devices such as microprocessors,
32graphics processors or diode-connected 2N3904s. The chip's TruTherm
33beta compensation technology allows sensing of 90 nm or 65 nm process
34thermal diodes accurately.
35
36All temperature values are given in millidegrees Celsius. Temperature
37is provided within a range of -127 to +255 degrees (+127.875 degrees for
38the internal sensor). Resolution depends on temperature input and range.
39
40Each sensor has its own maximum limit, but the hysteresis is common to all
41channels. The hysteresis is configurable with the tem1_max_hyst attribute and
42affects the hysteresis on all channels. The first two external sensors also
43have a critical limit.
44
45The lm95234 driver can change its update interval to a fixed set of values.
46It will round up to the next selectable interval. See the datasheet for exact
47values. Reading sensor values more often will do no harm, but will return
48'old' values.
49