xref: /openbmc/linux/Documentation/hwmon/ds620.rst (revision f5c27da4)
1Kernel driver ds620
2===================
3
4Supported chips:
5
6  * Dallas Semiconductor DS620
7
8    Prefix: 'ds620'
9
10    Datasheet: Publicly available at the Dallas Semiconductor website
11
12	       http://www.dalsemi.com/
13
14Authors:
15	Roland Stigge <stigge@antcom.de>
16	based on ds1621.c by
17	Christian W. Zuckschwerdt <zany@triq.net>
18
19Description
20-----------
21
22The DS620 is a (one instance) digital thermometer and thermostat. It has both
23high and low temperature limits which can be user defined (i.e.  programmed
24into non-volatile on-chip registers). Temperature range is -55 degree Celsius
25to +125. Between 0 and 70 degree Celsius, accuracy is 0.5 Kelvin. The value
26returned via sysfs displays post decimal positions.
27
28The thermostat function works as follows: When configured via platform_data
29(struct ds620_platform_data) .pomode == 0 (default), the thermostat output pin
30PO is always low. If .pomode == 1, the thermostat is in PO_LOW mode. I.e., the
31output pin PO becomes active when the temperature falls below temp1_min and
32stays active until the temperature goes above temp1_max.
33
34Likewise, with .pomode == 2, the thermostat is in PO_HIGH mode. I.e., the PO
35output pin becomes active when the temperature goes above temp1_max and stays
36active until the temperature falls below temp1_min.
37
38The PO output pin of the DS620 operates active-low.
39