Lines Matching +full:temperature +full:- +full:offset +full:- +full:millicelsius
1 # SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
3 ---
4 $id: http://devicetree.org/schemas/iio/afe/temperature-transducer.yaml#
5 $schema: http://devicetree.org/meta-schemas/core.yaml#
7 title: Temperature Transducer
10 - Liam Beguin <liambeguin@gmail.com>
13 A temperature transducer is a device that converts a thermal quantity
14 into any other physical quantity. This binding applies to temperature to
15 voltage (like the LTC2997), and temperature to current (like the AD590)
19 When an io-channel measures the output voltage of a temperature analog front
20 end such as a temperature transducer, the interesting measurement is almost
21 always the corresponding temperature, not the voltage output. This binding
26 T = (Isense(T) / alpha) + offset
27 T = 1 / (Rsense * alpha) * (V + offset * Rsense * alpha)
29 When using a temperature to voltage transducer, Rsense is set to 1.
31 The following circuits show a temperature to current and a temperature to
35 -----
37 +---+---+
39 +---+---+ -----
41 V proportional to T +----+----+
42 | D+ --+ |
43 +---- Vout | LTC2997 +--- Vout
44 | D- --+ |
45 +---+----+ +---------+
47 +---+----+ -----
49 -----
54 const: temperature-transducer
56 io-channels:
59 Channel node of a voltage io-channel.
61 '#io-channel-cells':
64 sense-offset-millicelsius:
66 Temperature offset.
67 This offset is commonly used to convert from Kelvins to degrees Celsius.
68 In that case, sense-offset-millicelsius would be set to <(-273150)>.
71 sense-resistor-ohms:
74 By default sense-resistor-ohms cancels out the resistor making the
75 circuit behave like a temperature transducer.
78 alpha-ppm-per-celsius:
80 Sometimes referred to as output gain, slope, or temperature coefficient.
82 alpha is expressed in parts per million which can be micro-amps per
83 degrees Celsius or micro-volts per degrees Celsius. The is the main
84 characteristic of a temperature transducer and should be stated in the
90 - compatible
91 - io-channels
92 - alpha-ppm-per-celsius
95 - |
96 ad950: temperature-sensor-0 {
97 compatible = "temperature-transducer";
98 #io-channel-cells = <0>;
99 io-channels = <&temp_adc 3>;
101 sense-offset-millicelsius = <(-273150)>; /* Kelvin to degrees Celsius */
102 sense-resistor-ohms = <8060>;
103 alpha-ppm-per-celsius = <1>; /* 1 uA/K */
105 - |
106 znq_tmp: temperature-sensor-1 {
107 compatible = "temperature-transducer";
108 #io-channel-cells = <0>;
109 io-channels = <&temp_adc 2>;
111 sense-offset-millicelsius = <(-273150)>; /* Kelvin to degrees Celsius */
112 alpha-ppm-per-celsius = <4000>; /* 4 mV/K */