Application Note
AN001016
TMD2755 Temperature
Sensor Function
Register Description and Usage
v1-00 • 2021-Feb-19
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Content Guide
Content Guide
1
2
2.1
3
3.1
Introduction ................................... 3
Register Descriptions ................... 4
Settings for the Temperature Sensor ........... 4
Recommended Sequences in SW
Driver .............................................. 6
Sequences from Prox to Temp Sensor ........ 6
3.2
4
5
Sequences from Temp Sensor to Prox ........ 6
Revision Information ..................... 8
Legal Information ........................... 9
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Introduction
1 Introduction
The purpose of this document is to describe TMD2755 registers that are related to the temperature sensor functionality and how to use them correctly. These registers are not published in the TMD2755 datasheet.
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2 Register Descriptions
2.1 Settings for the Temperature Sensor
2.1.1 CFG1 Register (0x91) Bit 7 enab_temp_sensor (Bit7)
Access RW
Description: Enable or disable the comparator for temp sensor
Default 0: Disable temp sensor comparator
Set to 1: Enable temp sensor comparator
2.1.2 ADCCFG Register (0xBF) Bit [1:0] adc_sel (Bit [1:0])
Access RW
Description: ADC input selection
Default 0: ADC input path for normal prox operation
Set to 1: ADC input path for temp sensor
2.1.3 ADCCFG Register (0xBF) Bit [3:2] adc_settling (Bit [3:2])
Access RW
Description: ADC settling time selection
Default 1: 2 µs for normal prox operation
Set to 3: 8 µs for temp sensor
TMD2755 Temperature Sensor Function
Register Descriptions
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2.1.4
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Register Descriptions
CALIB Register (0xD7) Bit 1 start_adc (Bit 1)
Access WS_SC (Write to start – self clearing)
Description: Manually start ADC conversion
Default 0: No manual ADC start
Set to 1: Manually start ADC conversion for temp sensor (ADC conversion is automatic for prox when
PEN is enabled)
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Recommended Sequences in SW Driver
3 Recommended Sequences in SW Driver
In some applications, there is a need to get the chip temperature information by reading out temp sensor ADCs periodically. At each time of setting up temp sensor and reading 10-bit temp ADCs from
PDATA registers, the ongoing prox operation is affected. The sequences in the SW driver have to be optimized to reduce turnaround time, and avoid unwanted prox related interrupts if it operates in interrupt mode.
3.1 Sequences from Prox to Temp Sensor
Figure 1 below shows a recommended sequence from normal prox operation to temp sensor
operation. The minimum lengths of the timers required are related to some of the prox configurations being used in an application.
Figure 1:
Sequences from Prox to Temp Sensor
Sequence Step
12
13
14
7
8
9
10
11
5
6
3
4
0
1
2
Actions/States
Ongoing prox operation
Disable PEN
Start timer1
Timer1 expires
Disable prox-related INTs
Clear prox-related flags
Disable PWEN
Disable hw prox_avg
Set enab_temp_sensor bit to 1
Set adc_sel to 1
Set adc_settling to 3 (8µs)
Set start_adc bit to 1
Start timer2
Timer2 expires
Read 10-bit temp ADC from Pdata registers
Notes
Enable Register (x80)
INTENAB Register (0xDD)
STATUS Register (0x94)
Enable Register (x80)
CALIBCFG Register (0xD9)
CFG1 Register (0x91) Bit 7
ADCCFG Register (0xBF) Bit [1:0]
ADCCFG Register (0xBF) Bit [3:2]
CALIB Register (0xD7) Bit 1
Pdata Registers 0x99 and 0x9A
3.2 Sequences from Temp Sensor to Prox
Figure 2 below shows a recommended sequence from temp sensor operation to prox operation. The
minimum lengths of the timer required are related to some of the prox configurations being used in an application.
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Figure 2:
Sequences from Temp Sensor to Prox
TMD2755 Temperature Sensor Function
Recommended Sequences in SW Driver
Sequence Step
6
7
4
5
2
3
0
1
8
9
10
11
Actions/States
Temp sensor option just finished
Set enab_temp_sensor bit to 0
Set adc_sel to 0
Set adc_settling to 1 (2µs)
Clear prox-related flags
Enable prox-related INTs
Set hw prox_avg to its original setting
Enable PWEN
Enable PEN
Start timer
Timer expires
First valid Pdata available. Prox now running
Notes
CFG1 Register (0x91) Bit 7
ADCCFG Register (0xBF) Bit [1:0]
ADCCFG Register (0xBF) Bit [3:2]
STATUS Register (0x94)
INTENAB Register (0xDD)
CALIBCFG Register (0xD9)
Enable Register (x80)
Enable Register (x80)
Pdata Registers 0x99 and 0x9A
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4 Revision Information
TMD2755 Temperature Sensor Function
Revision Information
Changes from previous version to current revision v1-00 Page
●
●
Initial version
Page and figure numbers for the previous version may differ from page and figure numbers in the current revision.
Correction of typographical errors is not explicitly mentioned.
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5 Legal Information
TMD2755 Temperature Sensor Function
Legal Information
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