sx8654 Semtech Corporation, sx8654 Datasheet - Page 39

• Manufacturer Part Number: sx8654
• Description: Haptics Enabled 4/5-wire Resistive Touchscreen Controller With Proximity Sensing
• Manufacturer: Semtech Corporation

ADVANCED COMMUNICATIONS & SENSING
7
The chip includes a temperature sensor which monitors the chip’s junction temperature. Its purpose is to provide
over-temperature information to the host and if needed automatically shutdown chip operation for thermal
protection.
If TEMPALWAYSON = 0 (default), the temperature sensor will perform measurements only if the chip is active
i.e.
(PROXSCANPERIOD != 0) or haptics interface enabled (HAPTTYPEEN != 00). The temperature sensor will
perform a measurement every ~32 ms (1024/FOSCL) but not during ADC conversions (temperature sensing
delayed accordingly).
If TEMPALWAYSON = 1, the temperature sensor will always perform a measurement every ~32 ms
independently from chip activity (i.e. also when the chip is inactive and during ADC conversions).
Each measurement is compared with two internally hard-coded thresholds:
Each of these thresholds is associated to a status flag (TEMPWARNINGSTAT, TEMPALARMSTAT) which
edges can be mapped to generate an interrupt to the host.
Additionally, during an alarm situation (i.e. temperature > alarm level) all chip operations (i.e. touchscreen,
proximity, haptics) are automatically shutdown until the temperature goes below the alarm level.
After a shutdown event all stored conversion data are thrown away. Cycling operations (TOUCHRATE > 0) will
resume from the start (i.e. if a 4 channel conversion is stopped during the 3
resuming, the 4 channels will be converted again). If the user was running some manual operation (SELECT,
CONVERT), the corresponding command will have to be re-issued. The haptics operations will resume directly.
Rev 1 – 25
T
touchscreen
EMPERATURE
Warning level: typ. 120° C (TWRNG).
Alarm level: typ. 155° C (TALRM)
th
July 2011
interface
S
ENSOR
running
Figure 50 – Temperature Sensor Overview
(Op.
Mode
Resistive Touchscreen Controller with Proximity Sensing
39
!=
MAN),
SX8654/SX8655/SX8656
proximity
sensing
rd
channel conversion, when
Haptics Enabled 4/5-Wire
interface
www.semtech.com
enabled