L9805E Datasheet, PDF (72/127 Pages) STMicroelectronics – Super smart power motor driver with 8-Bit MCU, RAM, EEPROM, ADC, WDG, Timers, PWM and H-bridge driver

On-Chip Peripherals
L9805E
5.5.6
The sensor generates a voltage proportional to the absolute temperature of the die. It works
over the whole temperature range, with a minimum resolution of 1LSB/°K (5mV/°K)
(Figure 36 shows the indicative voltage output of the sensor).
Note The voltage output of the sensor is only related to the absolute temperature of the
silicon junctions. Junction temperature and ambient temperature must be related taking in
account the power dissipated by the device and the thermal resistance Rth_je between the
silicon and the environment around the application board.
Figure 36. Temperature Sensor output
V_TEMP
2.5
2.2
1.9
max
min
1.6
1.3
1.0
223
273
323
373
423
473
Temperature (°K)
The output of the sensor is not ratiometric with the voltage reference for the ADC conversion
(VCC). When calculating the ADC reading error of this signal the variation of VCC must be
accounted. Additional errors are due to the intrinsic spread of the sensor characteristic.
Precise Temperature Measurement
To allow a more precise measurement of the temperature a trimming procedure can be
adopted (on request).
The temperature is measured in EWS and two values are stored in four EEPROM bytes
(see memory map):
T0L,T0H: temperature of the trimming measurement (in Kelvin).
VT0L,VT0H: output value of the ADC corresponding to T0 (in number of LSBs).
The corrected measurement of the temperature in Kelvin must be accomplished in the
following way:
TEMP (in °K) = VTEMP * T0 / VT0
where VTEMP is the output code in LSB of the ADC corresponding to the measurement.
Example:
If the value stored in EEPROM are:
0C7Ch: 01h ->T0H
0C7Dh: 43h ->T0L
0C7Eh: 01h -> VT0H
0C7Fh: 5Ch -> VT0L
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