MAX1233_05 Datasheet, PDF (33/45 Pages) Maxim Integrated Products – ±15kV ESD-Protected Touch-Screen Controllers Include DAC and Keypad Controller

±15kV ESD-Protected Touch-Screen
Controllers Include DAC and Keypad Controller
HOST WRITES
ADC
CONTROL REGISTER
START CLOCK
SET BUSY
LOW
TEMPERATURE INPUT 1
HOST WRITES
ADC
CONTROL REGISTER
START CLOCK
SET BUSY
LOW
TEMPERATURE INPUT 1
AND TEMPERATURE INPUT 2
CONVERT
TEMPERATURE INPUT 2
IS ADC
NO
REFERENCE IN
AUTO POWER-DOWN
MODE?
YES
POWER UP REFERENCE
POWER UP
ADC
CONVERT
TEMPERATURE INPUT 1
NO
IS DATA
AVERAGING DONE?
YES
STORE TEMPERATURE INPUT 1 IN
TEMP1 REGISTER
POWER DOWN
ADC
POWER DOWN REFERENCE
SET BUSY HIGH
TURN OFF CLOCK
DONE
IS ADC
NO
REFERENCE IN
AUTO POWER-DOWN
MODE?
YES
POWER UP REFERENCE
POWER UP
ADC
CONVERT
TEMPERATURE INPUT 1
NO
IS DATA
AVERAGING DONE?
YES
STORE TEMPERATURE INPUT 2 IN
TEMP2 REGISTER
POWER DOWN
ADC
POWER DOWN REFERENCE
NO
IS DATA
AVERAGING DONE?
YES
STORE TEMPERATURE INPUT 1 IN
TEMP1 REGISTER
SET BUSY HIGH
TURN OFF CLOCK
DONE
Figure 18. Single Temperature Measurement Process
where:
∆V = V (I N) - V (I1) (in mV)
T(°K) = 2.68(°K/mV) × ∆V(mV)
T(°C) = [2.68(°K/mV) × ∆V(mV) - 273°K]°C/ °K
This differential conversion method does not require a
test temperature calibration and can provide much
improved absolute temperature measurement. In the
differential conversion method, however, the resolution
Figure 19. Differential Temperature Measurement Process
is 1.6°C/LSB (2.5V reference) and 0.65°C/LSB (1V ref-
erence) with a typical accuracy of ±3°C. Figure 19
shows the differential temperature measurement-
process.
Note: The bias current for each diode temperature
measurement is only turned ON during the acquisition
and, therefore, does not noticeably increase power
consumption.
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