PIC24FJ64GA705 Datasheet, PDF (320/412 Pages) –

PIC24FJ256GA705 FAMILY
27.4 Measuring Die Temperature
The CTMU can be configured to use the A/D to
measure the die temperature using dedicated A/D
Channel 24. Perform the following steps to measure
the diode voltage:
• The internal current source must be set for either
5.5 µA (IRNG<1:0> = 0x2) or 55 µA
(IRNG<1:0> = 0x3).
• In order to route the current source to the diode,
the EDG1STAT and EDG2STAT bits must be
equal (either both ‘0’ or both ‘1’).
• The CTMREQ bit (AD1CON5<13>) must be set
to ‘1’.
• The A/D Channel Select bits must be 24 (0x18)
using a single-ended measurement.
The voltage of the diode will vary over temperature
according to the graphs shown below (Figure 27-4). Note
that the graphs are different, based on the magnitude of
the current source selected. The slopes are nearly linear
over the range of -40ºC to +100ºC and the temperature
can be calculated as follows:
EQUATION 27-2:
For 5.5 µA Current Source:
Tdie = ^{710 mV – Vdiode}
1.8
where Vdiode is in mV, Tdie is in ºC
For 55 µA Current Source:
Tdie = ^{760 mV – Vdiode}
1.55
where Vdiode is in mV, Tdie is in ºC
FIGURE 27-4:
850
825
800
775
750
725
700
675
650
625
600
575
550
525
500
475
450
-40
DIODE VOLTAGE (mV) vs. DIE TEMPERATURE (TYPICAL)
-20
0
20
40
60
Die Temperature (°C)
80
100
120
5₅._.5_5UµA_A
5₅5_5UµA_A
DS30010118B-page 320
 2016 Microchip Technology Inc.