PIC16F1847-I/SO Microchip Technology, PIC16F1847-I/SO Datasheet - Page 137

• Manufacturer Part Number: PIC16F1847-I/SO
• Description: 14 KB Flash, 1K Bytes RAM, 32 MHz Int. Osc, 16 I/0, Enhanced Mid Range Core 18 S
• Manufacturer: Microchip Technology

Specifications of PIC16F1847-I/SO

• Lead Free Status / Rohs Status: Lead free / RoHS Compliant

15.0
This family of devices is equipped with a temperature
circuit designed to measure the operating temperature
of the silicon die. The circuit’s range of operating
temperature falls between of -40°C and +85°C. The
output is a voltage that is proportional to the device
temperature. The output of the temperature indicator is
internally connected to the device ADC.
The circuit may be used as a temperature threshold
detector or a more accurate temperature indicator,
depending on the level of calibration performed. A one-
point calibration allows the circuit to indicate a
temperature closely surrounding that point. A two-point
calibration allows the circuit to sense the entire range
of temperature more accurately. Reference Application
Note AN1333, “Use and Calibration of the Internal
Temperature Indicator” (DS01333) for more details
regarding the calibration process.
15.1
Figure 15-1
temperature circuit. The proportional voltage output is
achieved by measuring the forward voltage drop across
multiple silicon junctions.
Equation 15-1
the temperature indicator.
EQUATION 15-1:
The temperature sense circuit is integrated with the
Fixed
Section 14.0 “Fixed Voltage Reference (FVR)”
more information.
The circuit is enabled by setting the TSEN bit of the
FVRCON register
circuit draws no current.
The circuit operates in either high or low range. The high
range, selected by setting the TSRNG bit of the
FVRCON register, provides a wider output voltage. This
provides more resolution over the temperature range,
but may be less consistent from part to part. This range
requires a higher bias voltage to operate and thus, a
higher V
The low range is selected by clearing the TSRNG bit of
the FVRCON register. The low range generates a lower
voltage drop and thus, a lower bias voltage is needed to
operate the circuit. The low range is provided for low
voltage operation.
 2011 Microchip Technology Inc.
Voltage
DD
High Range: V
Low Range: V
TEMPERATURE INDICATOR
MODULE
Circuit Operation
is needed.
shows a simplified block diagram of the
describes the output characteristics of
Reference
(Register
OUT
V
OUT
OUT
= V
= V
14-1). When disabled, the
RANGES
DD
DD
(FVR)
- 2V
- 4V
T
T
module.
See
Preliminary
for
FIGURE 15-1:
15.2
When the temperature circuit is operated in low range,
the device may be operated at any operating voltage
that is within specifications.
When the temperature circuit is operated in high range,
the device operating voltage, V
enough to ensure that the temperature circuit is
correctly biased.
Table 15-1
range setting.
TABLE 15-1:
15.3
The output of the circuit is measured using the internal
Analog-to-Digital Converter. A channel is reserved for
the temperature circuit output. Refer to
“Analog-to-Digital Converter (ADC) Module”
detailed information.
15.4
To ensure accurate temperature measurements, the
user must wait at least 200 s after the ADC input
multiplexer is connected to the temperature indicator
output before the conversion is performed. In addition,
the user must wait 200 s between sequential
conversions of the temperature indicator output.
Min. V
Minimum Operating V
Minimum Sensing Temperature
DD
Temperature Output
ADC Aquisition Time
shows the recommended minimum V
3.6V
, TSRNG = 1
V
PIC16(L)F1847
DD
RECOMMENDED V
RANGE
TEMPERATURE CIRCUIT
DIAGRAM
V
OUT
(ADCON0 register)
TSEN
TSRNG
CHS bits
Min. V
ADC
MUX
n
DD
DS41453A-page 137
DD
, must be high
DD
1.8V
, TSRNG = 0
DD
Section 16.0
vs.
ADC
VS.
DD
vs.
for