LM3S1637 Luminary Micro, Inc, LM3S1637 Datasheet - Page 415

• Manufacturer Part Number: LM3S1637
• Description: Lm3s1637 Arm Microcontroller
• Manufacturer: Luminary Micro, Inc

16.3
July 25, 2008
Figure 16-3. Comparator Internal Reference Structure
VREF
Table 16-2. Internal Reference Voltage and ACREFCTL Field Values
Initialization and Configuration
The following example shows how to configure an analog comparator to read back its output value
from an internal register.
1.
2.
3.
ACREFCTL Register
EN Bit Value
RNG
EN
EN=0
EN=1
Enable the analog comparator 0 clock by writing a value of 0x0010.0000 to the RCGC1 register
in the System Control module.
In the GPIO module, enable the GPIO port/pin associated with C0- as a GPIO input.
Configure the internal voltage reference to 1.65 V by writing the ACREFCTL register with the
value 0x0000.030C.
AVDD
RNG Bit Value
RNG=X
RNG=0
RNG=1
8R
Output Reference Voltage Based on VREF Field Value
0 V (GND) for any value of VREF; however, it is recommended that RNG=1 and VREF=0
for the least noisy ground reference.
Total resistance in ladder is 31 R.
The range of internal reference in this mode is 0.85-2.448 V.
Total resistance in ladder is 23 R.
The range of internal reference for this mode is 0-2.152 V.
15
R
14
Preliminary
Decoder
R
1
R
0
8R
LM3S1637 Microcontroller
internal
reference
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