DM163045 Microchip Technology, DM163045 Datasheet - Page 69

• Manufacturer Part Number: DM163045
• Description: PICDEM Lab Development Kit (with PICkit 3) General Purpose
• Manufacturer: Microchip Technology
• Series: PICDEM™r
• Type: MCUr

Specifications of DM163045

• Contents: Board, PIC kit 3
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant
• For Use With/related Products: PIC Micro® MCU

© 2009 Microchip Technology Inc.
• Fixed 0.6 reference option
• Output clamped to V
The CV
controlled by the CV
Control Register) along with the CV
Selection bits hold a value based upon some simple calculations to set the internal
reference voltage. The CV
EQUATION 4-1:
This lab will implement the low-range calculation by setting the VRR bit in VRCON
equal to 1. Equation 4-2 demonstrates how to calculate the VR<3:0> values, using the
low-range method, to obtain a 2.5V internal reference. If higher resolutions are
required, the high-range method should be used (see Section 8.10.2 in the PIC16F690
Data Sheet (DS-41262).
EQUATION 4-2:
The Initialize() from the previous lab now must configure both the Comparator 1
peripheral and the CV
• Turn on Comparator 1
• Select CV
• Continue to use the C12IN0- pin as the inverting reference
• Turn on CV
• Select the low-range feature
• Set the CV
Changes to the PICDEM™ Development Board configuration schematic for this lab are
shown in Figure 4-3.
VRR = 1 (Low-Range):
Known: desired CV
Therefore:
VRR = 1 (Low-Range):
VRR = 0 (High-Range):
REF
has 2 ranges with 16 voltage levels in each range. Range selection is
REF
REF
REF
the non-inverting reference for Comparator 1
Value Selection bits as per the calculation in Equation 4-2.
REF
CV
REF
CALCULATING A 2.5V INTERNAL REFERENCE
(LOW-RANGE METHOD)
CV
CV
CV
2.5V = (VR<3:0>/24 x 5V
2.5V/5V = (VR<3:0>/24)
(2.5V/5V) x 24 = VR<3:0>
VR<3:0> = 12
REF
SS
REF
Range Selection (VRR) bit in the VRCON (Voltage Reference
= 2.5V, V
REF
REF
REF
as follows:
REF
OUTPUT VOLTAGE
= (VR<3:0>/24) x V
= (V
= (VR<3:0>/24) x V
voltage is determined using Equation 4-1:
Comparator Peripheral Labs
DD
DD
10
REF
/4) + (VR<3:0> x V
approximately 5V
or 1100
Value Selection bits (VR<3:0>). The Value
2
DD
DD
VR0 = 0
VR1 = 0
VR2 = 1
VR3 = 1
DD
/32)
DS41369A-page 65