Datasheet

PIC16C77X
 1999-2013 Microchip Technology Inc. Advance Information DS30275B-page 113
10.0 VOLTAGE REFERENCE
MODULE AND LOW-VOLTAGE
DETECT
The Voltage Reference module provides reference volt-
ages for the Brown-out Reset circuitry, the Low-voltage
Detect circuitry and the A/D converter.
The source for the reference voltages comes from the
bandgap reference circuit. The bandgap circuit is ener-
gized anytime the reference voltage is required by the
other sub-modules, and is powered down when not in
use. The control registers for this module are LVDCON
and REFCON, as shown in Figure 10-1 and
Figure 10-2.
FIGURE 10-1: LVDCON: LOW-VOLTAGE DETECT CONTROL REGISTER
U-0 U-0 R-0 R/W-0 R/W-0 R/W-1 R/W-0 R/W-1
— — BGST LVDEN LV3 LV2 LV1 LV0 R = Readable bit
W = Writable bit
U = Unimplemented bit,
read as ‘0’
- n =Value at POR reset
bit7 bit0
bit 7-6: Unimplemented: Read as '0'
bit 5: BGST: Bandgap Stable Status Flag bit
1 = Indicates that the bandgap voltage is stable, and LVD interrupt is reliable
0 = Indicates that the bandgap voltage is not stable, and LVD interrupt should not be enabled
bit 4: LV D E N: Low-voltage Detect Power Enable bit
1 = Enables LVD, powers up bandgap circuit and reference generator
0 = Disables LVD, powers down bandgap circuit if unused by BOR or VRH/VRL
bit 3-0: LV3 : LV 0: Low Voltage Detection Limit bits
(1)
1111 = External analog input is used
1110 = 4.5V
1101 = 4.2V
1100 = 4.0V
1011 = 3.8V
1010 = 3.6V
1001 = 3.5V
1000 = 3.3V
0111 = 3.0V
0110 = 2.8V
0101 = 2.7V
0100 = 2.5V
Note 1: These are the minimum trip points for the LVD, see Table 15-3 for the trip point tolerances. Selection
of an unused setting may result in an inadvertant interrupt.
774.book Page 113 Tuesday, January 29, 2013 12:02 PM