PIC16F946 Datasheet, PDF (133/274 Pages) Microchip Technology – 64-Pin Flash-Based, 8-Bit CMOS Microcontrollers with LCD Driver and nanoWatt Technology

PIC16F946
10.0 PROGRAMMABLE
LOW-VOLTAGE DETECT
(PLVD) MODULE
The Programmable Low-Voltage Detect module is an
interrupt driven supply level detection. The voltage
detection monitors the internal power supply.
10.1.1 PLVD CALIBRATION
The PIC16F91X stores the PLVD calibration values in
fuses located in the Calibration Word 2 (2009h). The
Calibration Word 2 is not erased when using the spec-
ified bulk erase sequence in the “PIC16F91X Memory
Programming Specification” (DS41244) and thus, does
not require reprogramming.
10.1 Voltage Trip Points
The PIC16F946 device supports eight internal PLVD
trip points. See Register 10-1 for available PLVD trip
point voltages.
REGISTER 10-1:
LVDCON – LOW-VOLTAGE DETECT CONTROL REGISTER (ADDRESS: 109h)
U-0
U-0
R-0
R/W-0
U-0
R/W-1 R/W-0 R/W-0
—
—
IRVST LVDEN
—
LVDL2 LVDL1 LVDL0
bit 7
bit 0
bit 7-6
bit 5
bit 4
bit 3
bit 2-0
Unimplemented: Read as ‘0’
IRVST: Internal Reference Voltage Stable Status Flag bit⁽¹⁾
1 = Indicates that the PLVD is stable and PLVD interrupt is reliable
0 = Indicates that the PLVD is not stable and PLVD interrupt should not be enabled
LVDEN: Low-Voltage Detect Power Enable bit
1 = Enables PLVD, powers up PLVD circuit and supporting reference circuitry
0 = Disables PLVD, powers down PLVD and supporting circuitry
Unimplemented: Read as ‘0’
LVDL<2:0>: Low-Voltage Detection Limit bits (nominal values)
111 = 4.5V
110 = 4.2V
101 = 4.0V
100 = 2.3V (default)
011 = 2.2V
010 = 2.1V
001 = 2.0V
000 = 1.9V⁽²⁾
Note 1: The IRVST bit is usable only when the HFINTOSC is running. When using an
external crystal to run the microcontroller, the PLVD settling time is expected to be
<50 μs when VDD = 5V and <25 μs when VDD = 3V. Appropriate software delays
should be used after enabling the PLVD module to ensure proper status readings
of the module.
2: Not tested and below minimum VDD.
Legend:
R = Readable bit
- n = Value at POR
W = Writable bit
‘1’ = Bit is set
U = Unimplemented bit, read as ‘0’
‘0’ = Bit is cleared x = Bit is unknown
© 2005 Microchip Technology Inc.
Preliminary
DS41265A-page 131