PIC18F2520-I/SO Microchip Technology Inc., PIC18F2520-I/SO Datasheet - Page 248

• Manufacturer Part Number: PIC18F2520-I/SO
• Description: 28 Pin, 32 KB Flash, 1536 RAM, 25 I/O
• Manufacturer: Microchip Technology Inc.

Specifications of PIC18F2520-I/SO

• A/d Inputs: 10-Channel, 10-Bit
• Comparators: 2
• Cpu Speed: 10 MIPS
• Eeprom Memory: 256 Bytes
• Input Output: 25
• Interface: I2C/SPI/USART
• Memory Type: Flash
• Number Of Bits: 8
• Package Type: 28-pin SOIC
• Programmable Memory: 32K Bytes
• Ram Size: 1.5K Bytes
• Speed: 40 MHz
• Timers: 1-8-bit, 3-16-bit
• Voltage, Range: 2-5.5 V
• Lead Free Status / Rohs Status: RoHS Compliant part Electrostatic Device

PIC18F2420/2520/4420/4520
FIGURE 22-3:
22.5
In many applications, the ability to detect a drop below
or rise above a particular threshold is desirable. For
example, the HLVD module could be periodically
enabled to detect Universal Serial Bus (USB) attach or
detach. This assumes the device is powered by a lower
voltage source than the USB when detached. An attach
would indicate a high-voltage detect from, for example,
3.3V to 5V (the voltage on USB) and vice versa for a
detach. This feature could save a design a few extra
components and an attach signal (input pin).
For general battery applications, Figure 22-4 shows a
possible voltage curve. Over time, the device voltage
decreases. When the device voltage reaches voltage
V
The interrupt could cause the execution of an ISR,
which would allow the application to perform “house-
keeping tasks” and perform a controlled shutdown
before the device voltage exits the valid operating
range at T
tion a time window, represented by the difference
between T
DS39631A-page 246
A
, the HLVD logic generates an interrupt at time T
CASE 1:
CASE 2:
Enable HLVD
Enable HLVD
Applications
A
B
. The HLVD, thus, would give the applica-
and T
HLVDIF
HLVDIF
IRVST
IRVST
V
V
B
DD
DD
, to safely exit.
HIGH-VOLTAGE DETECT OPERATION (VDIRMAG =
HLVDIF may not be set
Internal Reference is stable
Internal Reference is stable
T
T
IVRST
IVRST
A
.
HLVDIF cleared in software,
HLVDIF remains set since HLVD condition still exists
FIGURE 22-4:
V
V
A
B
Legend:
HLVDIF cleared in software
V
V
A
B
1
= HLVD trip point
= Minimum valid device
)
TYPICAL LOW-VOLTAGE
DETECT APPLICATION
 2004 Microchip Technology Inc.
operating voltage
Time
HLVDIF cleared in software
T
A
V
V
LVD
LVD
T
B