欢迎访问ic37.com |
会员登录 免费注册
发布采购

PIC18F25J10-I/SS 参数 Datasheet PDF下载

PIC18F25J10-I/SS图片预览
型号: PIC18F25J10-I/SS
PDF下载: 下载PDF文件 查看货源
内容描述: 28 /40/ 44引脚高性能, RISC微控制器 [28/40/44-Pin High-Performance, RISC Microcontrollers]
分类和应用: 微控制器和处理器外围集成电路光电二极管PC时钟
文件页数/大小: 368 页 / 5652 K
品牌: MICROCHIP [ MICROCHIP ]
 浏览型号PIC18F25J10-I/SS的Datasheet PDF文件第22页浏览型号PIC18F25J10-I/SS的Datasheet PDF文件第23页浏览型号PIC18F25J10-I/SS的Datasheet PDF文件第24页浏览型号PIC18F25J10-I/SS的Datasheet PDF文件第25页浏览型号PIC18F25J10-I/SS的Datasheet PDF文件第27页浏览型号PIC18F25J10-I/SS的Datasheet PDF文件第28页浏览型号PIC18F25J10-I/SS的Datasheet PDF文件第29页浏览型号PIC18F25J10-I/SS的Datasheet PDF文件第30页  
PIC18F45J10 FAMILY  
2.2  
Power Supply Pins  
2.3  
Master Clear (MCLR) Pin  
The MCLR pin provides two specific device  
functions: device Reset, and device programming  
and debugging. If programming and debugging are  
2.2.1  
DECOUPLING CAPACITORS  
The use of decoupling capacitors on every pair of  
power supply pins, such as VDD, VSS, AVDD and  
AVSS, is required.  
not required in the end application,  
a
direct  
connection to VDD may be all that is required. The  
addition of other components, to help increase the  
application’s resistance to spurious Resets from  
Consider the following criteria when using decoupling  
capacitors:  
voltage sags, may be beneficial.  
A
typical  
Value and type of capacitor: A 0.1 μF (100 nF),  
10-20V capacitor is recommended. The capacitor  
should be a low-ESR device with a resonance  
frequency in the range of 200 MHz and higher.  
Ceramic capacitors are recommended.  
configuration is shown in Figure 2-1. Other circuit  
designs may be implemented depending on the  
application’s requirements.  
During programming and debugging, the resistance  
and capacitance that can be added to the pin must  
be considered. Device programmers and debuggers  
drive the MCLR pin. Consequently, specific voltage  
levels (VIH and VIL) and fast signal transitions must  
not be adversely affected. Therefore, specific values  
of R1 and C1 will need to be adjusted based on the  
application and PCB requirements. For example, it is  
recommended that the capacitor, C1, be isolated  
from the MCLR pin during programming and  
debugging operations by using a jumper (Figure 2-2).  
The jumper is replaced for normal run-time  
operations.  
Placement on the printed circuit board: The  
decoupling capacitors should be placed as close  
to the pins as possible. It is recommended to  
place the capacitors on the same side of the  
board as the device. If space is constricted, the  
capacitor can be placed on another layer on the  
PCB using a via; however, ensure that the trace  
length from the pin to the capacitor is no greater  
than 0.25 inch (6 mm).  
Handling high-frequency noise: If the board is  
experiencing high-frequency noise (upward of  
tens of MHz), add a second ceramic type capaci-  
tor in parallel to the above described decoupling  
capacitor. The value of the second capacitor can  
be in the range of 0.01 μF to 0.001 μF. Place this  
second capacitor next to each primary decoupling  
capacitor. In high-speed circuit designs, consider  
implementing a decade pair of capacitances as  
close to the power and ground pins as possible  
(e.g., 0.1 μF in parallel with 0.001 μF).  
Any components associated with the MCLR pin  
should be placed within 0.25 inch (6 mm) of the pin.  
FIGURE 2-2:  
EXAMPLE OF MCLR PIN  
CONNECTIONS  
VDD  
Maximizing performance: On the board layout  
from the power supply circuit, run the power and  
return traces to the decoupling capacitors first,  
and then to the device pins. This ensures that the  
decoupling capacitors are first in the power chain.  
Equally important is to keep the trace length  
between the capacitor and the power pins to  
a minimum, thereby reducing PCB trace  
inductance.  
R1  
R2  
MCLR  
PIC18FXXJXX  
JP  
C1  
Note 1: R1 10 kΩ is recommended. A suggested  
starting value is 10 kΩ. Ensure that the  
MCLR pin VIH and VIL specifications are met.  
2.2.2  
TANK CAPACITORS  
On boards with power traces running longer than six  
inches in length, it is suggested to use a tank capacitor  
for integrated circuits including microcontrollers to  
supply a local power source. The value of the tank  
capacitor should be determined based on the trace  
resistance that connects the power supply source to  
the device and the maximum current drawn by the  
device in the application. In other words, select the tank  
capacitor so that it meets the acceptable voltage sag at  
the device. Typical values range from 4.7 μF to 47 μF.  
2: R2 470Ω will limit any current flowing into  
MCLR from the external capacitor, C, in the  
event of MCLR pin breakdown, due to  
Electrostatic Discharge (ESD) or Electrical  
Overstress (EOS). Ensure that the MCLR pin  
VIH and VIL specifications are met.  
DS39682E-page 24  
© 2009 Microchip Technology Inc.  
 复制成功!