參數資料
型號: PIC18F442-E/PT
廠商: Microchip Technology
文件頁數: 119/134頁
文件大小: 0K
描述: IC MCU CMOS 40MHZ 8K FLSH 44TQFP
產品培訓模塊: Asynchronous Stimulus
標準包裝: 160
系列: PIC® 18F
核心處理器: PIC
芯體尺寸: 8-位
速度: 40MHz
連通性: I²C,SPI,UART/USART
外圍設備: 欠壓檢測/復位,LVD,POR,PWM,WDT
輸入/輸出數: 34
程序存儲器容量: 16KB(8K x 16)
程序存儲器類型: 閃存
EEPROM 大小: 256 x 8
RAM 容量: 768 x 8
電壓 - 電源 (Vcc/Vdd): 4.2 V ~ 5.5 V
數據轉換器: A/D 8x10b
振蕩器型: 外部
工作溫度: -40°C ~ 125°C
封裝/外殼: 44-TQFP
包裝: 托盤
1997 Microchip Technology Inc.
DS30444E - page 85
PIC16C9XX
12.4.1
FASTER CONVERSION - LOWER
RESOLUTION TRADE-OFF
Not all applications require a result with 8-bits of reso-
lution, but may instead require a faster conversion time.
The A/D module allows users to make the trade-off of
conversion speed to resolution. Regardless of the res-
olution required, the acquisition time is the same. To
speed up the conversion, the clock source of the A/D
module may be switched so that the TAD time violates
the minimum specied time (see the applicable electri-
cal specication). Once the TAD time violates the mini-
mum specied time, all the following A/D result bits are
not valid (see A/D Conversion Timing in the Electrical
Specications section.) The clock sources may only be
switched between the three oscillator versions (cannot
be switched from/to RC). The equation to determine
the time before the oscillator can be switched is as fol-
lows:
Conversion time = 2TAD + N TAD + (8 - N)(2TOSC)
Where: N = number of bits of resolution required.
Since the TAD is based from the device oscillator, the
user must use some method (a timer, software loop,
etc.) to determine when the A/D oscillator may be
changed. Example 12-3 shows a comparison of time
required for a conversion with 4-bits of resolution, ver-
sus the 8-bit resolution conversion. The example is for
devices operating at 8 MHz (The A/D clock is pro-
grammed for 32TOSC), and assumes that immediately
after 6TAD, the A/D clock is programmed for 2TOSC.
The 2TOSC violates the minimum TAD time, therefore
the last 4-bits will not be converted to correct values.
EXAMPLE 12-3: 4-BIT vs. 8-BIT CONVERSION TIMES
Freq. (MHz)
Resolution
4-bit
8-bit
TAD
8
1.6
s
1.6
s
TOSC
8
12.5 ns
125 ns
2TAD + N TAD + (8 - N)(2TOSC)
8
10.6
s
16
s
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PIC18F442-I/L 功能描述:8位微控制器 -MCU 16KB 768 RAM 34I/O RoHS:否 制造商:Silicon Labs 核心:8051 處理器系列:C8051F39x 數據總線寬度:8 bit 最大時鐘頻率:50 MHz 程序存儲器大小:16 KB 數據 RAM 大小:1 KB 片上 ADC:Yes 工作電源電壓:1.8 V to 3.6 V 工作溫度范圍:- 40 C to + 105 C 封裝 / 箱體:QFN-20 安裝風格:SMD/SMT
PIC18F442-I/L 制造商:Microchip Technology Inc 功能描述:8BIT FLASH MCU SMD 18F442 PLCC44
PIC18F442-I/ML 功能描述:8位微控制器 -MCU 16KB 768 RAM 34I/O RoHS:否 制造商:Silicon Labs 核心:8051 處理器系列:C8051F39x 數據總線寬度:8 bit 最大時鐘頻率:50 MHz 程序存儲器大小:16 KB 數據 RAM 大小:1 KB 片上 ADC:Yes 工作電源電壓:1.8 V to 3.6 V 工作溫度范圍:- 40 C to + 105 C 封裝 / 箱體:QFN-20 安裝風格:SMD/SMT
PIC18F442-I/P 功能描述:8位微控制器 -MCU 16KB 768 RAM 34I/O RoHS:否 制造商:Silicon Labs 核心:8051 處理器系列:C8051F39x 數據總線寬度:8 bit 最大時鐘頻率:50 MHz 程序存儲器大小:16 KB 數據 RAM 大小:1 KB 片上 ADC:Yes 工作電源電壓:1.8 V to 3.6 V 工作溫度范圍:- 40 C to + 105 C 封裝 / 箱體:QFN-20 安裝風格:SMD/SMT
PIC18F442-I/P 制造商:Microchip Technology Inc 功能描述:IC 8BIT FLASH MCU 18F442 DIP40