参数资料
型号: AT90S8535-8PI
厂商: Atmel
文件页数: 66/127页
文件大小: 0K
描述: IC MCU 8K FLSH 8MHZ A/D IT 40DIP
标准包装: 18
系列: AVR® 90S
核心处理器: AVR
芯体尺寸: 8-位
速度: 8MHz
连通性: SPI,UART/USART
外围设备: 欠压检测/复位,POR,PWM,WDT
输入/输出数: 32
程序存储器容量: 8KB(4K x 16)
程序存储器类型: 闪存
EEPROM 大小: 512 x 8
RAM 容量: 512 x 8
电压 - 电源 (Vcc/Vdd): 4 V ~ 6 V
数据转换器: A/D 8x10b
振荡器型: 内部
工作温度: -40°C ~ 85°C
封装/外壳: 40-DIP(0.600",15.24mm)
包装: 管件
1997 Microchip Technology Inc.
DS30272A-page 43
PIC16C71X
7.4.1
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
follows:
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 7-3 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 20 MHz and 16 MHz (The A/D
clock is programmed for 32TOSC), and assumes that
immediately after 6TAD, the A/D clock is programmed
for 2TOSC.
The 2TOSC violates the minimum TAD time since the
last 4-bits will not be converted to correct values.
EXAMPLE 7-3:
4-BIT vs. 8-BIT CONVERSION TIMES
Freq. (MHz)(1)
Resolution
4-bit
8-bit
TAD
20
1.6
s
1.6
s
16
2.0
s
2.0
s
TOSC
20
50 ns
16
62.5 ns
2TAD + N TAD + (8 - N)(2TOSC)
20
10
s
16
s
16
12.5
s
20
s
Note 1: The PIC16C71 has a minimum TAD time of 2.0
s.
All other PIC16C71X devices have a minimum TAD time of 1.6
s.
相关PDF资料
PDF描述
AT90USB1287-16AUR IC MCU AVR 128K ISP USB TQFP64
AT90USB162-16AUR IC AVR MCU 16K FLASH 32TQFP
AT91FR40162SB-CU-999 IC MCU 32BIT RISC 121BGA
AT91M40800-33AI SL383 IC ARM MCU 16BIT 100TQFP
AT91M42800A-33CJ IC ARM7 MCU 144 BGA
相关代理商/技术参数
参数描述
AT90SA7-MLTU 功能描述:程序设计器 - 基于通用和内存 ASICS RoHS:否 制造商:Xeltek 产品:Universal Device Programmers 工具用于评估:EPROM, Parallel/Serial EEPROM, FPGA, PROM, Flash, BPROM, MCUs, PLD Devices 接口类型:Parallel, USB 工作电源电压:90 VAC to 250 VAC
AT90SC12036RU 制造商:ATMEL 制造商全称:ATMEL Corporation 功能描述:Secure Microcontroller for Smart Cards
AT90SC128112RU 制造商:ATMEL 制造商全称:ATMEL Corporation 功能描述:Secure Microcontroller for Smart Cards
AT90SC12836RCFT 制造商:ATMEL 制造商全称:ATMEL Corporation 功能描述:Secure Microcontrollers for Smart Cards
AT90SC12836RCFT_07 制造商:ATMEL 制造商全称:ATMEL Corporation 功能描述:Secure Microcontrollers for Smart Cards