参数资料
型号: MC68HC05SB7
厂商: FREESCALE SEMICONDUCTOR INC
元件分类: 微控制器/微处理器
英文描述: 8-BIT, MROM, 2.1 MHz, MICROCONTROLLER, PDSO28
封装: MO-150, SSOP-28
文件页数: 106/170页
文件大小: 2161K
代理商: MC68HC05SB7
GENERAL RELEASE SPECIFICATION
August 27, 1998
MOTOROLA
RESETS
MC68HC05SB7
5-2
REV 2.1
5.1
POWER-ON RESET
A positive transition on the VDD pin generates a power-on reset. The power-on
reset is strictly for conditions during powering up and cannot be used to detect
drops in power supply voltage.
A 4064 tCYC (internal clock cycle) delay after the oscillator becomes active allows
the clock generator to stabilize. If the RESET pin is at logic zero at the end of the
multiple tCYC time, the MCU remains in the reset condition until the signal on the
RESET pin goes to a logic one.
5.2
EXTERNAL RESET
A logic zero applied to the RESET pin for 1.5tCYC generates an external reset.
This pin is connected to a Schmitt trigger input gate to provide and upper and
lower threshold voltage separated by a minimum amount of hysteresis. The exter-
nal reset occurs whenever the RESET pin is pulled below the lower threshold and
remains in reset until the RESET pin rises above the upper threshold. This active
low input will generate the internal RST signal that resets the CPU and peripher-
als.
The RESET pin can also act as an open drain output. It will be pulled to a low
state by an internal pulldown device that is activated by three internal reset
sources. This RESET pulldown device will only be asserted for 3 - 4 cycles of the
internal clock, fOP, or as long as the internal reset source is asserted. When the
external RESET pin is asserted, the pulldown device will not be turned on.
NOTE
Do not connect the RESET pin directly to VDD, as this may overload some power
supply designs when the internal pulldown on the RESET pin activates.
5.3
INTERNAL RESETS
The four internally generated resets are the initial power-on reset function, the
COP Watchdog timer reset, the low voltage reset, and the illegal address detector.
Only the COP Watchdog timer reset, low voltage reset and illegal address detec-
tor will also assert the pulldown device on the RESET pin for the duration of the
reset function or 3 - 4 internal clock cycles, whichever is longer.
5.3.1 Power-On Reset (POR)
The internal POR is generated on power-up to allow the clock oscillator to stabi-
lize. The POR is strictly for power turn-on conditions and is not able to detect a
drop in the power supply voltage (brown-out). There is an oscillator stabilization
delay of 4064 internal processor bus clock cycles after the oscillator becomes
active.
相关PDF资料
PDF描述
MC68HC705SB7 8-BIT, OTPROM, 2.1 MHz, MICROCONTROLLER, PDSO28
MC68HC05SU3AB 8-BIT, MROM, 2 MHz, MICROCONTROLLER, PDIP42
MC68HC05T2P 8-BIT, MROM, MICROCONTROLLER, PDIP40
MC68HC08AS32CFN 8-BIT, EEPROM, 8.4 MHz, MICROCONTROLLER, PQCC52
MC68HC08AS32VFN 8-BIT, EEPROM, 8.4 MHz, MICROCONTROLLER, PQCC52
相关代理商/技术参数
参数描述
MC68HC05SC24 制造商:MOTOROLA 制造商全称:Motorola, Inc 功能描述:Secure 8-bit microcomputer with EEPROM
MC68HC05SR3 制造商:FREESCALE 制造商全称:Freescale Semiconductor, Inc 功能描述:High-density Complementary Metal Oxide Semiconductor (HCMOS) Microcontroller Units
MC68HC05SU3A 制造商:FREESCALE 制造商全称:Freescale Semiconductor, Inc 功能描述:Fully static chip design featuring the industry standard 8-bit M68HC05 core
MC68HC05T16 制造商:FREESCALE 制造商全称:Freescale Semiconductor, Inc 功能描述:High-density complementary metal oxide semiconductor (HCMOS) microcontroller unit
MC68HC05V12 制造商:FREESCALE 制造商全称:Freescale Semiconductor, Inc 功能描述:HCMOS Microcontreller Unit