參數(shù)資料
型號(hào)： PIC16F628A
廠商： Microchip Technology Inc.
英文描述： 18-pin Flash-Based 8-Bit CMOS Microcontrollers with nanoWatt Technology(18引腳，基于FLASH的8位CMOS微控制器，使用毫微瓦特技術(shù))
中文描述： 18引腳基于閃存的8位CMOS微控制器與納瓦技術(shù)（18引腳，基于閃存的8位的CMOS微控制器，使用毫微瓦特技術(shù)）
文件頁數(shù)： 100/168頁
文件大?。?/td> 2756K
代理商： PIC16F628A
PIC16F627A/628A/648A
DS40044B-page 98
Preliminary
2004 Microchip Technology Inc.
14.4
Power-on Reset (POR), Power-up
Timer (PWRT), Oscillator Start-up
Timer (OST) and Brown-out Reset
(BOR)
14.4.1
POWER-ON RESET (POR)
The on-chip POR circuit holds the chip in Reset until
V
DD
has reached a high enough level for proper
operation. To take advantage of the POR, just tie the
MCLR pin through a resistor to V
DD
. This will eliminate
external RC components usually needed to create
Power-on Reset. A maximum rise time for V
DD
is
required. See Electrical Specifications for details.
The POR circuit does not produce an internal Reset
when V
DD
declines.
When the device starts normal operation (exits the
Reset
condition), device operating parameters
(voltage, frequency, temperature, etc.) must be met to
ensure operation. If these conditions are not met, the
device must be held in Reset until the operating
conditions are met.
For additional information, refer to Application Note
AN607, “
Power-up Trouble Shooting
”.
14.4.2
POWER-UP TIMER (PWRT)
The PWRT provides a fixed 72 ms (nominal) time out
on power-up (POR) or if enabled from a Brown-out
Reset. The PWRT operates on an internal RC oscilla-
tor. The chip is kept in Reset as long as PWRT is active.
The PWRT delay allows the V
DD
to rise to an accept-
able level. A configuration bit, PWRTE can disable (if
set) or enable (if cleared or programmed) the PWRT. It
is recommended that the PWRT be enabled when
Brown-out Reset is enabled.
The Power-Up Time delay will vary from chip to chip
and due to V
DD
, temperature and process variation.
See DC parameters Table 17-7 for details.
14.4.3
OSCILLATOR START-UP TIMER
(OST)
The OST provides a 1024 oscillator cycle (from OSC1
input) delay after the PWRT delay is over. Program
execution will not start until the OST time out is
complete. This ensures that the crystal oscillator or
resonator has started and stabilized.
The OST time out is invoked only for XT, LP and HS
modes and only on Power-on Reset or wake-up from
Sleep. See Table 17-7.
14.4.4
BROWN-OUT RESET (BOR)
The PIC16F627A/628A/648A have on-chip BOR
circuitry. A configuration bit, BOREN, can disable (if
clear/programmed) or enable (if set) the BOR Reset
circuitry. If V
DD
falls below V
BOR
for longer than T
BOR
,
the brown-out situation will Reset the chip. A Reset is
not guaranteed to occur if V
DD
falls below V
BOR
for
shorter than T
BOR
. V
BOR
and T
BOR
are defined in
Table 17-2 and Table 17-7, respectively.
On any Reset (Power-on, Brown-out, Watchdog, etc.),
the chip will remain in Reset until V
DD
rises above
BV
DD
(see Figure 14-7). The Power-up Timer will now
be invoked, if enabled, and will keep the chip in Reset
an additional 72 ms.
If V
DD
drops below V
BOR
while the Power-up Timer is
running, the chip will go back into a Brown-out Reset
and the Power-up Timer will be re-initialized. Once V
DD
rises above V
BOR
, the Power-Up Timer will execute a
72 ms Reset. Figure 14-7 shows typical Brown-out
situations.
FIGURE 14-7:
BROWN-OUT SITUATIONS WITH PWRT ENABLED
72 ms
V
BOR
V
DD
INTERNAL
RESET
V
BOR
V
DD
INTERNAL
RESET
72 ms
<72 ms
72 ms
V
BOR
V
DD
INTERNAL
RESET
≥
T
BOR
Note:
72 ms delay only if PWRTE bit is programmed to ‘0’.
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相關(guān)代理商/技術(shù)參數(shù)
參數(shù)描述
PIC16F628A-E/ML 功能描述:8位微控制器 -MCU 3.5KB 224 RAM 16 I/O RoHS:否 制造商:Silicon Labs 核心:8051 處理器系列:C8051F39x 數(shù)據(jù)總線寬度:8 bit 最大時(shí)鐘頻率:50 MHz 程序存儲(chǔ)器大小:16 KB 數(shù)據(jù) 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(fēng)格:SMD/SMT
PIC16F628A-E/P 功能描述:8位微控制器 -MCU 3.5KB 224 RAM 16 I/O RoHS:否 制造商:Silicon Labs 核心:8051 處理器系列:C8051F39x 數(shù)據(jù)總線寬度:8 bit 最大時(shí)鐘頻率:50 MHz 程序存儲(chǔ)器大小:16 KB 數(shù)據(jù) 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(fēng)格:SMD/SMT
PIC16F628A-E/SO 功能描述:8位微控制器 -MCU 3.5KB 224 RAM 16 I/O RoHS:否 制造商:Silicon Labs 核心:8051 處理器系列:C8051F39x 數(shù)據(jù)總線寬度:8 bit 最大時(shí)鐘頻率:50 MHz 程序存儲(chǔ)器大小:16 KB 數(shù)據(jù) 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(fēng)格:SMD/SMT
PIC16F628A-E/SS 功能描述:8位微控制器 -MCU 3.5KB 224 RAM 16 I/O RoHS:否 制造商:Silicon Labs 核心:8051 處理器系列:C8051F39x 數(shù)據(jù)總線寬度:8 bit 最大時(shí)鐘頻率:50 MHz 程序存儲(chǔ)器大小:16 KB 數(shù)據(jù) 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(fēng)格:SMD/SMT
PIC16F628A-I/ML 功能描述:8位微控制器 -MCU 3.5KB 224 RAM 16 I/O RoHS:否 制造商:Silicon Labs 核心:8051 處理器系列:C8051F39x 數(shù)據(jù)總線寬度:8 bit 最大時(shí)鐘頻率:50 MHz 程序存儲(chǔ)器大小:16 KB 數(shù)據(jù) 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(fēng)格:SMD/SMT
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