- 您現(xiàn)在的位置：買賣IC網(wǎng) > PDF目錄383509 > MAX817MESA (MAXIM INTEGRATED PRODUCTS INC) Dual 4-Input Positive-NAND Gates 14-CDIP PDF資料下載
參數(shù)資料
| 型號： | MAX817MESA |
| 廠商： | MAXIM INTEGRATED PRODUCTS INC |
| 元件分類： | 電源管理 |
| 英文描述： | Dual 4-Input Positive-NAND Gates 14-CDIP |
| 中文描述： | 1-CHANNEL POWER SUPPLY SUPPORT CKT, PDSO8 |
| 封裝： | 0.150 INCH, SOIC-8 |
| 文件頁數(shù)： | 10/16頁 |
| 文件大?。?/td> | 114K |
| 代理商： | MAX817MESA |
M
+5V Mic roproc essor S upervisory Circ uits
10
______________________________________________________________________________________
On the MAX819,
MR
must be high or open to enable
the battery freshness seal. Once the battery freshness
seal is enabled its operation is unaffected by
MR
.
Watc hdog Input (MAX 817/MAX 818)
In the MAX817/MAX818, the watchdog circuit monitors
the μP’s activity. If the μP does not toggle the watchdog
input (WDI) within t
WD
(1.6sec), reset asserts. The inter-
nal 1.6sec timer is cleared by either a reset pulse or by
toggling WDI, which can detect pulses as short as
50ns. The timer remains cleared and does not count for
as long as reset is asserted. As soon as reset is
released, the timer starts counting (Figure 4).
To disable the watchdog function, leave WDI uncon-
nected or three-state the driver connected to WDI. The
watchdog input is internally driven low during the first
7/8 of the watchdog timeout period, then momentarily
pulses high, resetting the watchdog counter. When
WDI is left open-circuited, this internal driver clears the
1.6sec timer every 1.4sec. When WDI is three-stated or
left unconnected, the maximum allowable leakage cur-
rent is 10μA and the maximum allowable load capaci-
tance is 200pF.
Chip-Enable Gating (MAX 818)
Internal gating of the chip-enable (CE) signal prevents
erroneous data from corrupting CMOS RAM in the
event of an undervoltage condition. The MAX818 uses
a series transmission gate from
CE
IN to
CE
OUT
(Figure 5). During normal operation (reset not assert-
ed), the CE transmission gate is enabled and passes
all CE transitions. When reset is asserted, this path
becomes disabled, preventing erroneous data from
corrupting the CMOS RAM. The short CE propagation
delay from
CE
IN to
CE
OUT enables the MAX818 to be
used with most μPs. If
CE
IN is low when reset asserts,
CE
OUT remains low for typically 15μs to permit the
current write cycle to complete.
Chip-Enable Input (MAX 818)
The CE transmission gate is disabled and
CE
IN is high
impedance (disabled mode) while reset is asserted.
During a power-down sequence when V
CC
passes the
reset threshold, the CE transmission gate disables and
CE
IN immediately becomes high impedance if the volt-
age at
CE
IN is high. If
CE
IN is low when reset asserts,
the CE transmission gate will disable 15μs after reset
asserts (Figure 6). This permits the current write cycle
to complete during power-down.
Figure 4. Watchdog Timing
V
CC
t
RP
t
WD
RESET
WDI
Figure 6. Chip-Enable Timing
V
BATT
V
BATT
V
CC
t
RP
t
RP
15
μ
s
V
RST
V
RST
V
RST
V
RST
V
RESET
V
CE IN
V
CE OUT
Figure 5. Chip-Enable Transmission Gate
CE IN
CE OUT
P
N
OUT
CHIP-ENABLE
OUTPUT
CONTROL
RESET
GENERATOR
BATTERY
SWITCHOVER
CIRCUITRY
BATTERY
FRESHNESS
SEAL CIRCUITRY
MAX817
MAX818
相關(guān)PDF資料 |
PDF描述 |
|---|---|
| MAX818L | Dual 4-Input Positive-NAND Gates 14-CFP |
| MAX818LCPA | +5V Microprocessor Supervisory Circuits |
| MAX818LCSA | +5V Microprocessor Supervisory Circuits |
| MAX818LESA | Dual 4-Input Positive-AND Gates 14-CDIP -55 to 125 |
| MAX818M | Dual 4-Input Positive-AND Gates 20-LCCC -55 to 125 |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| MAX817MESA+ | 功能描述:監(jiān)控電路 5V MPU Supervisor RoHS:否 制造商:STMicroelectronics 監(jiān)測電壓數(shù): 監(jiān)測電壓: 欠電壓閾值: 過電壓閾值: 輸出類型:Active Low, Open Drain 人工復(fù)位:Resettable 監(jiān)視器:No Watchdog 電池備用開關(guān):No Backup 上電復(fù)位延遲（典型值）:10 s 電源電壓-最大:5.5 V 最大工作溫度:+ 85 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:UDFN-6 封裝:Reel |
| MAX817MESA+T | 功能描述:監(jiān)控電路 5V MPU Supervisor RoHS:否 制造商:STMicroelectronics 監(jiān)測電壓數(shù): 監(jiān)測電壓: 欠電壓閾值: 過電壓閾值: 輸出類型:Active Low, Open Drain 人工復(fù)位:Resettable 監(jiān)視器:No Watchdog 電池備用開關(guān):No Backup 上電復(fù)位延遲（典型值）:10 s 電源電壓-最大:5.5 V 最大工作溫度:+ 85 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:UDFN-6 封裝:Reel |
| MAX817MESA-T | 功能描述:監(jiān)控電路 RoHS:否 制造商:STMicroelectronics 監(jiān)測電壓數(shù): 監(jiān)測電壓: 欠電壓閾值: 過電壓閾值: 輸出類型:Active Low, Open Drain 人工復(fù)位:Resettable 監(jiān)視器:No Watchdog 電池備用開關(guān):No Backup 上電復(fù)位延遲（典型值）:10 s 電源電壓-最大:5.5 V 最大工作溫度:+ 85 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:UDFN-6 封裝:Reel |
| MAX818_CPA | 制造商:MAXIM 制造商全稱:Maxim Integrated Products 功能描述:+5V Microprocessor Supervisory Circuits |
| MAX818_CSA | 制造商:MAXIM 制造商全稱:Maxim Integrated Products 功能描述:+5V Microprocessor Supervisory Circuits |
發(fā)布緊急采購，3分鐘左右您將得到回復(fù)。