参数资料
型号: MAX795SCSA+T
厂商: Maxim Integrated Products
文件页数: 10/20页
文件大小: 0K
描述: IC SUPERVISOR MPU 8-SOIC
产品培训模块: Lead (SnPb) Finish for COTS
Obsolescence Mitigation Program
标准包装: 2,500
类型: 备用电池电路
监视电压数目: 1
输出: 开路漏极或开路集电极
复位: 低有效
复位超时: 最小为 140 ms
电压 - 阀值: 2.925V
工作温度: 0°C ~ 70°C
安装类型: 表面贴装
封装/外壳: 8-SOIC(0.154",3.90mm 宽)
供应商设备封装: 8-SOIC
包装: 带卷 (TR)
3.0V/3.3V Adjustable Microprocessor
Supervisory Circuits
(OPTIONAL)
3.3V
Si9433DY
SILICONIX
V RST
V RST
0.1 μ F
D
S
PMOS
0.1 μ F
V CC
R1
V CC BATT ON OUT
CMOS
RAM
RESET IN
CE OUT
t RP
R2
MAX794
V CC
RESET
3.6V
0.1 μ F
BATT
CE IN
ADDRESS
DECODER
A0-A15
+5V SUPPLY
+5V FAILURE
WDO
MR
PFO
WDI
LOWLINE
RESET
V CC
4.7k ?
I/O
NMI
RESET
PFO STATE LATCHED,
PFO
FRESHNESS SEAL ENABLED.
(EXTERNALLY HELD AT 0V)
RESET PULLED UP TO V CC
Figure 4. Battery Freshness Seal Enable Timing
PFI
Using the standard application circuit (Figure 3), the
GND
V RST = V RST IN
( R1 R2 + 1 )
reset threshold can be programmed anywhere in the
range of V SW (the battery switch threshold) to 5.5V.
Reset is asserted when V CC falls below V SW .
Figure 3. MAX794 Standard Application Circuit
Reset Threshold
The MAX793T/MAX795T are intended for 3.3V systems
with a ±5% power-supply tolerance and a 10% systems
tolerance. Except when MR is asserted, reset does not
assert as long as the power supply remains above
3.15V (3.3V - 5%). Reset is guaranteed to assert before
the power supply falls below 3.0V (3.3V - 10%).
The MAX793S/MAX795S are designed for 3.3V ±10%
power supplies. Except when MR is asserted, they are
guaranteed not to assert reset as long as the supply
remains above 3.0V (3.0V is just above 3.3V - 10%).
Reset is guaranteed to assert before the power supply
falls below 2.85V (3.3V - 14%).
The MAX793R/MAX795R are optimized to monitor 3.0V
±10% power supplies. Reset does not occur until V CC
falls below 2.7V (3.0V - 10%), but is guaranteed to
occur before the supply falls below 2.55V (3.0V - 15%).
Program the MAX794’s reset threshold with an external
voltage divider to RESET IN. The reset-threshold toler-
ance is a combination of the RESET IN tolerance and
the tolerance of the resistors used to make the external
voltage divider. Calculate the reset threshold as follows:
V RST = V RST IN (R1 / R2 + 1)
Battery Freshness Seal
The MAX793/MAX794’s battery freshness seal discon-
nects the backup battery from internal circuitry until it is
needed. This allows an OEM to ensure that the backup
battery connected to BATT is fresh when the final prod-
uct is put to use. To enable the freshness seal, connect
a battery to BATT, ground PFO , bring V CC above the
reset threshold, and hold it there until reset is deassert-
ed following the reset timeout period, then bring V CC
back down again (Figure 4). Once the battery fresh-
ness seal is enabled (disconnecting the backup battery
from the internal circuitry and anything connected to
OUT), it remains enabled until V CC is brought above
V RST . Note that connecting PFO to MR does not inter-
fere with battery freshness seal operation.
BATT OK Output (MAX793)
BATT OK indicates the status of the backup battery.
When reset is not asserted, the MAX793 checks the
battery voltage continuously. If V BATT is below V BOK
(2.0V min), BATT OK goes low; otherwise, it remains
pulled up to V CC . BATT OK also goes low when V CC
goes below V SW .
Watchdog Input (MAX793/MAX794)
In the MAX793/MAX794, the watchdog circuit monitors
the μP’s activity. If the μP does not toggle the watchdog
input (WDI) within 1.6s, WDO goes low. The internal
1.6s timer is cleared and WDO returns high either when
10
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MAX795SEPA 功能描述:监控电路 RoHS:否 制造商:STMicroelectronics 监测电压数: 监测电压: 欠电压阈值: 过电压阈值: 输出类型:Active Low, Open Drain 人工复位:Resettable 监视器:No Watchdog 电池备用开关:No Backup 上电复位延迟(典型值):10 s 电源电压-最大:5.5 V 最大工作温度:+ 85 C 安装风格:SMD/SMT 封装 / 箱体:UDFN-6 封装:Reel
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MAX795SESA 功能描述:监控电路 RoHS:否 制造商:STMicroelectronics 监测电压数: 监测电压: 欠电压阈值: 过电压阈值: 输出类型:Active Low, Open Drain 人工复位:Resettable 监视器:No Watchdog 电池备用开关:No Backup 上电复位延迟(典型值):10 s 电源电压-最大:5.5 V 最大工作温度:+ 85 C 安装风格:SMD/SMT 封装 / 箱体:UDFN-6 封装:Reel
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