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参数资料
| 型号： | MAX817LEPA+ |
| 厂商： | Maxim Integrated Products |
| 文件页数： | 9/16页 |
| 文件大小： | 0K |
| 描述： | IC SUPERVISOR MPU 5V 8-DIP |
| 产品培训模块： | Lead (SnPb) Finish for COTS Obsolescence Mitigation Program |
| 标准包装： | 50 |
| 类型： | 备用电池电路 |
| 监视电压数目： | 1 |
| 复位： | 低有效 |
| 复位超时： | 最小为 140 ms |
| 电压 - 阀值： | 4.65V |
| 工作温度： | -40°C ~ 85°C |
| 安装类型： | 通孔 |
| 封装/外壳： | 8-DIP（0.300"，7.62mm） |
| 供应商设备封装： | 8-PDIP |
| 包装： | 管件 |
+5V Microprocessor Supervisory Circuits
_______________Detailed Description
General Timing Characteristics
Designed for 5V systems, the MAX817/MAX818/
MAX819 provide a number of microprocessor (μP)
supervisory functions (see the Selector Guide on the
first page). Figure 2 shows the typical timing relation-
ships of the various outputs during power-up and
power-down with typical V CC rise and fall times.
RESET Output
A μP’s reset input starts the μP in a known state. The
MAX817/MAX818/MAX819 μP supervisory circuits
assert a reset to prevent code-execution errors during
power-up, power-down, and brownout conditions.
RESET is guaranteed to be a logic low for 0V < V CC <
V RST if V BATT is greater than 1V. Without a backup bat-
tery (V BATT = GND) RESET is guaranteed valid for
V CC ≥ 1V. Once V CC exceeds the reset threshold an
internal timer keeps RESET low for the reset timeout
period, t RP . After this interval RESET returns high
(Figure 2).
If a brownout condition occurs (V CC drops below the
reset threshold), RESET goes low. Each time RESET is
asserted it stays low for at least the reset timeout peri-
od. Any time V CC goes below the reset threshold the
internal timer clears. The reset timer starts when V CC
returns above the reset threshold. RESET both sources
and sinks current.
Manual Reset Input (MAX819)
Many μP-based products require manual reset capabil-
ity, allowing the operator, a test technician, or external
logic circuitry to initiate a reset. On the MAX819, a logic
low on MR asserts reset. Reset remains asserted while
MR is low, and for t RP (200ms) after it returns high.
During the reset timeout period (t RP ), MR ’s state is
ignored if the battery freshness seal is enabled. MR has
an internal 63k ? pull-up resistor, so it can be left open
if not used. This input can be driven with TTL/CMOS-
logic levels or with open-drain/collector outputs.
Connect a normally open momentary switch from MR to
GND to create a manual reset function; external
debounce circuitry is not required. If MR is driven from
long cables or the device is used in a noisy environ-
ment, connect a 0.1μF capacitor from MR to GND to
provide additional noise immunity.
Note that MR must be high or open to enable the bat-
tery freshness seal. Once the battery freshness seal is
enabled its operation is unaffected by MR .
Battery Freshness Seal
The MAX817/MAX818/MAX819 battery freshness seal
disconnects the backup battery from internal circuitry
and OUT until it is needed. This allows an OEM to
ensure that the backup battery connected to BATT will
be fresh when the final product is put to use. To enable
the freshness seal on the MAX817 and MAX819:
1) Connect a battery to BATT.
2) Ground PFO.
3) Bring V CC above the reset threshold and hold it
there until reset is deasserted following the reset
timeout period.
4) Bring V CC down again (Figure 3).
Use the same procedure for the MAX818, but ground
CE OUT instead of PFO . Once the battery freshness
seal is enabled (disconnecting the backup battery from
internal circuitry and anything connected to OUT), it
remains enabled until V CC is brought above V RST .
V BATT
V RST
V RST
V RST
V RST
V CC
V BATT
V OUT
V BATT
V CC
V RESET
t RP
PFO FOLLOWS PFI
RESET TO
CE OUT
RESET
t RP
DELAY**
V PFO*
V CE OUT**
V BATT
CE OUT (MAX818)
(EXTERNALLY HELD AT 0V)
CE OUT STATE LATCHED
AT 1/2 t RP AND 3/4 t RP ,
FRESHNESS SEAL ENABLED
PFO STATE LATCHED
*MAX817/MAX819 ONLY.
** MAX818 ONLY.
CE OUT FOLLOWS CE IN
PFO (MAX817/MAX819)
(EXTERNALLY HELD AT 0V)
AT 1/2 t RP AND 3/4 t RP ,
FRESHNESS SEAL ENABLED
Figure 2. Power-Up and Power-Down Timing
Figure 3. Battery Freshness Seal Timing
_______________________________________________________________________________________
9
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相关代理商/技术参数 |
参数描述 |
|---|---|
| MAX817LEPA+ | 功能描述:监控电路 5V MPU Supervisor 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 |
| MAX817LESA | 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 |
| MAX817LESA+ | 功能描述:监控电路 5V MPU Supervisor 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 |
| MAX817LESA+T | 功能描述:监控电路 5V MPU Supervisor 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 |
| MAX817LESA-T | 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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