参数资料
| 型号： | DS1238A-10 |
| 厂商： | Maxim Integrated Products |
| 文件页数： | 7/13页 |
| 文件大小： | 0K |
| 描述： | IC MICROMANAGER 10% 16-DIP |
| 标准包装： | 25 |
| 系列： | MicroManager |
| 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： | 高有效/低有效 |
| 复位超时： | 最小为 40 ms |
| 电压 - 阀值： | 4.37V |
| 工作温度： | 0°C ~ 70°C |
| 安装类型： | 通孔 |
| 封装/外壳： | 16-DIP（0.300"，7.62mm） |
| 供应商设备封装： | 16-PDIP |
| 包装： | 管件 |
DS1238A
MEMORY BACKUP
The DS1238A provides all of the necessary functions required to battery back a static RAM. First, an
internal switch is provided to supply SRAM power from the primary 5-volt supply (V CC ) or from an
external battery (V BAT ), whichever is greater. Second, the s am e power-fail detection described in the
power monitor section is used to hold the chip enable output ( CEO ) to within 0.3 volts of V CC or to within
0.7 volts of V BAT . The output voltage diode drop from V BAT (0.7V) is necessary to prevent charging of the
battery in violation of UL standards. Write protection occurs as V CC falls below V CCTP as specified. If
CEI is low at the time power-fail detection occurs, CEO is held in its present state until CEI is returned
high, or the period t CE expires. This delay of write protection until the current memory cycle is completed
prevents the corruption of data. If CEO is in an inactive state at the time of V CC fail detection, CEO will
be unconditionally disabled within t CF . During nominal supply conditions CEO will follow CEI with a
maximum propagation delay of 20 ns. NO TAG shows a typical nonvolatile SRAM application.
FRESHNESS SEAL
In order to conserve battery capacity during initial construction of an end system, the DS1238A provides
a freshness seal that electrically disconnects the battery. This means that upon battery attachment, the
V CCO output will remain inactive until V CC is applied. This prevents V CCO from powering other devices
when the battery is first attached, and V CC is not present. Once V CC is applied, the freshness seal is broken
and cannot be invoked again without subsequent removal and reattachment of the battery.
POWER SWITCHING
When larger operating currents are required in a battery-backed system, the internal switching devices of
the DS1238A may be too small to support the required load through V CCO with a reasonable voltage drop.
For these applications, the PF output is provided to gate external power switching devices. As shown in
Figure 8, power to the load is switched from V CC to battery on power-down, and from battery to V CC on
power-up. The DS1336 is designed to use the PF output to switch between V BAT and V CC . It provides
better leakage and switchover performance than currently available discrete components. The transition
threshold for PF is set to the external battery voltage V BAT , allowing a smooth transition between sources.
Any load applied to the PF pin by an external switch will be supplied by the battery. Therefore, if a
discrete switch is used, this load should be taken into consideration when sizing the battery.
NONVOLATILE SRAM Figure 7
7 of 13
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相关代理商/技术参数 |
参数描述 |
|---|---|
| DS1238A-10+ | 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 |
| DS1238A10N | 制造商:未知厂家 制造商全称:未知厂家 功能描述:Analog IC |
| DS1238A-10N | 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 |
| DS1238A-10N+ | 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 |
| DS1238A-5 | 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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