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ASM802LCSAF 参数 Datasheet PDF下载

ASM802LCSAF图片预览
型号: ASM802LCSAF
PDF下载: 下载PDF文件 查看货源
内容描述: 微处理器电源监控器,备用电池切换 [μP Power Supply Supervisor With Battery Backup Switch]
分类和应用: 电池微处理器监控
文件页数/大小: 15 页 / 344 K
品牌: PULSECORE [ PulseCore Semiconductor ]
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ASM690A/692A  
ASM802L/802M  
ASM805L  
April 2008  
rev 1.7  
the ASM692A/802M or within ±10% of 5V for the  
ASM690A/802L/805L to insure that the storage capacitor  
does not achieve an over voltage state.  
Table 2: Maximum Battery Voltages  
Note: SuperCapTM is a trademark of Baknor Industries  
Part Number  
MAXIMUM Battery Voltage (V)  
ASM690A  
ASM802L  
ASM805L  
ASM692A  
ASM802M  
4.80  
4.80  
4.80  
4.55  
4.55  
Although most batteries that meet the requirements of  
Table2 are acceptable, lithium batteries are very effective  
backup source due to their high-energy density and very  
low selfdischarge rates.  
Battery replacement while Powered  
Batteries can be replaced even when the device is in a  
powered state as long as VCC remains above the reset  
threshold voltage VRT. In the ASM devices, a floating  
VBATT pin will not cause a powersupply switchover as can  
occur in some other supervisory circuits. If VBATT is not  
used, the pin should be grounded.  
Backup Power Sources - SuperCap™  
Capacitor storage, with very high values of capacitance,  
can be used as a back-up power source instead of  
batteries. SuperCapare capacitors with capacities in  
the fractional farad range. A 0.1 farad SuperCap™ would  
provide a useful backup power source. Like the battery  
supply, it is important that the capacitor voltage remain  
below the maximum voltages shown in Table 2. Although  
the circuit of Figure 4 shows the most simple way to  
connect the SuperCap™, this circuit cannot insure that an  
over voltage condition will not occur since the capacitor  
will ultimately charge up to VCC. To insure that an over  
voltage condition does not occur, the circuit of Figure 5 is  
preferred. In this circuit configuration, the diode-resistor  
pair clamps the capacitor voltage at one diode drop below  
VCC. VCC itself should be regulated within ±5% of 5V for  
Operation without a Backup Power Source  
When operating without a back-up power source, the  
VBATT pin should be connected to GND and VOUT should  
be connected to VCC, since power source switchover will  
not occur. Connecting VOUT to VCC eliminates the voltage  
drop due to the ON-resistance of the PMOS switch.  
µP Power Supply Supervisor With Battery Backup Switch  
5 of 15  
Notice: The information in this document is subject to change without notice.