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68HC705JJ7_1 参数 Datasheet PDF下载

68HC705JJ7_1图片预览
型号: 68HC705JJ7_1
PDF下载: 下载PDF文件 查看货源
内容描述: 常规版本规格 [General Release Specification]
分类和应用:
文件页数/大小: 230 页 / 5548 K
品牌: FREESCALE [ Freescale ]
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Freescale Semiconductor, Inc.  
Ana log Sub syste m  
8.8.2 Volta g e Com p a ra tor 2  
Voltage comparator 2 can be used as a simple comparator if its charge  
current source and discharge device are disabled by clearing the ISEN  
bit in the ACR. If the ISEN bit is set, the internal ramp discharge device  
connected to PB0/AN0 may become active and try to pull down any  
voltage source that may be connected to that pin. Also, since voltage  
comparator 2 is always connected to two of the port B I/O pins, these  
pins should be configured as inputs and have their software  
programmable pulldowns disabled.  
8.9 Curre nt Sourc e Fe a ture s  
The internal current source connected to the PB0/AN0 pin supplies  
about 100 µA of current when the discharge device is disabled and the  
current source is active. Therefore, this current source can be used in an  
application if the ISEN enable bit is set to power up the current source  
and by setting the A/D conversion method to manual mode 0 (ATD1 and  
ATD2 cleared) and the charge current enabled (CHG set).  
8.10 Inte rna l Te m p e ra ture Se nsing Diod e Fe a ture s  
An internal diode is forward biased to V and will have its voltage  
SS  
change approximately 2 mV for each degree centigrade rise in the  
temperature of the device. This temperature sensing diode is powered  
up from a current source only during the time that the diode is selected.  
When on, this current source adds about 30 µA to the I current.  
DD  
The temperature sensing diode can be selected by setting both the  
HOLD and DHOLD bits in the AMUX register (see 8.3 Analog Multiplex  
Register).  
8.11 Sa m p le a nd Hold  
When using the internal sample capacitor to capture a voltage for later  
conversion, the HOLD or DHOLD bit must be cleared first before  
changing any channel selection. If both the HOLD (or DHOLD) bit and  
General Release Specification  
MC68HC705JJ7/MC68HC705JP7 Rev. 3.0  
Analog Subsystem  
For More Information On This Product,  
Go to: www.freescale.com  
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