DSP320LF2407的datasheet关于Vccp的说明:
Flash programming voltage pin. This pin must be connected to a 5-V supply for Flash programming. The Flash cannot be programmed if this pin is connected to GND. When not
programming the Flash (i.e., during normal device operation), this pin can either be left connected to the 5-V supply or it can be tied to GND. This pin must not be left floating at any time. Do not use any current-limiting resistor in series with the 5-V supply on this pin. This pin is a “no connect” (NC) on ROM parts and can be left open.
可是为什么常规的时候还是将VCCP引脚接到+5V呢?
Jones Chen:
Is the Vccp pin directly connected to +5V (Do not use any current-limiting resistor in series with the +5V supply on Vccp pin.)? Is the +5V power supply’s output current greater than 500mA current output ability, and output voltage in range between +4.75V and +5.25V? Is +3.3V output voltage for Vdd and Vcca in range between +3.0V and +3.6V?
确认DSP的Vccp脚直接连接到+5V的电源(不要在+5V电源的输出到DSP的Vccp脚间加任何限流电阻),请确认+5电源的电流输出能力大于500毫安,电压输出精度为5%,即电压输出在+4.75~5.25的范围内。请确认+3.3电源的电流输出能力大于250毫安,电压输出精度为10%,即电压输出在+3.0V~+3.6V的范围内。并满足VCP(5V)的精度在+/-5%以内,且VDD(3.3V)先于VCCP(5V)上电。(如下附图)
Note:a. The Flash cannot be programmed if Vccp pin is connected to GND.
b. When not programming the Flash (i.e., during normal device operation), Vccp should be tied to GND. Vccp pin must not be left floating at any time.
c. Do not use any current-limiting resistor in series with the 5-V supply on Vccp pin.
注意!
a. 如果Vccp脚被连接到地(GND), 片上闪存将不能被擦写。
b. 建议Vccp应该被连接到地(GND)当闪存不被擦写时(例如正常运行时)。任何时候Vccp不能悬空,必须连接到+5V或地(GND)。(如下附图)
c. 不要在+5V与Vccp脚之间加任何阻值的限流电阻。