VEE是模拟信号的负压轨,也就是模拟信号的范围为Vee~VDD,不能悬空。但目前您的VDD=5V,VEE和VSS接GND是没问题的。
我上面的回复有点儿问题哈,指的是如果模拟信号达到20Vpp的幅值范围的话,那么需要数字信号幅值在4.5V~20V范围,才会有我上面提到的VDD, VSS和VEE之间的关系。
CD405x的datasheet中有这么描述:
Control of analog signals up to 20 VP-P can be achieved by digital signal amplitudes of 4.5 V to 20 V (if VDD – VSS = 3 V, a VDD – VEE of up to 13 V can be controlled; for VDD – VEE level differences above 13 V, a VDD – VSS of at least 4.5 V is required). For example, if VDD = +4.5 V, VSS = 0 V, and VEE = –13.5 V, analog signals from –13.5 V to +4.5 V can be controlled by digital inputs of 0 V to 5 V.