Can I use the LBO pin on the MAX1701 to set the CLK/SEL pin low when the battery is low?
Yes, the LBO pin can be used to tell the chip when to go into low power mode. It can be seen from the datasheet that the LBO Output Low Voltage is typically 0.3 to 0.4V. Since the CLK/SEL pins take -0.3V to Vout + 0.3V and Vout ranges from 2.5 to 5.5V, then this is okay.
