When the I/Os are used to control LEDs, they are normally connected to V_CC through a resistor as shown in Figure 9-1. The LED acts as a diode, so when the LED is off, the I/O V_IN is about 1.2 V less than V_CC. ΔI_CC in Electrical Characteristics shows how I_CC increases as V_IN becomes lower than V_CC.

For battery-powered applications, it is essential that the voltage of I/O pins is greater than or equal to V_CC when the LED is off to minimize current consumption. Figure 9-2 shows a high-value resistor in parallel with the LED. Figure 9-3 shows V_CC less than the LED supply voltage by at least 1.2 V. Both of these methods maintain the I/O V_IN at or above V_CC and prevent additional supply-current consumption when the LED is off.

Figure 9-2 High-Value Resistor In Parallel With Led

Figure 9-3 Device Supplied By A Lower Voltage