SCPS193D July 2010 – January 2023 TCA6424A
PRODUCTION DATA
When the I/Os are used to control LEDs, normally they are connected to VCC through a resistor as shown in Figure 9-1. The LED acts as a diode so, when the LED is off, the I/O VIN is about 1.2 V less than VCC. The ΔICC parameter in Electrical Characteristics shows how ICC increases as VIN becomes lower than VCC. Designs that must minimize current consumption, such as battery power applications, should consider maintaining the I/O pins greater than or equal to VCC when the LED is off.
Figure 9-2 shows a high-value resistor in parallel with the LED. Figure 9-3 shows VCC less than the LED supply voltage by at least 1.2 V. Both of these methods maintain the I/O VIN at or above VCC and prevent additional supply current consumption when the LED is off.