PCA9535DB datasheet(23/35 Pages) TI

Part #	PCA9535DB

Description	REMOTE 16-BIT I2C AND SMBus, LOW-POWER I/O EXPANDER WITH INTERRUPT OUTPUT AND CONFIGURATION REGISTERS

PDF	35 Pages

Scroll/Zoom	100%

Manufacturer	TI [Texas Instruments]

Direct Link	http://www.ti.com

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Minimizing I

CC When I/O Is Used to Control LED

VCC

LED

100 kW

VCC

3.3 V

5 V

LED

PCA9535

REMOTE 16-BIT I2C AND SMBus, LOW-POWER I/O EXPANDER

WITH INTERRUPT OUTPUT AND CONFIGURATION REGISTERS

SCPS129E – AUGUST 2005 – REVISED FEBRUARY 2007

APPLICATION INFORMATION (continued)

When an I/O is used to control an LED, normally it is connected to VCC through a resistor as shown in Figure 15.

Because the LED acts as a diode, when the LED is off, the I/O VIN is about 1.2 V less than VCC. The ∆ICC

parameter in Electrical Characteristics shows how ICC increases as VIN becomes lower than VCC. For

battery-powered applications, it is essential that the voltage of I/O pins is greater than or equal to VCC, when the

LED is off, to minimize current consumption.

Figure 16 shows a high-value resistor in parallel with the LED. Figure 17 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.

Figure 16. High-Value Resistor in Parallel With LED

Figure 17. Device Supplied by Lower Voltage

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PCA9535DB Datasheet(PDF) 23 Page - Texas Instruments