PCA9533D/02 Ver la hoja de datos (PDF) - Philips Electronics

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PCA9533D/02

4-bit I2C LED dimmer

Philips Electronics 

Philips Semiconductors

4-bit I2C LED dimmer

Product data sheet

PCA9533

APPLICATION DATA

5V

5V

SDA

SCL

10 kΩ

10 kΩ

SDA

SCL

VDD

LED0

LED1

LED2

LED3

I2C/SMBus MASTER

VSS

PCA9533

Figure 13. Typical application

SW02047

Minimizing IDD when the I/O is used to control LEDs

When the I/Os are used to control LEDs, they are normally connected to VDD through a resistor as shown in Figure 13. Since the LED acts as a

diode, when the LED is off the I/O VIN is about 1.2 V less than VDD. The supply current, IDD, increases as VIN becomes lower than VDD and is

specified as ∆IDD in the DC characteristics table.

Designs needing to minimize current consumption, such as battery power applications, should consider maintaining the I/O pins greater than or

equal to VDD when the LED is off. Figure 14 shows a high value resistor in parallel with the LED. Figure 15 shows VDD less than the LED supply

voltage by at least 1.2 V. Both of these methods maintain the I/O VIN at or above VDD and prevents additional supply current consumption when

the LED is off.

VDD

3.3 V

5V

VDD

LEDx

LED

100 kΩ

SW02086

Figure 14. High value resistor in parallel with the LED

VDD

LEDx

LED

SW02087

Figure 15. Device supplied by a lower voltage

2004 Oct 01

9

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