PCA9552D datasheet(13/28 Pages) PHILIPS

13 / 28 page

PCA9552_5

Product data sheet

Rev. 05 — 9 March 2006

13 of 28

Philips Semiconductors

PCA9552

16-bit I2C-bus LED driver with programmable blink rates

Application design-in information

8.1 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 15. Since the LED acts as a diode, when the LED is off the I/O

VI is about 1.2 V less than VDD. The supply current, IDD, increases as VI becomes lower

than VDD and is speciﬁed as ∆Istb in Table 13 “Static characteristics”.

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 15 shows a high value resistor in parallel with the LED. Figure 16 shows VDD less

than the LED supply voltage by at least 1.2 V. Both of these methods maintain the

input/output VI at or above VDD and prevents additional supply current consumption when

the LED is off.

LED0 to LED12 are used as LED drivers.

LED13 to LED15 are used as regular GPIOs.

Fig 14. Typical application

PCA9552

LED0

LED1

SDA

SCL

RESET

5 V

I2C-BUS/SMBus

MASTER

002aac188

SDA

SCL

VDD

VSS

5 V

10 k

Ω

×)

LED2

LED3

LED4

LED5

LED6

LED7

LED8

LED9

LED10

LED11

LED12

LED13

LED14

LED15

GPIOs

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