PCA9534D 查看數據表（PDF） - Philips Electronics

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PCA9534D

8-bit I2C and SMBus, low power I/O port with interrupt

Philips Electronics 

Philips Semiconductors

8-bit I2C and SMBus low power I/O port with interrupt

Product data sheet

PCA9534

TYPICAL APPLICATION

VDD

(5 V)

VDD

10 kΩ

SCL

MASTER

CONTROLLER

SDA

INT

10 kΩ 10 kΩ 10 kΩ

GND

VDD

2 kΩ

I/O1

INT

I/O2

I/O3

PCA9534

I/O4

I/O5

A2

I/O6

A1

I/O7

A0

100 kΩ

(×3)

INT

RESET

SUBSYSTEM 2

(e.g. counter)

A

ENABLE

Controlled Switch

(e.g. CBT device)

B

VSS

ALARM

SUBSYSTEM 3

(e.g. alarm

system)

NOTE: Device address configured as 0100100 for this example

I/O0, I/O1, I/O2, configured as outputs

I/O3, I/O4, I/O5, configured as inputs

I/O06, I/O7, are not used and have to be configured as outputs

Figure 10. Typical application

VDD

SW2093

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 10. 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 11 shows a high value resistor in parallel with the LED. Figure 12 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 11. High value resistor in parallel with the LED

2004 Sep 30

8

VDD

LEDx

LED

SW02087

Figure 12. Device supplied by a lower voltage

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