PCA9535PW datasheet(17/32 Pages) NXP

17 / 32 page

PCA9535_PCA9535C_3

Product data sheet

Rev. 03 — 4 October 2007

17 of 32

NXP Semiconductors

PCA9535; PCA9535C

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

8.1 Minimizing IDD when the I/Os are used to control LEDs

When the PCA9535 I/Os are used to control LEDs, they are normally connected to VDD

through a resistor as shown in Figure 17. 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.

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 18 shows a high value resistor in parallel with the LED. Figure 19 shows VDD less

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

or above VDD and prevents additional supply current consumption when the LED is off.

This concern does not occur in the case of PCA9535C because the I/O pins are

open-drain.

Limiting values

Fig 18. High value resistor in parallel with

the LED

Fig 19. Device supplied by a lower voltage

002aac189

LED

VDD

LEDn

100 k

Ω

VDD

002aac190

LED

VDD

LEDn

3.3 V

5 V

Table 13.

Limiting values

In accordance with the Absolute Maximum Rating System (IEC 60134).

Symbol

Parameter

Conditions

Min

Max

Unit

VDD

supply voltage

−0.5

+6.0

VI/O

voltage on an input/output pin

VSS − 0.5

output current

on an I/O pin

±50

input current

±20

IDD

supply current

160

ISS

ground supply current

200

Ptot

total power dissipation

200

Tstg

storage temperature

−65

+150

°C

Tamb

ambient temperature

operating

−40

+85

°C

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