Datasheet

PCA9535_PCA9535C_5 © NXP B.V. 2008. All rights reserved.
Product data sheet Rev. 05 — 15 September 2008 17 of 31
NXP Semiconductors
PCA9535; PCA9535C
16-bit I
2
C-bus and SMBus, low power I/O port with interrupt
8.1 Minimizing I
DD
when the I/Os are used to control LEDs
When the PCA9535 I/Os are used to control LEDs, they are normally connected to V
DD
through a resistor as shown in Figure 17. Since the LED acts as a diode, when the LED is
off the I/O V
I
is about 1.2 V less than V
DD
. The supply current, I
DD
, increases as V
I
becomes lower than V
DD
.
Designs needing to minimize current consumption, such as battery power applications,
should consider maintaining the I/O pins greater than or equal to V
DD
when the LED is off.
Figure 18 shows a high value resistor in parallel with the LED. Figure 19 shows V
DD
less
than the LED supply voltage by at least 1.2 V. Both of these methods maintain the I/O V
I
at
or above V
DD
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.
9. Limiting values
Fig 18. High value resistor in parallel with
the LED
Fig 19. Device supplied by a lower voltage
002aac189
LED
V
DD
LEDn
100 kΩ
V
DD
002aac190
LED
V
DD
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
V
DD
supply voltage −0.5 +6.0 V
V
I/O
voltage on an input/output pin V
SS
− 0.5 6 V
I
O
output current on an I/O pin - ±50 mA
I
I
input current - ±20 mA
I
DD
supply current - 160 mA
I
SS
ground supply current - 200 mA
P
tot
total power dissipation - 200 mW
T
stg
storage temperature −65 +150 °C
T
amb
ambient temperature operating −40 +85 °C