PCA9505 NXP [NXP Semiconductors], PCA9505 Datasheet - Page 13

• Manufacturer Part Number: PCA9505
• Description: 40-bit I2C-bus I/O port with RESET, OE and INT
• Manufacturer: NXP [NXP Semiconductors]

NXP Semiconductors
PCA9505_9506_3
Product data sheet
7.6 Interrupt output (INT)
7.7 Output enable input (OE)
7.8 Live insertion
7.9 Standby
The open-drain active LOW interrupt is activated when one of the port pins changes state
and the port pin is configured as an input and the interrupt on it is not masked. The
interrupt is deactivated when the port pin input returns to its previous state or the Input
Port register is read.
Remark: Changing an I/O from an output to an input may cause a false interrupt to occur
if the state of the pin does not match the contents of the Input Port register.
Only a read of the Input Port register that contains the bit(s) image of the input(s) that
generated the interrupt clears the interrupt condition.
If more than one input register changed state before a read of the Input Port register is
initiated, the interrupt is cleared when all the input registers containing all the inputs that
changed are read.
Example: If IO0_5, IO2_3, and IO3_7 change state at the same time, the interrupt is
cleared only when INREG0, INREG2, and INREG3 are read.
The active LOW output enable pin allows to enable or disable all the I/Os at the same
time. When a LOW level is applied to the OE pin, all the I/Os configured as outputs are
enabled and the logic value programmed in their respective OP registers is applied to the
pins. When a HIGH level is applied to the OE pin, all the I/Os configured as outputs are
3-stated.
For applications requiring LED blinking with brightness control, this pin can be used to
control the brightness by applying a high frequency PWM signal on the OE pin. LEDs can
be blinked using the Output Port registers and can be dimmed using the PWM signal on
the OE pin thus controlling the brightness by adjusting the duty cycle.
The PCA9505/06 are fully specified for live insertion applications using I
3-states, robust state machine, and 50 ns noise filter. The I
outputs, preventing damaging current backflow through the device when it is powered
down. The power-up 3-state’s circuitry places the outputs in the high-impedance state
during power-up and power-down, which prevents driver conflict and bus contention.
The robust state machine does not respond until it sees a valid START condition and the
50 ns noise filter will filter out any insertion glitches. The PCA9505/06 will not cause
corruption of active data on the bus, nor will the device be damaged or cause damage to
devices already on the bus when similar featured devices are being used.
The PCA9505/06 goes into standby when the I
lower than 1 A (typical).
Rev. 03 — 6 June 2007
40-bit I
2
2
C-bus is idle. Standby supply current is
C-bus I/O port with RESET, OE and INT
OFF
circuitry disables the
PCA9505/06
© NXP B.V. 2007. All rights reserved.
OFF
, power-up
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