PCA6107 Datasheet, PDF (8/24 Pages) Texas Instruments – REMOTE 8-BIT I2C AND SMBus LOW-POWER I/O EXPANDER WITH INTERRUPT OUTPUT, RESET, AND CONFIGURATION REGISTERS

PCA6107
REMOTE 8-BIT I²C AND SMBus LOW-POWER I/O EXPANDER
WITH INTERRUPT OUTPUT, RESET, AND CONFIGURATION REGISTERS
SCPS139B – JANUARY 2006 – REVISED OCTOBER 2006
www.ti.com
Register Descriptions
The Input Port register (register 0) reflects the incoming logic levels of the pins, regardless of whether the pin is
defined as an input or an output by the Configuration register. It acts only on read operation. Writes to these
registers have no effect. The default value, X, is determined by the externally applied logic level. Before a read
operation, a write transmission is sent with the command byte to indicate to the I²C device that the Input Port
register will be accessed next.
BIT
DEFAULT
Register 0 (Input Port Register)
I7
I6
I5
I4
I3
I2
I1
I0
X
X
X
X
X
X
X
X
The Output Port register (register 1) shows the outgoing logic levels of the pins defined as outputs by the
Configuration register. Bit values in this register have no effect on pins defined as inputs. In turn, reads from this
register reflect the value that is in the flip-flop controlling the output selection, not the actual pin value.
BIT
DEFAULT
Register 1 (Output Port Register)
O7
O6
O5
O4
O3
O2
O1
O0
0
0
0
0
0
0
0
0
The Polarity Inversion register (register 2) allows polarity inversion of pins defined as inputs by the Configuration
register. If a bit in this register is set (written with 1), the corresponding port pin's polarity is inverted. If a bit in
this register is cleared (written with a 0), the corresponding port pin's original polarity is retained.
BIT
DEFAULT
Register 2 (Polarity Inversion Register)
N7
N6
N5
N4
N3
N2
N1
N0
1
1
1
1
0
0
0
0
The Configuration register (register 3) configures the directions of the I/O pins. If a bit in this register is set to 1,
the corresponding port pin is enabled as an input with high-impedance output driver. If a bit in this register is
cleared to 0, the corresponding port pin is enabled as an output.
BIT
DEFAULT
Register 3 (Configuration Register)
C7
C6
C5
C4
C3
C2
C1
C0
1
1
1
1
1
1
1
1
Power-On Reset
When power (from 0 V) is applied to V_CC, an internal power-on reset holds the PCA6107 in a reset condition
until V_CC has reached V_POR. At that time, the reset condition is released, and the PCA6107 registers and
I²C/SMBus state machine initializes to their default states. After that, V_CC must be lowered to below 0.2 V and
back up to the operating voltage for a power-reset cycle. The RESET input can be asserted to reset the system,
while keeping the V_CC at its operating level.
RESET Input
A reset can be accomplished by holding the RESET pin low for a minimum of t_W. The PCA6107 registers and
I²C/SMBus state machine are held in their default states until the RESET input is again high. This input requires
a pullup resistor to V_CC, if no active connection is used.
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