MCP23S09 Microchip Technology, MCP23S09 Datasheet - Page 9

• Manufacturer Part Number: MCP23S09
• Description: 8-Bit I/O Expander
• Manufacturer: Microchip Technology

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1.4
The ADDR pin is used to set the slave address of the
MCP23009 (I
the bus using only a single pin. Typically, this would
require three pins.
The multi-bit Address Decoder employs a basic FLASH
ADC architecture
generate 8 unique values based on the analog input.
This value is converted to a 3-bit code which
corresponds to the address bits (A2, A1, A0) in the
serial OPCODE.
Sequence
timings):
1.
FIGURE 1-2:
© 2009 Microchip Technology Inc.
Upon power up (after V
becomes active after time t
analog value on the ADDR pin must be stable
before this point to ensure accurate address
assignment.
Multi-bit Address Decoder
of
2
C only) to allow up to eight devices on
R1
R2
V2
(Figure
Operation
V
DD
VOLTAGE DIVIDER EXAMPLE
V
1-4). The seven comparators
SS
DD
ADDR
stabilizes) the module
(see
ADEN
Figure 1-5
. Note, the
V
V
SS
DD
for
MCP23009/MCP23S09
2.
3.
Once the address bits are latched, the device will keep
the slave address until a POR or reset condition
occurs.
1.4.1
When calculating the required voltage on the ADDR pin
(V2), the set point should be the mid-point of the LSb of
the ADC.
The examples in
to determine the mid point voltage (V2) and the range
of voltages based on a voltage divider circuit. The
maximum
recommended to use 5% tolerance worst case (10%
total tolerance).
MCP23009 Only
The 3-bit address is latched after t
The module powers down after the first rising
edge of the serial clock is detected (t
CALCULATING VOLTAGE ON ADDR
tolerance
Figure 1-2
is
and
20%,
A0
A1
A2
Figure 1-3
however,
DS22121B-page 9
ADDRLAT .
ADDIS
show how
).
it
is