MAX7319 Maxim, MAX7319 Datasheet - Page 7

• Manufacturer Part Number: MAX7319
• Description: The MAX7319 2-wire serial-interfaced peripheral features eight input ports with selectable internal pullups, overvoltage protection to +6V, and transition detection with interrupt output
• Manufacturer: Maxim

Table 2. Read and Write Access to Eight-Port Expander Family
of the I
and AD0 that are connected to SDA or SCL normally
appear at power-up to be connected to V+. The pullup
selection logic uses AD0 to select whether pullups are
enabled for ports I3–I0, and uses AD2 to select whether
pullups are enabled for ports I7–I4. The rule is that a
logic-high SDA or SCL connection selects the pullups,
while a logic-low deselects the pullups (Table 3). The
pullup configuration is correct on power-up for a stan-
dard I
up to V+ by the external I
There are circumstances where the assumption that
SDA = SCL = V+ on power-up is not true, for example,
in true hot-swap applications, in which there is legiti-
mate bus activity during power-up. Also, if SDA and
SCL are terminated with pullup resistors to a different
supply voltage than the MAX7319’s supply voltage, and
if that pullup supply rises later than the MAX7319’s sup-
ply, then SDA or SCL may appear at power-up to be
connected to GND. In such applications, use the four
address combinations that are selected by connecting
address inputs AD2 and AD0 to V+ or GND (shown in
bold in Table 3). These selections are guaranteed to be
correct at power-up, independent of SDA and SCL
behavior. If one of the other 12 address combinations is
MAX7319
MAX7320
MAX7321
MAX7322
MAX7323
MAX7328
MAX7329
PART
2
2
C configuration, where SDA and SCL are pulled
C specification. Therefore, address inputs AD2
I
ADDRESS
2
0100xxx
0111xxx
C SLAVE
110xxxx
101xxxx
110xxxx
110xxxx
110xxxx
_______________________________________________________________________________________
I
2
C Port Expander with Eight Inputs and
INPUTS
Up to 8
Up to 4
Up to 8
Up to 8
2
—
C pullup resistors.
8
4
INTERRUPT
MASK
Yes
Yes
—
—
—
—
—
Maskable Transition Detection
OUTPUTS
OPEN-
DRAIN
Up to 8
Up to 4
Up to 8
Up to 8
—
—
—
used, be aware that an unexpected combination of
pullups might be asserted until the first I
sion (to any device, not necessarily the MAX7319) is
put on the bus.
Port inputs switch at CMOS logic levels as determined
by the expander’s supply voltage, and are overvoltage
tolerant to +6V, independent of the expander’s supply
voltage.
All eight input ports are monitored for changes since
the expander was last accessed through the serial
interface. The state of the input ports is stored in an
internal “snapshot” register for transition monitoring.
The snapshot is continuously compared with the actual
input conditions, and if a change is detected for any
port input, an internal transition flag is set for that port.
The eight port inputs are sampled (internally latched
into the snapshot register) and the old transition flags
cleared during the I
read and write access. The previous port transition
flags are read through the serial interface as the sec-
ond byte of a 2-byte read sequence.
OUTPUTS
PUSH-
PULL
—
—
—
—
8
4
4
I
<O7, O6 outputs,
2
<I7–I0 interrupt
<port outputs>
C DATA WRITE
I5–I2 interrupt
mask, O1, O0
<O7–O0 port
<P7–P0 port
<P7–P0 port
<P7–P0 port
Port-Input Transition Detection
outputs>
outputs>
outputs>
outputs>
outputs>
mask>
2
C acknowledge of every MAX7319
<O7, O6, P5–P2, O1, O0 port
<0, 0, P5–P2 transition flags,
<O7, O6, I5–I2, O1, O0 port
<0, 0, I5–I2 transition flags,
<P7–P0 transition flags>
<I7–I0 transition flags>
<O7–O0 port inputs>
<P7–P0 port inputs>
<P7–P0 port inputs>
<P7–P0 port inputs>
<I7–I0 port inputs>
I
2
C DATA READ
inputs>
inputs>
0, 0>
0, 0>
Port Inputs
2
C transmis-
7