MAX7358 Maxim, MAX7358 Datasheet - Page 10

• Manufacturer Part Number: MAX7358
• Description: The MAX7356/MAX7357/MAX7358 8-channel I²C switches/multiplexers expand the main I²C bus to any combination of 8 extended I²C buses
• Manufacturer: Maxim

1-to-8 I
Lock-Up Detection, Isolation, and Notification
The MAX7356/MAX7357/MAX7358 devices are 1-to-8
I
ber of I
connect a main I
ed I
isolate and communicate with devices or groups of
devices that may otherwise have slave address con-
flicts. Any extended bus can be connected or discon-
nected by control packets from the main I
to the main control register of these I
The MAX7357/MAX7358 feature a built-in timer used to
monitor all extended buses, for lock-up conditions. If the
data line of any of these buses is low for more than
25ms, a lock condition is detected. An optional interrupt
can be generated through the bidirectional RST/INT pin.
The master can read the bus lock-up register to find out
which extended bus is locked up. The master can also
optionally enable the MAX7357 or MAX7358 to send a
flush-out sequence on the faulty channel. There is an
optional preconnection check that can be enabled,
which toggles the extended bus clock and data line low
then high to ensure that the downstream bus is not
locked high prior to connecting it to the host bus.
The bus lock-up detection and isolation features are
enabled by writing a unique series of I
the MAX7357/MAX7358.
When power is applied to V
reset (POR) holds the MAX7356/MAX7357/MAX7358 in
a reset state until V
the reset condition is released and the MAX7356/
MAX7357/MAX7358 registers and I
are initialized to their default states.
The MAX7356/MAX7357/MAX7358 feature a basic
mode of operation. In basic mode, the device operates
solely as a collection of analog switches that enable
any combination of the extended buses (SC_, SD_)
to be connected to the host-side bus (SCL, SDA). Only
the switch control register is accessible in basic mode
of operation.
Figure 5. The Special Sequence of I
10
2
C multiplexers/switches for connecting a large num-
2
S
C buses. They enable a master on the main bus to
______________________________________________________________________________________
START
2
ADDRESS OF MUX/SWT PART
C components to a single master. The circuits
ACKNOWLEDGE FROM THE
MAX7357 OR MAX7358
2
2
C bus to any combination of 8 extend-
DD
C Bus Switches/Multiplexers with Bus
Detailed Description
has reached V
Basic Mode of Operation
W
0
A
DD
Sr
2
, an internal power-on
C Commands for Turning on the Full Feature
Power-On Reset
ADDRESS OF MUX/SWT PART
2
C switches.
2
POR
C state machine
2
C commands to
ACKNOWLEDGE FROM THE
2
. At this point,
C bus writing
MAX7357 OR MAX7358
R
1
A
Sr
The MAX7357 and MAX7358 feature an enhanced
mode of operation that enable features and registers
that are unavailable in the basic mode of operation.
When operating in enhanced mode, there are 7 regis-
ters available to the host. Features such as bus lock-up
detection, preconnection fault tests, and diagnostic
information are made available to the user. A special
sequence of commands can switch the MAX7357 or
MAX7358 from basic mode to enhanced mode, and a
simple write to the configuration register can switch the
devices from enhanced mode back to basic mode.
When the 7 registers of Table 2 are enabled, the
MAX7357 and MAX7358 can be put into basic mode by
setting bit B6 of the configuration register. When basic
mode is entered, the value of all registers return to their
POR value. B6 of the configuration register is also main-
tained to allow operation in basic mode. When in basic
mode, the MAX7357 and MAX7358 can be returned to
full feature mode by receiving a special sequence of
commands from the host as described below.
The sequence of I
MAX7357 or MAX7358 enhanced features (bus lock-up
detection, isolation, and notification) as well as access
to the additional 6 registers consists of a write byte, a
read byte, another write byte, and another read byte
with no data bytes following any of these write or read
bytes, as shown in Figure 5. A write byte consists of
the 7-bit MAX7357 or MAX7358 device address fol-
lowed by a 0. A read byte consists of the 7-bit
MAX7357 or MAX7358 device address followed by a 1.
The special sequence begins with a START condition
and ends with a STOP condition. Repeated START
conditions are used to interconnect these write and
read bytes.
The complete special sequence of I
needs to be received by the MAX7357 or MAX7358 to
activate the enhanced mode.
ADDRESS OF MUX/SWT PART
ACKNOWLEDGE FROM THE
MAX7357 OR MAX7358
W
Enhanced Mode of Operation
0
2
A
C commands for enabling the
Entering Basic Mode from
Sr
ADDRESS OF MUX/SWT PART
(MAX7357/MAX7358)
(MAX7357/MAX7358)
ACKNOWLEDGE FROM THE
Enhanced Mode
MAX7357 OR MAX7358
2
C commands
R
1
STOP
A
P