SMH4814 Datasheet, PDF (19/44 Pages) Summit Microelectronics, Inc. – Dual Feed Active-ORing Programmable Hot Swap Controller

SMH4814
Preliminary Information
APPLICATIONS INFORMATION (CONTINUED)
Command Register:
The command register (Table 1) provides useful
software functionality for the SMH4814. It is accessed
using the 1001 slave address, and a word address of
0x000. To invoke any of the functions of the
command register, simply write a “1” to the appropriate
bit position. The other bits should receive a “0”. Note
that invoking contradictory commands, such as Power
Down and Power Up, simultaneously will cause
indeterminate results. The following table describes
the command byte:
Status/Fault Registers:
There are three Status/Fault Registers, accessed at
slave address 1001 with address bit A8 set low, at
word address 0x02-0x04. These registers generally
act as status registers, giving the user the current
state of the device. However, when a fault occurs, the
state of the device becomes latched, allowing the user
to access the state of the part at the time of fault.
Once latched into the Fault state, the only way to set
these registers back to Status registers is to use the
command register to clear the fault.
Bit Description
7 Clear Fault
6 Check Fuse
5 Clear WP
4 Set WP
3 Check Short FET
2 Forced Shut Down
1 Power Down
0 Power Up
Table 1 – Command Register
Refer to the Status/Fault Register Tables (page 40) for
more detailed information about the meaning of each
bit.
Serial Interface
The SMH4814 uses the industry standard I²C, 2-wire
serial data interface. This interface provides access to
the general purpose EEPROM, the command and
status registers, and the configuration registers. The
interface has two address inputs A1 and A2
(determined by R0F[7:6]), allowing up to four devices
on the same bus. This allows multiple devices on the
same board or multiple boards in a system to be
controlled with two signals; SDA and SCL.
Device configuration utilizing the Windows based
SMH4814 graphical user interface (GUI) is highly
recommended. The software is available from the
Summit website (www.summitmicro.com/). Using the
GUI in conjunction with this datasheet, simplifies the
process of device prototyping and the interaction of
the various functional blocks. A programming Dongle
(SMX3200) is available from Summit to communicate
with the SMH4814. The Dongle connects directly to
the parallel port of a PC and programs the device
through a cable using the I²C bus protocol.
Summit Microelectronics, Inc
2080 2.0 07/21/05
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