mic3003 Micrel Semiconductor, mic3003 Datasheet - Page 38

• Manufacturer Part Number: mic3003
• Description: Fom Management Ic With Internal Calibration
• Manufacturer: Micrel Semiconductor

Micrel, Inc.
Serial Port Operation
The MIC3003 uses standard write byte, read byte, and
read word operations for communication with its host. It
also supports block write and block read transactions.
The write byte operation involves sending the devices
address (with the R/W bit low to signal a write operation),
followed by the address of the register to be operated
upon and the data byte. The read byte operation is a
composite write and read operation: the host first sends
the devices address followed by the register address, as
in a write operation. A new start bit must then be sent to
the MIC3003, followed by a repeat of the device address
with the R/W bit (LSB) set to the high (read) state. The
data to be read from the part may then be clocked out. A
read word is similar, but two successive data bytes are
clocked out rather than one. These protocols are shown
in Figures 21 to 24.
The MIC3003 will respond to up to four sequential device
addresses depending upon whether it is in OEM or User
mode. A match between one of the MIC3003’s addresses
and the address specified in the serial bit stream must be
made to initiate communication. The MIC3003 responds
to device addresses A0
responds to A4
base address is A0
May 2009
h
and A6
h
).
h
h
and A2
in OEM Mode (assuming the
h
in User Mode; it also
Figure 23. Read_Word Protocol
Figure 21. Write Byte Protocol
Figure 22. Read Byte Protocol
Block Writes
To increase the speed of block writes, the MIC3003 allows
up to eight consecutive bytes to be written before the
internal memory update begins.
The block write sequence begins just like a write byte
operation with the host sending the device address, R/W bit
low, register address, etc. After the first data byte is sent
the host will receive an acknowledge. Up to seven more
bytes can be sent in sequence. The MIC3003 will
acknowledge each one and increment its internal address
register in anticipation of the next byte. After the last byte is
sent, the host issues a STOP. The MIC3003’s internal write
process then begins.
Block writes of up to eight bytes can begin and end at any
byte address without restriction. Block writes that increment
over register address FFh will simply “wrap around” and
continue at address 00h within the same device address
space.
To accelerate calibration and testing, NVRAM write cycles
can be disabled completely by setting the WRINH bit in
OEMCAL0. Writes to registers that do not have NVRAM
backup, will not incur write-cycle delays when writes are
inhibited. Write operations on registers that exist only in
NVRAM will still incur write cycle delays.
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MIC3003