MIC3002_10 Datasheet, PDF (36/65 Pages) Micrel Semiconductor – FOM Management IC with Internal Calibration

Micrel, Inc.
MIC3002
Figure 19. Successfully Clearing a Fault Condition
Figure 20. Unsuccessful Attempt to Clear a Fault
Warm Resets
The MIC3002 can be reset to its power-on default state
during operation by setting the reset bit in OEMCFG0.
When this bit is set, TXFAULT and RXLOS will be de-
asserted, all registers will be restored to their normal
power-on default values, and any A/D conversion in
progress will be halted and the results discarded. The
state of the MIC3002 following this operation is
indistinguishable from a power-on reset.
Power-On Hour Meter
The Power-On Hour meter logs operating hours using an
internal real-time clock and stores the result in NVRAM.
The hour count is incremented at ten-hour intervals in the
middle of each interval. The first increment therefore
takes place five hours after power-on. Time is
accumulated whenever the MIC3002 is powered. The
hour meter’s time base is accurate to 5% over all
MIC3002 operating conditions. The counter is capable of
storing counts of more than thirty years, but is ultimately
limited by the write-cycle endurance of the non-volatile
memory. This implies a range of at least twenty years.
Actual results will depend upon the operating conditions
and write-cycle endurance of the part in question.
Two registers, POHH and POHl, contain a 15-bit power-on
hour measurement and an error flag, POHFLT. Great care
has been taken to make the MIC3002’s hour meter immune
to data corruption and to insure that valid data is maintained
across power cycles. The hour meter employs multiple data
copies and error correction codes to maintain data validity.
This data is stored in the POHDATA registers. If POHFLT is
set, however, the power-on hour meter data has been
corrupted and should be ignored.
It is recommended that a two-byte (or more) sequential
read operation be performed on POHh and POHl to insure
coherency between the two registers. These registers are
accessible by the OEM using a valid OEM password. The
only operation that should be performed on these registers
is to clear the hour meters initial value, if necessary, at the
time of product shipment. The hour meter result may be
cleared by setting all eight POHDATA bytes to 00_h.
Error Flag
Power-On Hour Result Format
High Byte, POHH
Low Byte, POHI
Elapsed Time / 10 Hours, MSBs
Elapsed Time / 10 Hours, LSBs
MSB
LSB
Table 23. Power-On Hour Meter Result Format
July 2007
36
M9999-073107-B
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