Micrel, Inc.
MIC3001
August 2004
35
M9999-082404-A
Warm Resets
The MIC3001 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
MIC3001
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 MIC3001 is powered. The
hour meter’s timebase is accurate to 5% over all MIC3001
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 on 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 MIC3001’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 00h.
Power-On Hour Result Format
High Byte, POHH
Low Byte, POHI
Error Flag
Elapsed Time / 10 Hours, MSBs
Elapsed Time / 10 Hours, LSBs
MSB
LSB
Table 20. Power-On Hour Meter Result Format
Test and Calibration Features
Numerous features are included in the MIC3001 to
facilitate development, testing, and diagnostics. These
features are available via registers in the OEM area. As
shown
in
Table
21,
these
features
include:
Function
Description
Control
Register(s)
Analog loop-back
Provides analog visibility of op-amp and DAC outputs via the ADC
OEMCFG0
Fault comparator disable control
Disables the fault comparator
OEMCAL0
Fault comparator spin-on-channel mode
Selects a single fault comparator channel
OEMCAL0
Fault comparator output read-back
Allows host to read individual fault comparator outputs
OEMRD
RSOUT, /INT read-back
Allows host to read the state of these pins
OEMRD
Inhibit EEPROM write cycles
Speeds repetitive writes to registers backed up by NVRAM
OEMCAL0
APC calibration mode
Allows direct writes to MODDAC and APCDAC (temperature
compensation not used)
OEMCAL0
Continuity checking
Forcing of RXLOS, TXFAULT, /INT
OEMCAL0
Halt A/D
Stops A/D conversions; ADC in one-shot mode
OEMCAL1
ADC idle flag
Indicates ADC status
OEMCAL1
A/D one-shot mode
Performs a single A/D conversion on the selected input channel
OEMCAL1
A/D spin-on-channel mode
Selects a single input channel
OEMCAL1
Channel selection
Selects ADC or fault comparator channel for spin-on-channel modes
OEMCAL1
LUT index read-back
Permits visibility of the LUT index calculated by the state-machine
LUTINDX
Manufacturer and device ID registers
Facilitates presence detection and version control
MFG_ID, DEV_ID
Table 21. Test and Diagnostic Features