MIC3000_07 datasheet(30/68 Pages) MICREL

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MIC3000

Micrel

M9999-101204

October 2004

Warm Resets

The MIC3000 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 deasserted, 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 MIC3000 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

MIC3000 is powered. The hour meter’s timebase is accurate

to 5% over all MIC3000 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.

Power-On Hour Result Format

High Byte, POHH

Low Byte, POHl

Error flag

Elapsed Time / 10 Hours, MSB’s

Elapsed Time / 10 Hours, LSB’s

MSB

LSB

Table 18. Power-On Hour Meter Result Format

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

OEMCAL0

(temperature compensation not used)

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 19. Test and Diagnostic Features

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 MIC3000’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 cor-

rupted and should be ignored.

It is recommended that a two-byte (or more) sequential read

operation be performed on POHh and POHl to insure coher-

ency between the two registers. These registers are acces-

sible 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.

Test and Calibration Features

Numerous features are included in the MIC3000 to facilitate

development, testing, and diagnostics. These features are

available via registers in the OEM area. As shown in Table19,

these features include:

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