MIC3001GML Micrel Inc, MIC3001GML Datasheet - Page 19

• Manufacturer Part Number: MIC3001GML
• Description: IC FOM MANAGEMENT W/CALIBR 24MLF
• Manufacturer: Micrel Inc
• Type: Transceiverr

Specifications of MIC3001GML

• Protocol: SDHj Sonet
• Voltage - Supply: 3 V ~ 3.6 V
• Mounting Type: Surface Mount
• Package / Case: 24-MLF®, QFN
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Number Of Drivers/receivers: -
• Other names: 576-1753-5; MIC3001GML

Micrel, Inc.
Internal/External Calibration
The default mode of calibration in the MIC3001 is
external calibration, for which INTCAL bit (bit 0 in
OEMCF3 register) is set to 0. This mode is backward
compatible with MIC3000. The internal calibration mode
is selected by setting INTCAL bit to 1.
A/ External Calibration
The voltage and temperature values returned by the
MIC3001’s A/D converter are internally calibrated. The
binary values of TEMPh:TEMPl and VOLTh:VOLTl are
in the format called for by SFF-8472 under Internal
Calibration.
SFF-8472 calls for a set of calibration constants to be
stored by the transceiver OEM at specific non-volatile
memory locations, refer to SFF-8472 specifications for
memory map of calibration coefficient. The MIC3001
provides the non-volatile memory required for the
storage of these constants. The Digital Diagnostic
Monitoring Interface specification should be consulted for
full details. Slopes and offsets are stored for use with
voltage, temperature, bias current, and transmitted
power measurements. Coefficients for a fourth-order
polynomial are provided for use with received power
measurements. The host system can retrieve these
constants and use them to process the measured data.
Since voltage and temperature require no calibration, the
corresponding slopes should generally be set to unity
and the offsets to zero.
Voltage
The voltage values returned by the MIC3001’s A/D
converter are internally calibrated. The binary values of
VOLTh:VOLTl are in the format called for by SFF-8472
under Internal Calibration. Since VINh:VINl requires no
processing, the corresponding slope should be set to
unity and the offset to zero.
Temperature
The temperature values returned by the MIC3001’s A/D
converter are internally calibrated. The binary values of
TEMPh:TEMPl are in the format called for by SFF-8472
under Internal Calibration. Since TEMPh:TEMPl requires
no processing, the corresponding slope should be set to
unity and the offset to zero.
Bias Current
Bias current is sensed via an external sense resistor as
a voltage appearing at VILD+ and VILD-. The value
returned by the A/D is therefore a voltage analogous to
bias current. Bias current, IBIAS, is simply VVILD/R
The binary value in IBIASh (IBIASl is always zero) is
related to bias current by:
August 2004
SENSE
.
19
The value of the least significant bit (LSB) of IBIASh is
given by:
Per SFF-8472, the value of the bias current LSB is 2µA.
The conversion factor, “slope”, needed is therefore:
The tolerance of the sense resistor directly impacts the
accuracy of the bias current measurement. It is
recommended that the sense resistor chosen be 1%
accurate or better. The offset correction, if needed, can
be determined by shutting down the laser, i.e., asserting
TXDISABLE, and measuring the bias current. Any non-
zero result gives the offset required. The offset will be
equal and opposite to the result of the “zero current”
measurement.
TX Power
Transmit power is sensed via an external sense resistor
as a voltage appearing at VMPD. It is assumed that this
voltage is generated by a sense resistor carrying the
monitor photodiode current. In most applications, the
signal at VMPD will be feedback voltage on FB. The
VMPD voltage may be measured relative to GND or
V
OEMCFG1. The value returned by the A/D is therefore a
voltage analogous to transmit power. The binary value in
TXOPh (TXOPl is always zero) is related to transmit
power by:
For a given implementation, the value of RSENSE is
known. It is either the value of the external resistor or the
chosen value of RFB used in the application. The
constant, K, will likely have to be determined through
experimentation or closed-loop calibration, as it depends
on the monitoring photodiode responsivity and coupling
efficiency.
It should be noted that the APC circuit acts to hold the
transmitted power constant. The value of transmit power
reported by the circuit should only vary by a small
amount as long as APC is functioning correctly.
DDA
depending on the setting of the BIASREF bit in
[e-mail]
or [phone]
M9999-082404-A
MIC3001
(3)
(1)
(2)