mic3002 Micrel Semiconductor, mic3002 Datasheet - Page 27

• Manufacturer Part Number: mic3002
• Description: Mic3002 Fom Management Ic With Internal Calibration
• Manufacturer: Micrel Semiconductor

Micrel, Inc.
July 2007
Power ON and Laser Start-Up
When power is applied, then the MIC3002 initializes its
internal registers and state machine. This process takes
t POR , about 50ms. Following t POR , analog-to-digital
conversions begin, serial communication is possible, and
the POR bit and data ready bits may be polled. The first
set of analog data will be available t CONV after t POR .
MIC3002s are shipped from the factory with the output
enable bit, OE, set to zero, off. The MIC3002’s power-up
default state, therefore, is APC off, V BIAS , V MOD , and
SHDN outputs disabled. V BIAS , V MOD , and SHDN will
be floating (high impedance) and the laser diode, if
connected, will be off. Once the device is incorporated
into a transceiver and properly configured, then the
shutdown states of SHDN, V BIAS and V MOD will be
determined by the state of the APC configuration and
OE bits. Tables 13, 14, and 15 illustrate the shutdown
states of the various laser control outputs versus the
control bits.
Figure 8. V
MOD
Configured as Voltage Output
with Gain
27
In order to facilitate hot-plugging, the laser diode is not
turned on until t
and assuming TXDISABLE is not asserted, the DACs
will be loaded with their initial values. Since t
much less than t
including temperature, is available at t
compensation will be applied to the DAC values if
enabled. APC will begin if OE is asserted. (If the output
enable bit, OE, is not set, the V
outputs will float indefinitely.) Figure 9 shows the power-
up timing of the MIC3002. If TXDISABLE is asserted at
power-up, the V
shutdown states following MIC3002 initialization. A/D
conversions will begin, but the laser will remain off.
OE
OE
0
1
1
0
1
1
Configuration Bits
Configuration Bits
Don’t Care
Don’t Care
Don’t Care
Configuration Bits
Table 13. Shutdown State of SHDN vs.
OE
Table 14. Shutdown State of V
Table 15. Shutdown State of V
0
1
1
INV
Don’t Care
MODREF
MOD
INIT2
0
1
INIT2
Configuration Bits
Configuration Bits
Configuration Bits
[e-mail]
Don’t Care
Don’t Care
BIASREF
and V
SPOL
after Power-On. Following t
, the first set of analog data,
0
1
0
1
BIAS
outputs will stay in their
V
MOD
V
Shutdown State
MOD
BIAS
, V
Shutdown State
INIT2
Shutdown State
SHDN
≈GND
≈V DD
BIAS
MOD
Hi-Z
or [phone]
BIAS
≈GND
≈V DD
M9999-073107-B
≈GND
V
≈V DD
Hi-Z
V
Hi-Z
MOD
. Temperature
BIAS
vs.
vs.
, and SHDN
MIC3002
CONV
INIT2
is
,