MIC3003GFL Datasheet, PDF (27/74 Pages) Micrel Semiconductor – FOM Management IC with Internal Calibration

Micrel, Inc.
Figure 8. V_MOD Configured as Voltage Output
with Gain
Power On and Laser Start-Up
When power is applied, the MIC3003 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.
MIC3003s are shipped from the factory with the output
enable bit, OE, set to zero, off. The 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.
MIC3003GFL
Configuration Bits
OE
SPOL
0
Don’t Care
1
0
1
1
Shutdown State
SHDN
Hi-Z
GND
VDD
Table 13. Shutdown State of SHDN vs.
Configuration Bits
Configuration Bits
OE
INV
BIASREF
0 Don’t Care Don’t Care
1 Don’t Care
0
1 Don’t Care
1
V_BIAS Shutdown State
V_BIAS
Hi-Z
GND
VDD
Table 14. Shutdown State of V_BIAS vs.
Configuration Bits
Configuration Bits
OE
MODREF
0
Don’t Care
1
0
1
1
V_MOD Shutdown State
V_MOD
Hi-Z
GND
VDD
Table 15. Shutdown State of V_MOD vs.
Configuration Bits
In order to facilitate hot-plugging, the laser diode is not
turned on until t_INIT2 after Power-On. Following t_INIT2, and
assuming TXDISABLE is not asserted, the DACs will be
loaded with their initial values. Since tCONV is much less
than t_INIT2, the first set of analog data, including
temperature, is available at t_INIT2. Temperature
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_MOD, V_BIAS, and SHDN
outputs will float indefinitely.) Figure 9 shows the power-
up timing of the MIC3003. If TXDISABLE is asserted at
power-up, the V_MOD and V_BIAS outputs will stay in their
shutdown states following MIC3003 initialization. A/D
conversions will begin, but the laser will remain off.
July 2010
27
M9999-072910-A
[e-mail] or [phone]