Micrel, Inc.
MIC3003GFL
Pin Number
12
Pin Name
SHDN/TXFIN
Pin Function
Digital output/Input; programmable polarity. When used as shutdown output (SHDN), OEMCFG3
bit 2 set to 0, SHDN is asserted at the detection of a fault condition if OEMCFG4 bit 7 is set to 0. If
OEMCFG4 bit 7 is set to 1, a fault condition will not assert SHDN. When programmed as TXFIN, it
is an input for external fault signals to be OR’ed with the internal fault sources to drive TXFAULT.
Analog Input. Multiplexed A/D input for monitoring laser bias current via a sense resistor (signal
input); accommodates inputs referenced to V
DD
or GND (see pin 14 description).
Analog Input. Reference terminal for the multiplexed pseudo-differential A/D converter inputs for
monitoring laser bias current via a sense resistor (VILD+ is the sensing input). Tie to V
DD
or GND
to reference the voltage sensed on VILD+ to V
DD
or GND, respectively.
Power supply input for analog functions.
Ground return for analog functions.
Analog Input. Multiplexed A/D converter input for monitoring transmitted optical power via a
monitor photodiode. In most applications, VMPD will be connected directly to FB. The input range
is 0 - V
REF
or 0 - V
REF
/4 depending upon the setting of the APC configuration bits
Analog Input. Feedback voltage for the APC loop op-amp. Polarity and scale are programmable
via the APC configuration bits I OEMCFG1. Connect to V
BIAS
if APC is not used.
Analog Output. Buffered DAC output to set the modulation current on the laser driver IC. Operates
with either a 0– V
REF
or a (V
DD
–V
REF
) – V
DD
output swing so as to generate either a ground-
referenced or a V
DD
referenced programmed voltage. A simple external circuit can be used to
generate a programmable current for those drivers that require a current rather than a voltage
input.
Analog input. This pin is the inverting terminal of the VMOD buffer op-amp. Connect to VMOD
(gain = 1) or a feedback resistor network to set a different gain value.
Analog output. Buffered DAC output capable of sourcing or sinking up to 10mA under control of
the APC function to drive an external transistor or the APCSET pin of a laser diode driver for laser
diode DC bias. The output and feedback polarity are programmable to accommodate either an
NPN or a PNP transistor to drive a common-anode or common-cathode laser diode.
Analog output. Compensation terminal for the APC loop. Connect a capacitor between this pin and
GNDA or V
DDA
with the appropriate value to tune the APC loop time constant to a desirable value.
Digital Output. Open-Drain or push-pull.
If OEMCFG3 bit 4 is set to 0, RRSOUT is selected. It represents the receiver rate select as per
SFF. This output is controlled by the SRS0 bit OR’ed with RS0 input and is open drain only.
If OEMCFG3 bit 4 is set to 1, GPO is selected. General-purpose, non-volatile output, it is
controlled by the GPO configuration bits in OEMCFG3.
13
14
VILD+
VILD–
15
16
17
VDDA
GNDA
VMPD
18
19
FB
VMOD
20
21
VMOD–
VBIAS
22
23
COMP
RRSOUT/
GPO
24
RXLOS/
TRSOUT
Digital output. This programmable polarity, open-drain outputs has two purposes:
If OEMCFG6 bit 2 = 0, indicates the loss of the received signal as indicated by a level of received
optical power below the programmed RXLOS comparator threshold; may be wire-OR’ed with
external signals. Normal operation is indicated by a low level when OEMCFG6 bit 3 is set to 0 and
a high level when OEMCFG6 bit 3 is set to 1. RXLOS is de-asserted when VRX > LOSFLTn. The
LOS bit reflects the state of RXLOS whether driven by the MIC3003 or an external circuit.
If OEMCFG6 bit 2 = 1, TRSOUT is selected. This signal represents the transmitter rate select as
per the SFF specification. This output is controlled by the SRS1 bit OR’ed with the RS1 input.
July 2010
9
M9999-072910-A
hbwhelp@micrel.com
or (408) 955-1690
MICREL [ MICREL SEMICONDUCTOR ]
