FOA2322A Datasheet, PDF (28/37 Pages) Infineon Technologies AG – 3.2 Gbi t /s Laser Driver IC for Telecom and Datacom Applications

FOA2322A
Pin Description
Table 6
Pin Definitions and Functions (cont’d)
Signal Name Function
Explanation
RST
LEN
LF
CFDEL
COSC
Logic Input
Logic Input
Logic Output
Control
Control
High active reset input. This input resets the LF
indication if present. Further the laser diode is held
within shut down mode if this signal is at low level.
For constant laser diode enable this signal can be
tied to V_EE.
A low level at LEN enables the laser diode, a high
level disables the laser diode. For constant enable
this input can be tied to V_EE.
Fault Indicator. A high level is generated whenever
a fault situation is detected by the supervisor
circuit. Fault situations are laser power failures
indicated by MD input voltage deviation from
V_MDnom. Let open if not used.
With an external capacitor at CFDEL to V_EE the
laser fault detection delay time can be increased.
This means if a constant fault condition is present
a laser fault indication will be generated and the
laser will be shut down after this delay time. The
laser safety circuit can be switched off if CFDEL is
connected to V_CC.
With an external capacitor at COSC to V_EE the
piloton frequency can be decreased (mode 2).
COSC determines the power on delay.
MODE
Logic Input
A high level at MODE sets the modulation control
circuit to mode 1 (using temperature compensation
circuit). A low level at MODE sets the modulation
control circuit to mode 2 (using modulation control
by pilot signal).
RMOD
Control
An external resistor at RMOD to V_EE sets the
modulation current level (in mode 1). Let open if
mode 2 is used.
RTC
Control
An external resistor at RTC to V_EE sets the
modulation current temperature coefficient. The
temperature information is derived from chip
junction temperature (in mode 1). Let open if
mode 2 is used.
Preliminary Data Sheet
24
2001-05