iC-NZP
P-TYPE LASER DIODE DRIVER
nar y
limi
pre
Rev A1, Page 7/13
DESCRIPTION OF FUNCTIONS
iC-NZP is a laser diode pulse driver, which features:
• Averaging or peak control
• Optical power or current control
• Laser current limitation
• Pulses of up to 155 MHz in controlled
burst mode
• Sleep mode with less than 50 µA consumption
• Extension of the laser current with few external com-
ponents
• Error signalling for overcurrent
OPTICAL POWER CONTROL
The iC-NZP supports the control of the laser diode’s
optical output power (APC) for all common laser diode
pin configurations (P, N and M). The control is enabled
with pin REGE set to high. With AVG set to low, the
peak power control is enabled. The laser power level
is selected by means of the resistor RMON (= RMD +
PMD). This control mode can be used for frequencies
up to ca. 4 Mhz. For higher frequencies the averag-
ing control (AVG = high) or the
burst mode
have to be
used.
Tables 4 and 5 show how to set the inputs for laser
control depending on the input interface selected (TTL
or LVDS).
Laser control in TTL mode (TTL = high/open)
EP
EN
NSLP
REGE
SYN Mode
-
-
low/open -
-
Power-save mode
low/open open high
-
low VDDA charged, laser off
high
open high
high/open high VDDA charged, laser on, regulated
high
open high
low
high VDDA charged, laser on, burst mode
Table 4: Laser control in TTL mode
Laser control in LVDS mode (TTL = low)
EP
EN
NSLP
REGE
SYN
-
-
low/open -
-
< EN > EP high
-
low
> EN < EP high
high/open high
> EN < EP high
low
high
Mode
Power-save mode
VDDA charged, laser off
VDDA charged, laser on, regulated
VDDA charged, laser on, burst mode
Table 5: Laser control in LVDS mode
RMON dimensioning
Peak control (AVG = low): In order to calculate the right
value of RMON, the value of
IM
(monitor current with
respect to optical output power) of the laser diode must
be known. RMON must be chosen in a way that the
monitor current generated by the desired output power
creates a voltage drop across RMON of 250 mV (cf.
Electrical Characteristics No. 201).
Averaging control (AVG = high): In this mode the cal-
culation is the same as in peak control, only the result
has to be divided by the duty cycle of the laser pulses,
1
τ
D
=
T
. At a duty cycle of e.g. 50%
D
=
2
.
ICHAUS [ IC-HAUS GMBH ]
