2003 Jun 05 17
Philips Semiconductors Product specification
30 Mbits/s up to 1.25 Gbits/s laser drivers TZA3047A; TZA3047B
12.1.4 ALARM OPERATING CURRENT
The alarm threshold I
oper(alarm)
on the operating current is
determined by the source current I
MAXOP
of the MAXOP
pin. The current range for I
MAXOP
is from 10 to 200 µA
which corresponds with an I
oper(alarm)
from 7.5 to 150 mA.
The I
MAXOP
current can be sunk by an external current
source or by connecting R
MAXOP
to ground:
The operating current equals the bias current for an
AC-coupled laser application and equals the bias current
plus half of the modulation current for the DC-coupled
laser application:
12.1.5 ALARM MONITOR CURRENT
The alarm threshold I
MON(alarm)
on the monitor current is
determined by the source current I
MAXMON
of the
MAXMON pin. The current range for I
MAXMON
is from
10 to 200 µA which corresponds with an I
MON(alarm)
from
150 to 3000 µA. The I
MAXMON
current can be sunk by an
external current source or by connecting R
MAXMON
to
ground:
12.1.6 PULSE WIDTH ADJUSTMENT
The pulse width adjustment time is determined by the
value of resistor R
PWA
, as shown below.
[ps]
The t
PWA
range is from −100 to +100 ps which
corresponds with a R
PWA
range between a minimum
resistance of 6.7 kΩ and a maximum resistance of 20 kΩ.
The PWA function is disabled when the PWA input is
short-circuited to ground; t
PWA
equals 0 ps for a disabled
PWA function.
I
oper(alarm)
N
MAXOP
V
MAXOP
R
MAXOP
--------------------
×=
I
oper TZA3047A()
I
BIAS
=
I
oper TZA3047B()
I
BIAS
I
mod
2
----------
+=
I
MON(alarm)
N
MAXMON
V
MAXMON
R
MAXMON
------------------------
×=
t
PWA
200
R
PWA
10 kΩ–
R
PWA
-------------------------------------
×=
MGT893
handbook, halfpage
R
PWA
(kΩ)
t
PWA
(ps)
100
0
−100
2010
6.7
Fig.6 Pulse width adjustment.
