tza3010b NXP Semiconductors, tza3010b Datasheet - Page 13

• Manufacturer Part Number: tza3010b
• Description: Tza3010b 30 Mbits/s Up To 3.2 Gbits/s A-rate Tm Laser Driver
• Manufacturer: NXP Semiconductors

Philips Semiconductors
12 APPLICATION INFORMATION
12.1
12.1.1
The bias and modulation currents are determined by the
voltages on pins BIASIN and MODIN. For average loop
control the BIASIN voltage is applied by pin BIASOUT and
the MODIN voltage is applied by an external voltage
source or an external resistor R
For direct setting of bias and the modulation current, the
BIASIN and MODIN voltages have to be applied by
external voltage sources or by R
external resistors connected on pins BIASIN and MODIN:
The bias and modulation current sources operate with an
input voltage range from 0.5 to 1.5 V. The output current is
at its minimum level for an input voltage below 0.4 V;
see Figs 3 and 4.
The bias and modulation current sources are temperature
compensated and the adjusted current level remains
stable over the temperature range.
The bias and modulation currents increase with increasing
resistor values for R
allows resistor tuning to start at a minimum current level.
2003 Apr 07
I
I
handbook, halfpage
BIAS
mod
30 Mbits/s up to 3.2 Gbits/s
A-rate
Fig.3 Bias current as a function of BIASIN voltage.
I BIAS
(mA)
=
=
Design equations
110
0.2
B
R
R
0
IAS AND MODULATION CURRENTS
MODIN
BIASIN
I BIAS(min)
laser driver
100 A 0.5 V
100 A 0.5 V
BIASIN
0.5
g m(bias) =
110 mA/V
and R
–
–
MODIN
V BIASIN (V)
BIASIN
MODIN
.
g
g
m(mod)
and R
respectively, this
m(bias)
MODIN
+
1.5
5 mA
MGT890
13
12.1.2
The average monitor current I
source current (I
by an external current source or by an external resistor
(R
I
The average monitor current increases with a decreasing
I
to start at minimum I
The formula used to program AVR is valid for typical
conditions; tuning is necessary to achieve good absolute
accuracy of AVR value.
handbook, halfpage
av(MON)
AVR
I mod = I o(LA)
AVR
LA current when LA output is on.
V
Fig.4
0(LA)
or increasing R
(mA)
) connected to ground:
=
= 1580 A
A
105
VCCO
VERAGE MONITOR CURRENT
Modulation current as a function of MODIN
voltage.
5
0
I o(LA)(min)
AVR
AVR
) of pin AVR. The current can be sunk
AVR
5.26
, this allows resistor tuning of R
0.5
current level (see Fig.5).
g m(mod) =
100 mA/V
V
------------- -
R
av(MON)
AVR
AVR
V MODIN (V)
Product specification
is determined by the
TZA3010B
1.5
MGT891
AVR