tza3010b NXP Semiconductors, tza3010b Datasheet - Page 7

• 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
7.5
The average power control loop maintains a constant
average power level of the monitor current over
temperature and lifetime of the laser.
The average monitor current is programmable over a wide
current range from 150 to 1100 A by tuning the R
setting resistor.
The maximum allowable capacitive load on pin AVR and
pin BIASOUT is 100 pF.
The minimum capacitance on pin MON is 10 pF.
7.6
The TZA3010B can also operate in open-loop mode with
direct setting of the bias and modulation currents. The bias
and modulation current sources are transconductance
amplifiers and the output currents are determined by the
BIASIN and MODIN voltages respectively. The bias
current source has a bipolar output stage with minimum
output capacitance for optimum RF performance.
7.7
At power-up the bias and modulation current sources are
released once the V
and the reference voltage has reached the correct value of
1.2 V.
The control loop starts with minimum bias and modulation
current at power-up and when the device is enabled. The
current levels increase until the MON input current
matches the programmed average level.
2003 Apr 07
30 Mbits/s up to 3.2 Gbits/s
A-rate
Average loop control
Direct current setting
Soft start
laser driver
CCA
voltage exceeds the 2.7 V level
AVR
7
7.8
The TZA3010B features two alarm functions for the
detection of excessive laser operating current and monitor
diode current due to laser ageing, laser malfunctioning or
a too high laser temperature. The alarm threshold levels
are programmed by a resistor or a current source. For
DC-coupled application, the operating current equals the
bias current plus half of the modulation current.
7.9
A LOW level on the enable input disables the bias and
modulation current sources: the laser is off. A HIGH level
on the enable input or an open enable input switches both
current sources on: the laser is operational.
7.10
The reference voltage is derived from a band gap circuit
and is available at pin RREF. An accurate (1%) 10 k
resistor has to be connected to pin RREF to provide the
internal reference current. The maximum capacitive load
on pin RREF is 100 pF.
The reference voltage on the setting pins (MAXOP,
MAXMON, PWA and AVR) is buffered and derived from
the band gap voltage.
The output voltage on pin VTEMP reflects the junction
temperature of the TZA3010B, the temperature coefficient
of pin VTEMP equals 2.2 mV/K.
Alarm functions
Enable
Reference block
Product specification
TZA3010B