tza3011a NXP Semiconductors, tza3011a Datasheet - Page 10

• Manufacturer Part Number: tza3011a
• Description: 30 Mbit/s Up To 3.2 Gbit/s A-rate Tm Laser Drivers
• Manufacturer: NXP Semiconductors

Philips Semiconductors
9397 750 14437
Product data sheet
7.10 Enable
7.11 Reference block
7.6 Average loop control
7.7 Direct current setting
7.8 Soft start
7.9 Alarm functions
The maximum allowable capacitive load on pins AVR, ER, BIASOUT and MODOUT is
100 pF.
The average power control loop maintains a constant average power level of the monitor
current over temperature and lifetime of the laser. The average loop control is activated by
short-circuiting pin ER to ground.
The TZA3011 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.
At power-up the bias and modulation current sources are released when 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 and, in the case of dual-loop control, the extinction ratio.
The TZA3011 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. In the TZA3011A, for the AC-coupled application, the operating current is equal to
the bias current. In the TZA3011B, for the DC-coupled application, the operating current
equals the bias current plus half of the modulation current.
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.
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, ER and AVR) is
buffered and derived from the band gap voltage.
The output voltage on pin VTEMP reflects the junction temperature of the TZA3011, the
temperature coefficient of V
Rev. 06 — 20 January 2005
VTEMP
equals 2.2 mV/K.
30 Mbit/s up to 3.2 Gbit/s A-rate
TZA3011A; TZA3011B
© Koninklijke Philips Electronics N.V. 2005. All rights reserved.
CCA
laser drivers
> 2.7 V
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