tza3050 NXP Semiconductors, tza3050 Datasheet - Page 7

• Manufacturer Part Number: tza3050
• Description: Tza3050 30 Mbits/s Up To 1.25 Gbits/s Burst Mode Laser Driver
• Manufacturer: NXP Semiconductors

Philips Semiconductors
9397 750 14806
Product data sheet
7.10 Enable
7.11 Reference block
7.8 Burst mode
7.9 Alarm functions
The TZA3050 is compliant with burst mode application. Fast switch on and off of bias and
modulation currents is allowed in less than 100 ns via pin ENABLE.
When internal average loop control is used, the average power settings can be maintained
between two bursts of data via an external capacitor on pin CBIAS.
During a burst, this capacitor defines the time constant of the loop. Between bursts, the
capacitor is automatically disconnected from the internal circuitry and is used as a
memory cell.
A more complex memory cell can also be connected to pin CBIAS.
The TZA3050 features two alarm functions for the detection of excessive laser operating
current and monitor diode current due to laser ageing, laser malfunctioning or a high laser
temperature. The alarm threshold levels are programmed by a resistor or a current
source. 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 allowable 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 TZA3050. The
temperature coefficient of V
Rev. 03 — 7 April 2005
VTEMP
30 Mbits/s up to 1.25 Gbits/s burst mode laser driver
equals 2.2 mV/K.
© Koninklijke Philips Electronics N.V. 2005. All rights reserved.
TZA3050
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