LED Driver with Programmable Prebias Voltage

The MAX3966 is a programmable LED driver for fiber optic transmitters operating at data rates up to 266Mbps. The circuit contains a high-speed current driver with programmable temperature coefficient (tempco), adjustments for LED prebias voltage, and a VBB reference voltage generator. The circuit accepts PECL data inputs, and operates from a single +3V to +5.5V power supply.

The MAX3966 can switch up to 100mA into typical high-speed light-emitting diodes. As temperature increases, the device's modulation current increases with a tempco that is programmable from 2500ppm/°C to 12,000ppm/°C. The modulation current is programmed with a single external resistor.

The MAX3966's LED prebias voltage is programmable from 400mV to 925mV. The prebias circuit produces peaking current, which improves the LED switching speed.

Complementary current outputs help to maintain a constant supply current, reducing EMI and supply noise generated by the transmitter module. The MAX3966 is available in die form, or in 16-pin and 24-pin QSOP packages.

Applications

* 155Mbps ATM * 266Mbps Fibre Channel * ESCON * Fast Ethernet * FDDI * Multimode LED Transmitters

* Programmable LED Prebias Voltage

* Single +3V to +5.5V Power Supply

* Complementary Output Reduces Supply Noise

* Adjustable Modulation Current

* Adjustable Temperature Compensation

* Available in 16-Pin/24-Pin QSOP or Die