EL6273C

Features:

• "Shrink-Small" Outline Package
• Voltage-controlled output current source to 140mA per channel, requiring one external set resistor per channel
• Current-controlled output current source to 140mA per channel
• Rise time = 3.0ns
• Fall time = 3.5ns
• On chip oscillator with frequency and amplitude control by use of external resistors to ground
• Oscillator to 500MHz
• Oscillator to 100mA pk/pk
• Single +5V supply (±10%)
• Current amplification = 400X
• Disable feature for power-up protection and power savings
• TTL/CMOS control signals
• Fast Settling APC Amplifier



Application

• CD-RW applications
• Writable optical drives
• Laser diode current switching




Pinout




Description

   The EL6273C is a high-performance three channel laser driver that provides controlled current to a grounded laser diode. Three amplifiers can provide up to 140mA per channel of DC or pulsed current. Channels 2 and 3 should be used as the write channels, with switching speeds of approximately three nanoseconds rise/fall time. All three channels are summed together at the I_OUT output, allowing the user to create multilevel waveforms in order to optimize laser diode performance. The level of the output current is set by an analog voltage applied to an external resistor which converts the voltage into a current at the I_IN pin (virtually ground). The current seen at this pin is then amplified by 400X to become a current source at pin I_OUT.

   An on-chip 500MHz oscillator EL6273C is provided to allow output current modulation when in any mode. This is turned on when the OSCEN pin is held high. Complete control of amplitude and frequency is set by two external resistors connected to ground at pins RFREQ and RAMP (see graphs in this data sheet for further explanation).

   Output current pulses EL6273C are enabled when an 'L' signal is applied to the OUTEN pin. No output current flows when OUTEN is 'H', and additional laser diode protection is provided since the OUTEN input will float high when open. Complete I_OUT shut-off is also achieved by holding the ENABLE pin low, which will override all other control
pins.

The EL6273C also includes a fast settling APC amplifier designed to
interface directly with the front end monitor diode and the sampleand-
hold amplifier for read and write power control. It's 40MHz bandwidth
and 150 ns settling time enable up to 8X CD-RW design.