EL6245C

Features:

• "Shrink-Small" Outline Package
• Voltage-controlled output current source, requiring one external set resistor per channel
• Auto oscillator on-off with OUTEN signals
• Rise time = 0.8ns
• Fall time = 0.8ns
• 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%)
• Disable feature for power-up protection and power savings
• Fast Settling APC Amplifier



Application

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



Pinout




Description

   The EL6245C is a high-performance three channel laser driver that provides controlled current to a grounded laser diode. Channels 2 and 3 should be used as the write channels, with switching speeds of approximately one nanosecond 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 IIN pin (virtually ground). The current seen at this pin is then amplified to become a current source at pin I_OUT.

   An on-chip 500MHz oscillator EL6245C is provided to allow output current modulation when in any mode. This is turned on only when the OSCEN and OUTEN pins are 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 EL6245C 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 IOUT shut-off is also achieved by holding the ENABLE pin low, which will override all other control pins.

   The EL6245C 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. Its 100MHz bandwidth and 30ns settling time enable up to 16X CD-RW design.