We are using the LNK 306 as we require up to 200mA current to drive leds and a voltage regulator ic to drop the 12volts down to 5v to provide a small current to recharge a battery, nominal current we require is around 150mA . we are using the circuit given on page 4 of the 302-304-306.pdf however as soon as the current reaches 120mA we get a pulsating effect with the leds pulsating at a frequency of around 1 hz. The leds are 3 in series with a 75 ohm resistor and this is in parallel with 2 leds in series with a 300 ohm resistor. if we apply a 12 dc power supply to the circuit -at the output of the lnl306 - it shows we are taking 150mA which is correct. Our R&D team have spent much time looking for a solution but have not been able to determine the cause.