The LM5009A is a functional variant of the LM5009 COT buck switching regulator. The
functional differences of the LM5009A are: The minimum input operating voltage is 6 V, the ON-time
equation is slightly different, and the requirement for a minimum load current is removed.
The LM5009A step-down switching regulator features all of the functions required to
implement a low cost, efficient, buck bias regulator. This high voltage regulator contains an 100-V
N-channel buck switch. The device is easy to implement and is provided in the 8-pin VSSOP and the
thermally enhanced 8-pin WSON packages. The regulator is based on a control scheme using an ON time
inversely proportional to VIN. This feature allows the operating frequency
to remain relatively constant. The control scheme requires no loop compensation. An intelligent
current limit is implemented with forced OFF time, which is inversely proportional to
VOUT. This scheme ensures short-circuit control while providing minimum
foldback. Other features include: thermal shutdown, undervoltage lockout
(VCC), gate drive undervoltage lockout, max duty cycle limiter, and a
precharge switch.
