US 10,263,532 B2
Multiple power sources for a switching power converter controller
John L. Melanson, Austin, TX (US); and Eric J. King, Dripping Springs, TX (US)
Assigned to SIGNIFY HOLDING B.V., Eindhoven (NL)
Filed by John L. Melanson, Austin, TX (US); and Eric J. King, Dripping Springs, TX (US)
Filed on Mar. 31, 2011, as Appl. No. 13/77,421.
Claims priority of provisional application 61/369,202, filed on Jul. 30, 2010.
Prior Publication US 2012/0025608 A1, Feb. 2, 2012
Int. Cl. H02M 3/22 (2006.01); H02M 7/06 (2006.01); H02M 1/36 (2007.01); H05B 33/08 (2006.01); H02M 3/335 (2006.01); H02M 1/00 (2006.01)
CPC H02M 7/06 (2013.01) [H02M 1/36 (2013.01); H02M 3/22 (2013.01); H02M 3/33507 (2013.01); H05B 33/0815 (2013.01); H02M 2001/0006 (2013.01); Y02B 20/346 (2013.01); Y10T 307/352 (2015.04); Y10T 307/50 (2015.04)] 38 Claims
OG exemplary drawing
 
1. An apparatus comprising:
a first power supply having a first source follower transistor to conduct a start-up current for a controller and supply an operating voltage for the controller; and
a second power supply having a second source follower transistor to conduct a steady-state operational current for the controller and supply an operating voltage from a supply node for the controller, wherein a source of the first source follower transistor and a source of the second source follower transistor are coupled to the supply node and, during operation of the apparatus, when the source of the second source follower transistor is biased with the operating voltage at the supply node to cause the second source follower transistor to turn ON, the second source follower transistor changes the operating voltage and the change in the operating voltage at the supply node causes the first source follower transistor to automatically turn OFF.