ZHCSIX0H March 2009 – October 2018 LM5008A
PRODUCTION DATA.
The on-time for the LM5008A is determined by the RT resistor and is inversely proportional to the input voltage (VIN), resulting in a nearly constant frequency as Vin is varied over its range. The on-time equation for the LM5008A is Equation 4.
RT must be selected for a minimum on-time (at maximum VIN) greater than 400 ns, for proper current limit operation. This requirement limits the maximum frequency for each application, depending on VIN and VOUT.
The LM5008A can be remotely disabled by taking the RT/SD pin to ground. See Figure 9. The voltage at the RT/SD pin is between 1.5 V and 3 V, depending on VIN and the value of the RT resistor.