Техническая Спецификация для Infineon Technologies Step-Down DC/DC Controller TLE 6390 DEMOBOARD TLE 6389-2GV DEMOBOARD TLE 6389-2GV

Datasheet Rev. 2.1

25

2007-08-13

In the following, some internal blocks of the TLE6389 are described in more detail. For 
the right choice of the external components please refer to the section application 
information.

To meet the strict requirements in terms of current consumption demanded by all Body-
and 42V PowerNet applications a special PFM (Pulse Frequency Modulation) - PWM 
(Pulse Width Modulation) control scheme for highest efficiency is implemented in the 
TLE 6389 regulators. Under light load conditions the output voltage is able to increase 
slightly and at a certain threshold the controller jumps into PFM mode. In this PFM 
operation the PMOS is triggered with a certain on time (depending on input voltage, 
output voltage, inductance- and sense resistor  value) whenever the buck output voltage 
decreases to the so called WAKE-threshold.  The switching frequency of the step down 
regulator is determined in the PFM mode by the load current. It increases with increasing 
load current and turns finally to the fixed PWM frequency at a certain load current 
depending on the input voltage, current sense resistor and inductance. The diagram 
below shows the buck regulation circuit of the TLE 6389 .

The TLE 6389 uses a slope-compensated peak current mode PWM control scheme in 
which the feedback or output voltage of the step down circuit and the peak current of the 
current through the PMOS are compared to form the OFF signal for the external PMOS.