TPS51640A, TPS59640, TPS59641
SLUSAQ2 –JANUARY 2012
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RCS eff ´ ACS
( )
0.66mW ´12
RGDROOP
=
=
= 4.12kW
RLL ´ GM
3.9mW ´0.497mS
(15)
Step Nine: Programming the CTHERM and GTHERM pins.
The CTHERM and GTHERM pins should be set so that the resistor divider voltage would be greater than 458
mV at normal operation. For VR_HOT to be asserted, the xTHERM pin voltage should fall below 458 mV. The
NTC resistor from xTHERM to GND is chosen as 100 kΩ with a B of 4250K. With this, for a VR_HOT assertion
temperature of 105°C, the resistor from xTHERM to VREF can be calculated as 15.4 kΩ.
Step Ten: Determine the output capacitor configuration.
For the output capacitor, the Intel Power Delivery guideline gives the output capacitor recommendations. Using
these devices, it is possible to meet the load transient with lower capacitance by using the OSR and USR
feature. Eight settings are available and this selection has to be tuned based on transient measurement.
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