Tripath Technology, Inc. - Technical Information
DD
Drain diode. This diode must be connected from the drain of the high side output
MOSFET to the drain of the low side output MOSFET. This diode absorbs any high
frequency overshoots caused by the output inductor LO during high output current
conditions. In order for this diode to be effective it must be connected directly to the
drains of both the top and bottom side output MOSFET. A fast or ultra fast recovery
diode that can sustain the entire VPP-VNN voltage should be used here. In most
applications a 150V or greater diode must be used.
DS
Source diode. This diode must be connected from the source of the high side
output MOSFET to the source of the low side output MOSFET. This diode absorbs
any high frequency undershoots caused by the output inductor LO during high output
current conditions. In order for this diode to be effective it must be connected
directly to the sources of both the top and bottom sides output MOSFETs. A fast or
ultra fast recovery diode that can sustain the entire VPP-VNN voltage should be
used here. In most applications a 150V or greater diode must be used.
Gate resistor for the output MOSFET for the switchmode power supply. Controls
the rise time, fall time, and reduces ringing for the gate of the output MOSFET for
the switchmode power supply.
RPG
QB
Output MOSFET for the switchmode power supply to generate the VN10. This
output MOSFET must be a P channel device.
DSW
Flywheel diode for the internal VN10 buck converter. This diode also prevents
VN10SW from going more than one diode drop negative with respect to VNN. This
diode should be a Shottky or ultrafast rectifier.
LSW
VN10 generator filter inductor. This inductor should be sized appropriately so that
LSW does not saturate, and VN10 does not overshoot with respect to VNN during
TK2150 turn on.
CSW
VN10 generator filter capacitors. The high frequency capacitor (0.1uF) must be
located close to the VN10 pins (pin 41 and 43 of the TP2150) to maximize device
performance. The bulk capacitor (100uF) should be sized appropriately such that
the VN10 voltage does not overshoot with respect to VNN during TK2150 turn on.
VN10 generator feedback resistor. This resistor sets the nominal VN10 voltage.
With RSWFB equal to 1kΩ, the VN10 voltage generated will typically be 10V above
VNN.
RSWFB
CSWFB
VN10 generator feedback capacitor. This capacitor, in conjunction with RSWFB, filters
the VN10 feedback signal such that the loop is unconditionally stable.
12
TK2150 – Rev. 1.0/12.02
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