PIP201-12M-3 Datasheet, PDF (12/20 Pages) NXP Semiconductors – DC-to-DC converter powertrain

Philips Semiconductors
PIP201-12M-3
DC-to-DC converter powertrain
printed-circuit board is approximately 5 K/W. In order to take full advantage of the low
thermal resistance of this package, the printed-circuit board must be designed so that
heat is conducted away efficiently from the package. This can be achieved by
maximizing the area of copper around each pad, and by incorporating thermal vias to
conduct the heat to inner and/or bottom layers of the printed-circuit board.
An example of a thermal via pattern is shown in Figure 13. In a typical application,
with no forced air cooling, the use of thermal vias typically reduces the thermal
resistance from 25 K/W to 20 K/W. The additional use of a small fan can reduce this
further to approximately 15 K/W.
PAD1
PAD2
PAD3
All holes 0.5 mm diameter with 1 mm spacing.
Fig 13. Printed-circuit board thermal via pattern.
03ag36
The thermal resistance of a particular design can be measured by passing a known
current through the source-drain diode of the lower MOSFET. The direction of current
flow is into V_SSO and out of V_O. The volt drop between V_SSO and V_O is then measured
and used to calculate the power dissipation in the PIP201-12M. The case
temperature of the PIP201-12M can be measured using an infra-red thermometer.
The thermal resistance can then be calculated using the following equation:
R_{th( j – pcb)} = ^T-----^c--^a-_I-^s---^e_×---^–--_V---^T-_F---^a--^m----^b(K ⁄ W )
(3)
where T_case is the measured case temperature (°C), T_amb is the ambient
temperature (°C), I is the MOSFET current (A), and V_F is the voltage drop between
V_SSO and V_DDO (V).
Where more than one phase is used, for example the circuit of Figure 11, the thermal
resistance of each PIP201-12M should be measured with current flowing in all
phases.
12. Test information
Figure 14 shows the test circuit used to measure power loss in the PIP201-12M. The
output voltage is measured using an averaging circuit. This eliminates losses in the
output inductor and the PCB tracks. The calculated power loss, using this method,
9397 750 11942
Product data
Rev. 03 — 19 November 2003
© Koninklijke Philips Electronics N.V. 2003. All rights reserved.
12 of 20