6

4325.1

November 3, 2005

The over-current function will trip at a peak inductor current

- typical). The OC trip point varies mainly due to the

from the equation above with:

3. Determine

,

where

∆I is the output inductor ripple current.

For an equation for the ripple current see the section under

component guidelines titled ‘Output Inductor Selection’.

A small ceramic capacitor should be placed in parallel with

presence of switching noise on the input voltage.

Application Guidelines

Layout Considerations

As in any high frequency switching converter, layout is very

important. Switching current from one power device to another

can generate voltage transients across the impedances of the

interconnecting bond wires and circuit traces. These

interconnecting impedances should be minimized by using

wide, short printed circuit traces. The critical components

should be located as close together as possible using ground

plane construction or single point grounding.

Figure 5 shows the critical power components of the

converter. To minimize the voltage overshoot the

interconnecting wires indicated by heavy lines should be part

of ground or power plane in a printed circuit board. The

components shown in Figure 6 should be located as close

Locate the HIP6013 within 3 inches of the MOSFETs, Q1.

The circuit traces for the MOSFETs’ gate and source

connections from the HIP6013 must be sized to handle up to

1A peak current.

Figure 6 shows the circuit traces that require additional

layout consideration. Use single point and ground plane

construction for the circuits shown. Minimize any leakage

close to the SS pin because the internal current source is

only 10

µA. Provide local V

to the BOOT and PHASE pins.

0A

0V

TIME (20ms/DIV)

5A

10A

15A

2V

4V

FIGURE 4. OVER-CURRENT OPERATION

I

PEAK

I

OCSET

R

OCSET

•

r

DS ON

()

---------------------------------------------------

=

()

∆I

() 2

⁄

+

>

FIGURE 5. PRINTED CIRCUIT BOARD

POWER AND GROUND PLANES OR ISLANDS

UGATE

PHASE

Q1

D2

RETURN

HIP6013

+12V

HIP6013

SS

GND

BOOT

D1

Q1

D2

PHASE

FIGURE 6. PRINTED CIRCUIT BOARD

SMALL SIGNAL LAYOUT GUIDELINES

HIP6013