15

LTC1148

LTC1148-3.3/LTC1148-5

Board Layout Checklist

When laying out the printed circuit board, the following

checklist should be used to ensure proper operation of the

LTC1148 series. These items are also illustrated graphi-

cally in the layout diagram of Figure 9. Check the following

in your layout:

1. Are the signal and power grounds segregated? The

LTC1148 signal ground Pin 11 must return to the (–)

source of the N-channel MOSFET, anode of the

have as short lead lengths as possible.

able applications, the resistive divider R1, R2 must be

ground.

with minimum PC trace spacing? The 1000pF capacitor

between Pins 7 and 8 should be as close as possible to

the LTC1148.

P-channel MOSFET as closely as possible? This capaci-

tor provides the AC current to the P-channel MOSFET.

5. Is the 1

between Pin 3 and power ground Pin 12? This capacitor

carries the MOSFET driver peak currents.

6. Is the Shutdown Pin 10 actively pulled to ground during

normal operation? The Shutdown pin is high imped-

ance and must not be allowed to float.

Figure 9. LTC1148 Layout Diagram (See Board Layout Checklist)

APPLICATIO S I FOR ATIO

1

2

3

4

5

6

7

14

13

12

11

10

9

8

1

µF

D1

P-CHANNEL

1k

3300pF

10nF

LTC1148

R1

R2

N-CHANNEL

L

+

–

–

+

OUTPUT DIVIDER REQUIRED WITH

ADJUSTABLE VERSION ONLY

BOLD LINES INDICATE HIGH CURRENT PATHS

LTC1148 • F09

SHUTDOWN

1000pF

P-DRIVE

N-DRIVE

PGND

SGND

SHDN

NC

NC