MV1001SC

18

4. Cautions on pattern designing

4.1 Cautions

Figure 12 shows the same circuit shown in Figure 4, rewritten after accounting for pattern design. Consider the four

items below for pattern design. Due to the potential for false detection, pay special attention to items 1 and 2.

1.

The shaded area indicates the main circuit through which the switching current flows. To make this area as small as

possible, wire with the shortest possible tracks, prioritizing this aspect over other aspects.

2.

The area enclosed with a dotted line indicates the control circuit. Strive to minimize the effects of noise and magnetic

flux of the main circuit on the control circuit. The control circuit should have one GND pin, connected to a stable part

of the main circuit, such as a minus terminal of the input capacitor. In particular, make sure that the tracks to input

signals to pins such as REF, Svin, Svout, and CS pins are kept at a distance from high-voltage circuits.

3.

Magnetic flux is present around the inductor. Use a shield type inductor with a small flux leak. Make sure that the

signal tracks are not placed just below the inductor.

4.

Wire the tracks for the Svin and Svout pins as close to parallel as possible.

Figure 12 Circuit diagram accounting for pattern design

C1

C2

R1

R4

R9

D2

D1

Q1

R6

R5

R7

C5

C3

C4

C9

L1

Vin

GND

LED+

LED-

LED

R8

C8

R2

4

MV1001SC

3

2

1

5

6

7

8

REF

R3

Cr

CAT.No.1A0102-1E