User`s guide

System Operation

FIGURE 4-3: ISOLATION BOUNDARY ON SMPS AC/DC REFERENCE

DESIGN

Table 4-2 lists the location where each functional block resides with respect to the

isolation barrier.

TABLE 4-2: LOCATION OF FUNCTIONAL BLOCK WITH RESPECT TO

ISOLATION BARRIER

Isolation Boundary

+12V

GND

+3.3V

GND

+5V

GND

NOTICE

During testing and evaluation of the SMPS AC/DC Reference Design, no equipment

should be connected across the isolation boundary. This applies to oscilloscope

probes, multimeters, and programmers/debuggers. Under no circumstances should the

Live_GND (on the primary or “live” side) and GND (on the secondary or “isolated” side)

be tied together.

As a general rule, the primary (live) side and the secondary (isolated) side should

always be tested independently with no connections across the isolation boundary.

Before connecting oscilloscope probes to the SMPS AC/DC Reference Design, ensure

that the oscilloscope is isolated from the SMPS AC/DC Reference Design.

Functional Block

Live or Isolated Side?

Power Circuit Control Circuit

EMI Filter Primary (Live) N/A

Bridge Rectifier Primary (Live) N/A

PFC Boost Converter Primary (Live) Primary (Live)

Full-Bridge Converter Primary (Live) Primary (Live)

Synchronous Rectifier Secondary (Isolated) Primary (Live)

Multi-Phase Buck Converter Secondary (Isolated) Secondary (Isolated)

Single-Phase Buck Converter Secondary (Isolated) Secondary (Isolated)