Linear Technology DC257, Демонстрационное руководство, Страница: 8 / 13

8
DEMO MANUAL DC257
NO-DESIGN SWITCHER
Figure 5. Proper Measurement Setup
MONOLITHIC SYNCHRONOUS
STEP-DOWN REGULATOR
LTC1707CS8
V
REF
V
OUT
V
IN
V
OUT
V
OSENSE
RUN/SS
GND
GND
E1 E8
E2
E3
E4
E5
E7
E6
SYNC/
MODE
+
V
IN
+
A
+
V
+
V
I
IN
+
A
I
OUT
1.8V 2.5V 1.5V 2.9V 3.3V OPEN
JP1
LOAD
DEMO CIRCUIT
DC257
Linear Technology
(408) 432-1900
DC257 F05
10
Ω
Figure 6. Remote Output Voltage Sense
MONOLITHIC SYNCHRONOUS
STEP-DOWN REGULATOR
LTC1707CS8
V
REF
V
OUT
V
IN
V
OUT
V
OSENSE
RUN/SS
GND
GND
E1 E8
E2
E3
E4
E5
E7
E6
SYNC/
MODE
CUT THIS
TRACE
+
V
IN
+
A
+
V
+
V
I
IN
+
A
I
OUT
1.8V 2.5V 1.5V 2.9V 3.3V OPEN
JP1
LOAD
DEMO CIRCUIT
DC257
Linear Technology
(408) 432-1900
DC257 F06
10
Ω
OPERATIO
U
This applies to line regulation (input-to-output voltage
regulation) as well as load regulation tests. In doing the
line regulation tests, always look at the input voltage
across the input terminals.
For the purposes of these tests, the demonstration circuit
should be powered from a regulated DC bench supply, so
that variations on the DC input do not add errors to the
regulation measurements.
REMOTE OUTPUT-VOLTAGE SENSING
Remote output-voltage sensing can be accomplished by
modifying the PC board. A small PC trace connecting V
OUT
to V
OSENSE
must be cut, as shown in Figure 6. An external
connection from V
OSENSE
directly to the load must be
made. To prevent uncertainty, there is a 10
Ω
resistor
placed across the V
OUT
and V
OSENSE
terminals. Never,
under any circumstance, allow V
OSENSE
to float!