4
DEMO MANUAL DC252
DESIGN-READY SWITCHER
This demonstration board is easy to set up to evaluate
the performance of the LTC1736. Please follow the
procedure outlined below for proper operation. Sol-
dered wire connections are required to properly evalu-
ate the performance of this switching regulator.
• Refer to Figure 2 for proper connection of monitoring
and measurement equipment.
• Connect the input power supply to the V
IN
and GND
terminals on the right-hand side of the board with
soldered connections. Do not increase V
IN
over 28V
or the MOSFET(s) WILL BE DAMAGED.
• Connect the load between the V
OUT
and GND termi-
nals on the right side of the board with soldered
connections.
• The RUN pin can be left unconnected. To shut down
the LTC1736, tie this pin to ground.
• Set jumper JP4 for the desired output voltage. (See
Table 1.)
• If an external 5V supply is used, connect it to EXTV
CC
.
• Set the jumper JP1 so that FCB selects the desired
mode:
JP1
MODE
On
Burst Mode Operation, Connect PGood to FCB/Sync
Off
Forced Continuous
Open
Apply External Clock to FCB/Sync
• Jumper JP2 determines if the overcurrent latchoff is
enabled. With JP2 installed this function is disabled.
Remove JP2 to enable.
JP2
OVERCURRENT LATCHOFF
Installed
Disabled
Removed
Enabled
• Active loads can cause confusing results. Refer to the
active load discussion in the Operation section.
QUICK START GUIDE
I TRODUCTIO
U
U
The circuit in Figure 1 highlights the capabilities of the
LTC1736.
The LTC1736 is a synchronous step-down switching
regulator controller that drives external N-channel power
MOSFETs using a fixed frequency architecture with OPTI-
LOOP compensation. OPTI-LOOP compensation effectively
removes the constraints placed on C
OUT
by other controllers
for proper operation (such as restrictions on very low
ESRs). Burst Mode operation provides high efficiency at
low load currents. Operating efficiencies typically exceed
80% over more than two decades of load current range.
Do not use spring clip leads when testing this circuit.
Soldered wire connections are required to properly test
the performance of the PC board.
This demonstration circuit is intended for the evaluation of
the LTC1736 switching regulator IC and was not designed
for any other purpose.
LTC1736CG
DEMO CIRCUIT DC252A
(408) 432-1900
VID CPU POWER CONVERTER
JP2 LATCHOFF
JP3
PGOOD
V
O
PROG
JP4
B4
B0
JP1 BURST
EXT CLOCK
(REMOVE JP1 IF USED)
FCB/SYNC
EXTV
CC
PGOOD
OFF
ON
GND
GND
GND
V
OSNS
+V
OUT
+V
IN
I
IN
RUN
–
+
LOAD
V
OUT
I
OUT
+
–
+
–
OPTIONAL REMOTE
V
OUT
SENSE CONNECTION
OPTIONAL EXTERNAL
HIGH FREQUENCY
SOURCE CONNECTION
A
A
252 F02
V
IN
Figure 2
