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dc2002af
DEMO MANUAL DC2002A
Quick start proceDure
Demonstration circuit 2002A is easy to set up to evaluate
the performance of the LTC3774EUHE. Please refer to
Figure 1 for proper measurement equipment setup and
follow the procedure below.
1. With power off, connect the input supply, load and
meters as shown in Figure 1. Preset the load to 0A
and V
IN
supply to be 0V. For both assemblies, place
the jumpers in the following positions:
JP1
RUN1
ON
JP2
RUN2
ON
JP5
MODE
CCM
2. Adjust the input voltage to be between 7V and 14V.
V
OUT1
should be 1.5V ±2%.
V
OUT2
should be 1.2V ±2%.
3. Next, apply 30A load to each output and re-measure
V
OUT
.
4. Once the DC regulation is confirmed, observe the output
voltage ripple, load step response, efficiency and other
parameters.
Note 1. Use the BNC connectors labeled V
OUT1
or V
OUT2
to measure the output voltage ripple.
Note 2. Do not connect load from the V
OS1
+
turret to the
V
OS1
–
turret or from the V
OS2
+
turret to the V
OS2
–
tur-
ret. This could damage the converter. Only apply load
across the stud connectors on the edge of the board.
Dynamic Load Circuit (Optional)
Demonstration circuit 2002A provides a simple load step
circuit consisting of a MOSFET and sense resistor for each
rail. To apply a load step, follow the steps below.
1. Pre-set the amplitude of a pulse generator to 0.0V and
the duty cycle to 5% or less.
2. Connect the scope to the V
OUT1
/V
OUT2
BNC connectors
for the rail under test with a coax cable. To monitor the
load step current, connect the scope probe across the
ISTEP± turrets for that rail.
3. Connect the output of the pulse generator to the PULSE
GEN turret for the rail under test and connect the return
to the adjacent GND turret.
4. With the converter running, slowly increase the am-
plitude of the pulse generator output to provide the
desired load step pulse height. The scaling for the load
step signal is 5mV/Amp.
Single Output/Dual Phase Operation
A single output/dual phase converter may be preferred for
higher output current applications. The optional compo-
nents required to tie the phases together are found on the
lower left of the 1st sheet. To tie the two outputs together,
make the following modifications:
1. Tie the two V
OUT
shapes together with a piece of copper
or a 0mΩ jumper at R47 and R36. One part to consider
is Tepro RN5326.
2. Tie V
OSNS1
to V
OSNS2
by stuffing a 0Ω resistor at R53
and tie V
OS1
–
to V
OS2
–
by stuffing a 0Ω resistor at R92.
3. Tie ITH1 to ITH2 by stuffing a 0Ω resistor at R68.
4. Tie RUN1 to RUN2 by stuffing a 0Ω resistor at R54.
5. Tie TK/SS1 to TK/SS2 by stuffing a 0Ω resistor at R48.
Paralleling Boards
Up to 6 DC2002A demo boards can be paralleled to
produce a single output, 12 phase converter. To connect
two or more DC2002A boards together, first tie the two
phases together as described in the Single Output/Dual
Phase Operation section. Next, place the boards side by
side such that header J8 of one board mates with socket
J9 of the other. This will connect the common control
signals together which are the V
OSNS
, V
OS
–
, ITH, RUN
and TK/SS signals. It will also tie the CLKOUT signal of
one phase to the PLLIN input of the other phase. Next,
tie the V
OUT
, V
IN
and GND of the boards together using
the exposed copper on the edges of the board. Figure 6
shows how to tie 2 boards together for a single output,
4 phase converter.
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