Single Output/Dual Phase Operation - Linear Technology DC1822A Demo Manual

DEMO MANUAL DC1822A
Quick start proceDure

SINGLE OUTPUT/DUAL PHASE OPERATION

A single output/dual phase converter may be preferred
for higher output current applications. The optional com-
ponents required to tie the phases together are found on
the bottom of the schematic shown in Figure 8. To tie the
two outputs together, make the following modifications:
1. Stuff 0Ω at R36 and R47 to tie the two outputs together.
2. Select one rail to be the master.
• If VOUT1 is the master, then stuff 0Ω at R51 to disable
the error amplifier for phase 2. Also stuff 0Ω at R52.
• If VOUT2 is the master, then stuff 0Ω at R49 to disable
the error amplifier for phase 1. Also stuff 0Ω at R50.
3. Remove the 0Ω jumper at R13 and stuff a 100pF
capacitor at C14 for the IAVG signal.
4
1.5VO(AC)
50mV/DIV
25A
12.5A
LOAD STEP
5A/DIV
Figure 4. Load Step Response of the DC1822A 1.5V Rail at V
C = 3× Sanyo 2R5TPE330M9 || 2× 100µF X5R 6.3V 1210, L = 0.47µH,
OUT
f = 500kHz
SW
1.2VO(AC)
50mV/DIV
25A
12.5A
LOAD STEP
5A/DIV
Figure 5. Load Step Response of the DC1822A 1.2V Rail at V
C = 3× Sanyo 2R5TPE330M9 || 2× 100µF X5R 6.3V 1210, L = 0.47µH,
OUT
f = 500kHz
SW
88mV
20µs/DIV
dc1822a F04
IN
91mV
20µs/DIV
dc1822a F05
IN
4. Stuff 0Ω at R53, R48 and R54 to tie the COMP , TRK/SS
and RUN pins together.
5. Remove the redundant compensation components.
PARALLELING BOARDS
The DC1822A demo boards can be tied together to form a
converter with up to 12 phases. To tie the boards together,
place the boards side-by-side and then connect the boards
by connecting J8 of one board to J9 of the other. This
will connect the IAVG, COMP , TRK/SS and signal ground
signals together. Next, use copper strips to tie the VOUT
planes, the VIN planes and GND planes of the two adjacent
boards together. The board has exposed copper along the
edges of the board for this purpose. Figure 6 shows how
to set up a 4-phase converter and Figure 7 shows how to
set up a 3-phase plus single phase converter.
= 12V.
= 12V.
dc1822af