DEMO MANUAL DC1905A
LTM4633
High Efficiency, Triple 10A
Step-Down µModule Regulator
Description
Demonstration circuit DC1905A features the
LTM
®
4633EY,
a high efficiency, triple 10A step-down power µModule
®
regulator. The input voltage range is from 4.7V to 16V with
common input source, or 2.375V to 16V with an external bias
supply. The output voltage range is 0.8V to 1.8V for Channel 1
and Channel 2, 0.8V to 5.5V for Channel 3. Derating is
necessary for certain V
IN
, V
OUT
, frequency and thermal con-
ditions. The DC1905A offers access to the TRACK/SS pins
allowing the user to program output tracking or soft-start
period. The board operates in continuous conduction mode
in heavy load conditions. For high efficiency at low load
currents, the MODE jumper (JP4) selects pulse-skipping
mode for noise sensitive applications or Burst-Mode
®
operation in less noise sensitive applications. Channel 1
and 2 can be connected in parallel for a single 20A output
solution with optional jumper resistors. The LTM4633 data
sheet must be read in conjunction with this demo manual
prior to working on or modifying demo circuit DC1905A.
Design files for this circuit board are available at
http://www.linear.com/demo/DC1905A
L,
LT, LTC, LTM, Burst Mode, µModule, Linear Technology and the Linear logo are registered
trademarks of Linear Technology Corporation. All other trademarks are the property of their
respective owners.
BoarD photo
dc1905af
1
DEMO MANUAL DC1905A
performance summary
PARAMETER
Input Voltage Range
Output Voltages
Maximum Continuous Output Current
Operating Frequency
Efficiency of Channel 1
Efficiency of Channel 2
Efficiency of Channel 3
Load Transient of Channel 1
Load Transient of Channel 2
Load Transient of Channel 3
V
IN
= 12V, V
OUT1
= 1.0V, I
OUT1
= 10A
V
IN
= 12V, V
OUT2
= 1.2V, I
OUT2
= 10A
V
IN
= 12V, V
OUT3
= 3.3V, I
OUT3
= 10A
V
IN
= 12V, V
OUT1
= 1.0V, I
STEP
= 0A to 5A
V
IN
= 12V, V
OUT2
= 1.2V, I
STEP
= 0A to 5A
V
IN
= 12V, V
OUT3
= 3.3V, I
STEP
= 0A to 5A
Derating Is Necessary for Certain Operating Conditions.
See Data Sheet for Details
Specifications are at T
A
= 25°C
VALUE
4.7V to 16V
1.0V, 1.2V, 3.3V ±1.5%
10ADC for Each Channel
750kHz
77% See Figure 2
81% See Figure 3
91% See Figure 4
See Figure 5
See Figure 6
See Figure 7
CONDITIONS
Quick start proceDure
Demonstration circuit DC1905A is an easy way to evalu-
ate the performance of the LTM4633EY. Please refer to
Figure 1 for proper measurement equipment setup and
follow the procedure below:
1. Place jumpers in the following positions for a typical
application:
RUN1
ON
RUN2
ON
RUN3
ON
MODE
CCM
5. (Optional) For optional load transient test, apply an
adjustable pulse signal between IOSTEP_CLK and GND
test points. The pulse amplitude sets the load step cur-
rent amplitude. Keep the pulse width short (<1ms) and
pulse duty cycle low (<5%) to limit the thermal stress
on the load transient circuit. Switch the jumper resistors
R30, R31 or R34 (on the backside of boards) to apply
load transient on channel 1, channel 2, or channel 3
respectively.
6. (Optional) LTM4633 can be synchronized to an external
clock signal. Place the JP4 jumper on EXT_CLK and
apply a clock signal (0V to 5V, square wave) on the
CLKIN test point.
7. (Optional) The outputs of LTM4633 can track another
supply. If tracking external voltage is selected, the cor-
responding test points, TRACK1, TRACK2, and TRACK3,
need to be connected to a valid voltage signal.
8. (Optional) Channel 1 and 2 can be connected in paral-
lel for a 20A polyphase operation on DC1905A. Install
0Ω resistors on R32, R33, R35, R36 and remove R15.
Output voltage is set by R4 based on equation V
OUT
=
0.8V (1 + 60.4k/2/R4).
2. With power off, connect the input power supply, loads
and meters as shown in Figure 1. Preset the load to 0A
and V
IN
supply to 12V.
3. Turn on the power supply at the input. The output
voltage of channel 1 should be 1.0V ±1.5% (0.985V
to 1.015V). The output voltage of channel 2 should be
1.2V ±1.5% (1.182V to 1.218V). The output voltage of
channel 3 should be 3.3V ±1.5% (3.25V to 3.349V).
4. Vary the input voltage from 4.7V to 16V and adjust the
load current of each channel from 0A to 10A. Observe
the output voltage regulation, ripple voltage, efficiency,
and other parameters.
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DEMO MANUAL DC1905A
Quick start proceDure
DC1905A Efficiency (LTM4633) V
OUT
= 1.0V
100
90
80
70
EFFICIENCY (%)
60
50
40
30
20
10
0
0
2
4
6
LOAD CURRENT (A)
V
IN
= 5V
V
IN
= 8V
V
IN
= 12V
V
IN
= 16V
8
10
dc1905a F02
DC1905A Efficiency (LTM4633) V
OUT
= 1.2V
100
90
80
70
EFFICIENCY (%)
60
50
40
30
20
10
0
0
2
4
6
LOAD CURRENT (A)
V
IN
= 5V
V
IN
= 8V
V
IN
= 12V
V
IN
= 16V
8
10
dc1905a F03
Figure 2. Measured Efficiency on Channel 1. V
OUT1
= 1.0V,
f
SW
= 750kHz, CCM, Channel 2, 3 Disabled
Figure 3. Measured Efficiency on Channel 2. V
OUT2
= 1.2V,
f
SW
= 750kHz, CCM, Channel 1, 3 Disabled
DC1905A Efficiency (LTM4633) V
OUT
=3.3V
100
90
80
70
EFFICIENCY (%)
60
50
40
30
20
10
0
0
2
4
6
LOAD CURRENT (A)
V
IN
= 5V
V
IN
= 8V
V
IN
= 12V
V
IN
= 16V
8
10
dc1905a F04
Figure 4. Measured Efficiency on Channel 3. V
OUT3
= 3.3V,
f
SW
= 750kHz, CCM, Channel 1, 2 Disabled
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