DEMO MANUAL DC1477B
LTM4609EV: 36V
IN
, 34V
OUT
Buck-Boost DC/DC
µModule
®
Regulator
Description
Demonstration circuit DC1477B features the
LTM
®
4609EV,
the high voltage, high efficiency, high density switch mode
buck-boost power module. The LTM4609EV regulates
an output voltage above, below, or equal to the input
voltage. DC1477B accepts an input voltage from 10V
to 36V with a preset output voltage of 30V at up to 3A.
Derating may be necessary for certain V
IN
, V
OUT
, and
thermal conditions. An optional input π filter is added on
the DC1477B to minimize the input ripple. The switching
frequency may be synchronized to an external clock from
200kHz to 400kHz to reduce undesirable frequency har-
monics and/or parallel multiple modules for even higher
output current. The LTM4609 data sheet must be read in
conjunction with this demo manual prior to working on
or modifying demo circuit DC1477B.
Design files for this circuit board are available at
http://www.linear.com/demo/DC1477B
L,
LT, LTC, LTM, µModule, Linear Technology and the Linear logo are registered trademarks of
Linear Technology Corporation. All other trademarks are the property of their respective owners.
performance summary
PARAMETER
Minimum Input Voltage
Output Voltage V
OUT
Maximum Continuous Output Current
CONDITIONS
(T
A
= 25°C)
VALUE
10V to 36V
30V ± 2%
Derating is Necessary for Certain V
IN
, V
OUT
, and Thermal
Conditions
3ADC at 10V
IN
8ADC at 24V
IN
10ADC at V
IN
> 30V
300kHz
96.7%, See Figure 3 for More Information
Default Operating Frequency
Efficiency
V
IN
= 20V, V
OUT
= 30V, I
OUT
= 3A
BoarD photo
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1
DEMO MANUAL DC1477B
Quick start proceDure
Demonstration circuit DC1477B is an easy way to evalu-
ate the performance of the LTM4609EV. 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
30V
OUT
application:
RUN
ON
CLOCK
PROG
MODE
CCM
START
SSO
5. To measure input and output ripple, please refer to
Figure 2 for proper setup.
6. To adjust the switching frequency turn off the power
supply and modify R6 and R7. Do not allow voltage at
pin PLLFLTR to exceed 2.4V.
7. Inductor and R
SENSE
should be modified to accom-
modate certain input and output condition. Refer to
the data sheet for details.
8. The input filter formed by CIN2, L2 and L3, CIN3 and
CIN4 is for the purpose of reducing the input voltage
ripple. The magnetic beads L2 and L3 are not necessary,
but they help to reduce the high frequency ringings on
the input supply significantly. See Figure 5 for details.
9. The optional components Rsnb1 and Csnb1, Rsnb2 and
Csnb2 can be used to form RC snubber circuits on the
switching nodes, which may help to reduce the output
ripple. Refer to the data sheet for details.
2. With the power supply off, connect the input power
supply, load and meters as shown in Figure 1. Preset
the load to 0A and V
IN
supply between 10V to 36V.
3. Turn on the power at the input. The output voltage
should be 30V ± 2%.
4. Once the proper output voltage is established, adjust the
load within the operating range and observe the output
voltage regulation, ripple voltage, efficiency and other
parameters. A cooling fan and heat sink are necessary
for V
IN
<10V and I
OUT
= 3A.
2
dc1477bfa
DEMO MANUAL DC1477B
Quick start proceDure
–
+
LOAD
0 TO 3A
–
+
–
V
IN
–
+
+
+
–
Figure 1. Test Setup of DC1477B
INPUT OR OUTPUT CAPACITOR
Figure 2. Proper Scope Probe Placement for Measuring Input or Output Ripple
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DEMO MANUAL DC1477B
Quick start proceDure
DC1477B/LTM4609 EFFICIENCY AT 10V
IN
Input
100
90
EFFICIENCY (%)
80
70
60
50
0
0.5
1
1.5
2
LOAD CURRENT (A)
2.5
CCM
BURST
DCM
DC1477B/LTM4609 EFFICIENCY AT 20V
IN
Input
100
90
EFFICIENCY (%)
80
70
60
50
3
0
0.5
1
1.5
2
LOAD CURRENT (A)
2.5
CCM
BURST
DCM
3
DC1477B/LTM4609 EFFICIENCY AT 30V
IN
Input
100
90
EFFICIENCY (%)
80
70
60
50
0
0.5
1
1.5
2
LOAD CURRENT (A)
2.5
CCM
BURST
DCM
DC1477B/LTM4609 EFFICIENCY AT 36V
IN
Input
100
90
EFFICIENCY (%)
80
70
60
50
3
0
0.5
1
1.5
2
LOAD CURRENT (A)
2.5
CCM
PS
DCM
3
Figure 3. Measured Efficiency at Different V
IN
4
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DEMO MANUAL DC1477B
Quick start proceDure
V
OUT
(500mV/DIV)
V
OUT
(200mV/DIV)
I
OUT
STEP (1A/DIV)
I
OUT
STEP (1A/DIV)
V
IN
= 10V, V
OUT
= 30V, CCM MODE
1.5A to 3A LOAD STEP
C
OUT
= 2
×
10µF CERAMIC + 2
×
100µF ALUM
V
IN
= 36V, V
OUT
= 30V, CCM MODE
1.5A to 3A LOAD STEP
C
OUT
= 2
×
10µF CERAMIC + 2
×
100µF ALUM
Figure 4. Measured Load Transient Response (1.5A Step, 50% to 100%)
V
IN
(1V/DIV)
V
IN
(1V/DIV)
SW2 (10V/DIV)
SW2 (10V/DIV)
SW1 (20V/DIV)
SW1 (20V/DIV)
V
IN
= 10V, V
OUT
= 30V, I
OUT
= 3A
W/O INPUT FILTER: SHORT L2 AND L3, REMOVE C
IN2
V
IN
= PEAK-TO-PEAK RIPPLE = 2.78V
V
IN
= 10V, V
OUT
= 30V, I
OUT
= 3A
W/ INPUT FILTER: STUFF L2, L3, AND C
IN2
V
IN
PEAK-TO-PEAK RIPPLE = 0.47V
Figure 5. Input Voltage Ripple Measured at C
IN1
with 300MHz BW Probe, with and without the Input Filter
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