DEMO MANUAL DC2166A
LTM4639
Low V
IN
20A DC/DC
µModule Step-Down Regulator
Description
Demonstration circuit 2166A features the
LTM
®
4639EY,
a 20A high efficiency, switch mode step-down power
µModule
®
regulator. The input voltage range is from
2.375V to 7V. The output voltage range is 0.6V to 5.5V.
Derating is necessary for certain V
IN
, V
OUT
, frequency and
thermal conditions. The DC2166A offers the TRACK/SS pin
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 (JP3) selects pulse-skipping
mode for noise sensitive applications or Burst Mode
®
operation in less noise sensitive applications. There is an
on board boost circuit using LT1935 to provide control
power to LTM4639 when V
IN
is less than 4.5V. LTM4639
has on board diode connected PNP transistors to monitor
its internal temperature. A temperature sensor LTC2997
converts the internal temperature to an analog voltage out-
put. The LTM4639 data sheet must be read in conjunction
with this demo manual prior to working on or modifying
demo circuit DC2166A.
Design files for this circuit board are available at
http://www.linear.com/demo/DC2166A
L,
LT, LTC, LTM, µModule, Burst Mode, 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
dc2166af
1
DEMO MANUAL DC2166A
performance summary
PARAMETER
Input Voltage Range
Output Voltages
Maximum Continuous Output Current
Operating Frequency
Efficiency
V
IN
= 3.3V, I
OUT
= 20A
Derating is necessary for certain operating conditions.
See data sheet for details.
CONDITIONS/NOTES
VALUE
2.375V to 7V
1.0V, 1.2V, 1.5V, 1.8V ± 1.5%
20ADC
500kHz
83.2% (V
OUT1
= 1.0V) (Figure 2)
85.3% (V
OUT1
= 1.2V) (Figure 2)
87.7% (V
OUT1
= 1.5V) (Figure 2)
89.1% (V
OUT1
= 1.8V) (Figure 2)
156mV (Figure 4)
Load Transient
V
IN
= 3.3V, V
OUT
= 1.0V, I
STEP
= 0A to 10A
Quick start proceDure
Demonstration circuit DC2166A is an easy way to evalu-
ate the performance of the LTM4639EY. 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:
RUN
ON
TRACK/SS
SOFT-START
MODE
CCM
V
OUT
SELECT
1.0V
CPWR SELECT
BOOST
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.
6. (Optional) LTM4639 can be synchronized to an external
clock signal. Place the JP3 jumper on EXTCLK and apply
a clock signal (0V to 5V, square wave) on the CLKIN
test point.
7. (Optional) The outputs of LTM4639 can track another
supply by setting JP1 to EXT. TRACK. If tracking external
voltage is selected, the corresponding test point TRACK
need to be connected to a valid voltage signal.
2. With power off, connect the input power supply, load
and meters as shown in Figure 1. Preset the load to 0A
and V
IN
supply to 3.3V.
3. Turn on the power supply at the input. The output volt-
age should be 1.0V ± 1.5% (0.985V to 1.015V).
4. Vary the input voltage from 2.375V to 7V and adjust
the load current from 0A to 20A. Observe the output
voltage regulation, ripple voltage, efficiency, and other
parameters.
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dc2166af
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