LTM8032IV#PBF Linear Technology, LTM8032IV#PBF Datasheet - Page 11

• Manufacturer Part Number: LTM8032IV#PBF
• Description: IC BUCK ADJ 2A 71LGA
• Manufacturer: Linear Technology
• Series: µModuler
• Type: Point of Load (POL) Non-Isolatedr

Specifications of LTM8032IV#PBF

• Design Resources: LTM8032 Spice Model
• Output: 0.8 ~ 10 V
• Number Of Outputs: 1
• Power (watts): 20W
• Mounting Type: Surface Mount
• Voltage - Input: 3.6 ~ 36 V
• Package / Case: 71-LGA
• 1st Output: 0.8 ~ 10 VDC @ 2A
• Size / Dimension: 0.59" L x 0.35" W x 0.11" H (15mm x 9mm x 2.8mm)
• Power (watts) - Rated: 20W
• Operating Temperature: -40°C ~ 125°C
• Approvals: EN
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• 3rd Output: -
• 2nd Output: -

APPLICATIONS INFORMATION
than 56V. If BIAS power is applied from a remote or noisy
voltage source, it may be necessary to apply a decoupling
capacitor locally to the LTM8032.
Load Sharing
Two or more LTM8032s may be paralleled to produce higher
currents. This may, however, alter the EMI performance of
the LTM8032s. To do this, tie the V
pins of all the paralleled LTM8032s together. To ensure that
paralleled modules start up together, the RUN/SS pins may
be tied together, as well. Synchronize the LTM8032s to an
external clock to eliminate beat frequencies, if required. If
the RUN/SS pins are not tied together, make sure that the
same valued soft-start capacitors are used for each module.
An example of two LTM8032 modules confi gured for load
sharing is given in the Typical Applications section.
Burst Mode Operation
To enhance effi ciency at light loads, the LTM8032 auto-
matically switches to Burst Mode operation which keeps
the output capacitor charged to the proper voltage while
minimizing the input quiescent current. During Burst Mode
operation, the LTM8032 delivers single cycle bursts of
current to the output capacitor followed by sleep periods
where the output power is delivered to the load by the output
capacitor. In addition, V
reduced to typically 20μA and 50μA respectively during
the sleep time. As the load current decreases towards a
no-load condition, the percentage of time that the LTM8032
operates in sleep mode increases and the average input
current is greatly reduced, resulting in higher effi ciency.
Burst Mode operation is enabled by tying SYNC to GND. To
disable Burst Mode operation, tie SYNC to a stable voltage
above 0.7V. Do not leave the SYNC pin fl oating.
Minimum Input Voltage
The LTM8032 is a step-down converter, so a minimum
amount of headroom is required to keep the output in
regulation. In addition, the input voltage required to turn
on is higher than that required to run, and depends upon
whether the RUN/SS is used. As shown in Figure 1, it
takes only about 3.6V
output at light load. If RUN/SS is pulled up to V
IN
IN
and BIAS quiescent currents are
for the LTM8032 to run a 3.3V
IN
, ADJ, V
OUT
and SHARE
IN
, it takes
5.5V
pin, the minimum voltage to start at light loads is lower,
about 4.5V. A similar curve for 5V
provided in Figure 1.
Soft-Start
The RUN/SS pin can be used to soft-start the LTM8032,
reducing the maximum input current during start-up. The
RUN/SS pin is driven through an external RC network to
create a voltage ramp at this pin. Figure 2 shows the start-
up and shutdown waveforms with the soft-start circuit. By
choosing an appropriate RC time constant, the peak start-up
current can be reduced to the current that is required to
regulate the output, with no overshoot. Choose the value
of the resistor so that it can supply at least 20μA when
the RUN/SS pin reaches 2.5V.
Figure 1. The LTM8032 Needs More Voltage to Start Than Run
IN
to start. If the LTM8032 is enabled via the RUN/SS
6.0
5.5
5.0
4.5
4.0
3.5
3.0
7.5
7.0
6.0
5.5
5.0
6.5
0
0
V
V
OUT
OUT
= 5V
= 3.3V
500
500
LOAD CURRENT (mA)
LOAD CURRENT (mA)
1000
1000
TO RUN
TO START
RUN/SS ENABLED
TO RUN
TO START
RUN/SS ENABLED
1500
1500
OUT
LTM8032
8032 F01a
8032 F01b
operation is also
2000
2000
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