LSM-1.2/10-D12-C Murata Power Solutions Inc, LSM-1.2/10-D12-C Datasheet - Page 9

• Manufacturer Part Number: LSM-1.2/10-D12-C
• Description: DC/DC SM 10A 12-1.2V Non-Iso
• Manufacturer: Murata Power Solutions Inc
• Series: LSMr

Specifications of LSM-1.2/10-D12-C

• Product: Non-Isolated / POL
• Output Power: 12 W
• Input Voltage Range: 10.8 V to 13.2 V
• Number Of Outputs: 1
• Output Voltage (channel 1): 1.2 V
• Output Current (channel 1): 10 A
• Output Type: Low Voltage
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant

(DVM), the voltage may appear to be adequate. Limited external capacitance
and/or too high a source impedance may cause a short downward spike at
power up, causing an instantaneous voltage drop. Use an oscilloscope not a
DVM to observe this spike. The converter’s soft-start controller is sensitive to
input voltage. What matters here is the actual voltage at the input terminals at
all times.
tion or brief start up then overcurrent shutdown. Since the input voltage is never
absolutely constant, the converter may start up some times and not others.
Solutions
To improve start up, review the conditions above. One of the better solutions is
to place a moderate size capacitor very close to the input terminals. You may
need two parallel capacitors. A larger electrolytic or tantalum cap supplies the
surge current and a smaller parallel low-ESR ceramic cap gives low AC imped-
ance. Too large an electrolytic capacitor may have higher internal impedance
(ESR) and/or lower the start up slew rate enough to upset the DC/DC’s control-
ler. Make sure the capacitors can tolerate reflected switching current pulses
from the converter.
converter which starts successfully at 3.3 Volts will turn off if the input voltage
decays to below the input voltage theshold, regardless of external capacitance.
If you measure the input voltage before start up with a Digital Voltmeter
Symptoms of start-up difficulties may include failed started, output oscilla-
The capacitors will not help if the input source has poor regulation. A
Typical Performance Curves for LSM D12 SMT Series
www.murata-ps.com
spike. Also, make sure that the input voltage ramps up in a reasonably short
time (less than a few milliseconds). If possible, move the input source closer to
the converter to reduce ohmic losses in the input wiring. Remember that the
input current is carried both by the wiring and the ground plane return. Make
sure the ground plane uses adequate thickness copper. Run additional bus wire
if necessary.
more) to reduce output noise at the load and to avoid marginal threshold noise
problems with external logic. An output cap will also “decouple” inductive reac-
tance in the load. Certain kinds of electronic loads include “constant current”
characteristics which destabilize the output with insufficient capacitance. If the
wiring to the eventual load is long, consider placing this decoupling cap at the
load. Use the Remote Sense input to avoid ohmic voltage drop errors.
the Remote On/Off control first in the off setting (for those converters with an
On/Off Control). After the specified start-up delay (usually under 20 mSec), turn
on the converter. The controller will have already been stabilized. The short
delay will not be noticed in most applications. Be aware of applications which
need “power management” (phased start up).
fidelity. How low is the resistance of your ground plane? What is the inductance
(and distributed capacitance) of external wiring? Even a detailed mathematical
model may not get all aspects of your circuit. Therefore it is difficult to give cap
values which serve all applications. Some experimentation may be required.
Increase the input start up voltage if possible to raise the downward voltage
Any added output capacitor should use just enough capacitance (and no
An elegant solution to start up problems is to apply the input voltage with
Finally, it is challenging to model some application circuits with absolute
Non-Isolated, 12V
Technical enquiries email: [e-mail], tel:
IN
LSM-10A D12 Models
, 0.75-5V
MDC_LSM 10A D12 Models.B01 Page 9 of 18
Single Output
OUT
DC/DC Converters
[phone]