LSN-10A D12 Models
Single Output, Non-Isolated, 12V
IN
, 1-5V
OUT,
10A, DC/DC's in SIP Packages
The on/off control function, however, can be externally inverted so that the
converter will be disabled while the input voltage is ramping up and then
"released" once the input has stabilized.
For a controlled start-up of one or more LSN-D12's, or if several output
voltages need to be powered-up in a given sequence, the On/Off Control pin
can be pulled high (external pull-up resistor, converter disabled) and then
driven low with an external open collector device to enable the converter.
+INPUT
The equations below can be used as starting points for selecting specific trim-
resistor values. Recall, untrimmed devices are guaranteed to be 1% accurate.
Adjustment beyond the specified ±10% adjustment range is not recommended.
5.6k
4.12k
ON/OFF
CONTROL
1.62k
10k
Figure 3. Trim Connections Using a Trimpot
COMMON
Figure 2a. Inverting On/Off Control Pin Signal and Power-Up Sequencing
Output Overvoltage Protection
LSN D12 SIP Series DC/DC converters do not incorporate output overvolt-
age protection. In the extremely rare situation in which the device’s feedback
loop is broken, the output voltage may run to excessively high levels (V
OUT
=
V
IN
). If it is absolutely imperative that you protect your load against any and
all possible overvoltage situations, voltage limiting circuitry must be provided
external to the power converter.
Output Overcurrent Detection
Overloading the output of a power converter for an extended period of
time will invariably cause internal component temperatures to exceed their
maximum ratings and eventually lead to component failure. High-current-
carrying components such as inductors, FET's and diodes are at the highest
risk. LSN D12 SIP Series DC/DC converters incorporate an output overcur-
rent detection and shutdown function that serves to protect both the power
converter and its load.
If the output current exceeds it maximum rating by typically 70% (17 Amps) or
if the output voltage drops to less than 98% of it original value, the LSN D12's
internal overcurrent-detection circuitry immediately turns off the converter,
which then goes into a "hiccup" mode. While hiccupping, the converter will
continuously attempt to restart itself, go into overcurrent, and then shut down.
Under these conditions, the average output current will be approximately
400mA, and the average input current will be approximately 40mA. Once the
output short is removed, the converter will automatically restart itself.
Output Voltage Trimming
Allowable trim ranges for each model in the LSN D12 SIP Series are ±10%.
Trimming is accomplished with either a trimpot or a single fixed resistor. The
trimpot should be connected between +Output and Common with its wiper
connected to the Trim pin as shown in Figure 3 below.
A trimpot can be used to determine the value of a single fixed resistor
which can then be connected, as shown in Figure 4, between the Trim pin
and +Output to trim down the output voltage, or between the Trim pin and
Common to trim up the output voltage. Fixed resistors should have absolute
TCR’s less than 100ppm/ C to ensure stability.
Note:
Install either a fixed
trim-up resistor
or a fixed trim-down
resistor depending upon
desired output voltage.
Figure 4. Trim Connections Using Fixed Resistors
Trim Equations
R
T
DOWN
(k ) =
R
T
UP
(k ) =
1.82(V
O
–
0.8)
V
O NOM
–
V
O
1.46
V
O
–
V
O NOM
X = 0.909
X = 2.49
X = 3.09
X = 4.12
–
X
–
X
LSN-1/10-D12:
LSN-1.1/10-D12:
LSN-1.2/10-D12:
LSN-1.3/10-D12:
R
T
DOWN
(k ) =
R
T
UP
(k ) =
4.64(V
O
–
0.8)
V
O NOM
–
V
O
3.72
V
O
–
V
O NOM
–
X
–
X
LSN-1.5/10-D12:
X = 13.3
LSN-1.8/10-D12:
X = 16.9
LSN-2/10-D12:
X = 15.4
R
T
DOWN
(k ) =
R
T
UP
(k ) =
7.5(V
O
–
0.8)
V
O NOM
–
V
O
6
V
O
–
V
O NOM
–
X
–
X
LSN-2.5/10-D12:
X = 20
LSN-3.3/10-D12:
X = 15
LSN-5/10-D12:
X = 10
Note: Resistor values are in k . Accuracy of adjustment is subject to
tolerances of resistors and factory-adjusted, initial output accuracy.
V
O
= desired output voltage. V
ONOM
= nominal output voltage.
Technical enquiries
email: sales@murata-ps.com, tel:
+1 508 339 3000
www.murata-ps.com
MDC_LSN10A-D12.B01
Page 5 of 12
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