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LSN16A-W3 Datasheet, PDF (6/8 Pages) Murata Manufacturing Co., Ltd. – Non-Isolated, 3-5.5VIN, 0.75-3.3VOUT 16 Amp DC/DC Converters
◁
Single Output LSN-W3 Models
Non-Isolated, 3-5.5VIN, 0.75-3.3VOUT
16 Amp DC/DC Converters
+INPUT
COMMON
+OUTPUT
TRIM
COMMON
Trim
Down
Trim
Up
LOAD
Note: Install either a fixed
trim-up resistor or a fixed
trim-down resistor depending
on desired output voltage.
Figure 7. Trim Connections Using Fixed Resistors
A trimpot can be used to determine the value of a single fixed resistor
which can then be connected, as shown in Figure 7, 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/oC to ensure stability.
The equations below can be starting points for selecting specific trim-resistor
values. Recall, untrimmed devices are guaranteed to be ±1% accurate.
Trim Equations
4RIM$OWN
,3.  7
4RIM5P
Adjustment beyond the specified ±10% adjustment range is not recom-
mended. When using trim in combination with Remote Sense, the maximum
rated power must not be exceeded (see Remote Sense).
“T” Model (LSN-T/16-W3)
This version of the the LSN-W3 series offers a special output voltage trim-
ming feature which is fully compatible with competitive units. The output
voltage may be varied using a single trim resistor from the Trim Input to Power
Common. The output voltage range is 0.75 Volts to 3.3 Volts.
IMPORTANT: For outputs greater than 3 Volts up to 3.3 Volts maximum, the
input supply must be 4.5 Volts minimum.
As with other trim adjustments, be sure to use a precision low-tempco
resistor (±100 ppm/°C) mounted close to the converter with short leads. Also
be aware that the output voltage accuracy is ±2% (typical) therefore you may
need to vary this resistance slightly to achieve your desired output setting.
The trim equation is as follows for the LSN-T/16-W3:
RTRIM (7) = _____2_1_0_7_0____ –5110
VO – 0.7525
LSN-T/16-W3 fixed resistance values to set the output voltages are:
.O4RIM$OWN
4"$
,3.  7
6/n
24$/7.K7 
n6/
n

2450K7  6/n n
,3.  7
24$/7.K7 
6/n
n6/
n

2450K7 
n
6/n
,3.  7
6/n
24$/7.K7 
n
n6/

2450K7 
n
6/n
,3.  7
6/n
24$/7.K7 
n6/
n

2450K7 
n
6/n
,3.  7
6/n
24$/7.K7  n6/
n

2450K7 
n
6/n
,3.  7
6/n
24$/7.K7  n6/
n

2450K7 
n
6/n
,3.  7
6/n
24$/7.K7  n6/
n

2450K7 
n
6/n
Note: Resistor values are in k7. Accuracy of adjustment is subject to toler-
ances of resistors and factory-adjusted, initial output accuracy. VO = desired
output voltage. VONOM = nominal output voltage.
VOUT (Typ.) 0.75V 1.0V 1.2V 1.5V 1.8V 2.5V 3.3V
RTRIM (kΩ) Open 80.021 41.973 23.077 15.004 6.947 3.16
CAUTION: To retain proper regulation, do not exceed the 3.3V output
Voltage Trim
The LSN-T/16-W3 may also be trimmed using an external voltage applied
between the Trim input and Output Common. Be aware that the internal “load”
impedance looking into the Trim pin is approximately 5k7. Therefore, you may
have to compensate for this in the source resistance of your external voltage
reference.
The equation for this voltage adjustment is:
VTRIM (in Volts) = 0.7 –(0.1698 x (VO – 0.7525))
The LSN-T/16-W3 fixed trim voltages to set the output voltage are:
VOUT (Typ.) 0.75V 1.0V 1.2V 1.5V 1.8V 2.5V 3.3V
VTRIM Open 0.6928V 0.624V 0.5731V 0.5221V 0.4033V 0.267V
Output Reverse Conduction
Many DC/DC’s using synchronous rectification suffer from Output Reverse
Conduction. If those devices have a voltage applied across their output before
a voltage is applied to their input (this typically occurs when another power
supply starts before them in a power-sequenced application), they will either
fail to start or self destruct. In both cases, the cause is the “freewheeling” or
“catch” FET biasing itself on and effectively becoming a short circuit.
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Technical enquiries email: sales@murata-ps.com, tel: +1 508 339 3000
MDC_LSN W3 Models.A01 Page 6 of 8
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