LSM16A-D12 Datasheet, PDF (6/12 Pages) Murata Manufacturing Co., Ltd. – Non-Isolated, 13-80W SMT DC/DC Converters

LSM-16A D12 Models
Non-Isolated, 13-80W SMT DC/DC Converters
+INPUT
COMMON
+OUTPUT
TRIM
COMMON
Trim
Down
LOAD
Trim
Up
Figure 7. Trim Connections Using Fixed Resistors
The equations below can be starting points for selecting specific trim-resistor
values. Recall, untrimmed devices are guaranteed to be ±1.25% accurate.
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).
Trim Equations
7.87(VO – 0.7)
RT (k7) =
–X
DOWN
VO _NOM – VO
5.509
RT_UP (k7) = _{VO – VO NOM} – X
Where: VO = Desired Output Voltage
VO _NOM = Nominal Output Voltage
LSM-0.75/16-D12:
LSM-1/16-D12:
LSM-1.2/16-D12:
LSM-1.5/16-D12:
LSM-1.8/16-D12:
LSM-2/16-D12:
LSM-2.5/16-D12:
LSM-3.3/16-D12:
LSM-5/16-D12:
X = 0.909
X = 11.5
X = 19.1
X = 27.4
X = 16.9
X = 21.5
X = 18.2
X = 13.7
X = 9.09
Note: Resistor values are in kΩ. Accuracy of adjustment is subject
to tolerances of resistors and factory-adjusted, initial output accuracy.
VO = desired output voltage. VONOM = nominal output voltage.
“T” Model LSM-T/16-D12
This version of the LSM 16A series offers a special output voltage trimming
feature which is fully compatible with competitive units. The output voltage
may be varied from 0.75 to 5 Volts using a single external trim-up resistor con-
nected from the Trim input to Output Common. If no trim resistor is attached
(Trim pin open), the output is 0.7525 Volts.
The trim may also be adjusted using an external reference voltage con-
nected to the Trim input.
As with other trim adjustments, use a 1% metal film precision resistor with
low temperature coefficient (±100 ppm/°C or less) mounted close to the con-
verter with short leads. Also be aware that the output accuracy is ±2% (typical)
therefore you may need to vary this resistance slightly to achieve your desired
output setting.
The resistor trim up equation for the LSM-T/16-D12 is as follows:
10500
RT_UP (7) =
– 1000
VO – 0.7525
Where VO is the desired output voltage.
The LSM-T/16-D12 fixed resistance values to set the output values are:
VO 0.7525V 1.0V 1.2V 1.5V 1.8V 2.5V 3.3V 5.0V
RT (kΩ) Open 41.424 22.46 13.05 9.024 5.009 3.122 1.472
CAUTION: To retain proper regulation, do not exceed the 5 Volt output.
Voltage Trim
The LSM-T/16-D12 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 trim pin is approximately 5kΩ. 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 = 0.7 – (0.0667 × (VO – 0.7525))
The LSM-T/16-D12 fixed trim voltages to set the output voltage are:
VO 0.7525V 1.0V 1.2V 1.5V 1.8V 2.5V 3.3V 5.0V
VT (V) Open 0.6835 0.670 0.650 0.630 0.583 0.530 0.4166
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MDC_LSM 16A D12 Models.A05 Page 6 of 12