LSN10A-D5 Datasheet, PDF (6/15 Pages) Murata Manufacturing Co., Ltd. – Non-Isolated, 5VIN, 1-3.8VOUT 10 Amp DC/DC In SIP Package

Single Output LSN-10A Models
Non-Isolated, 5VIN, 1-3.8VOUT
10 Amp DC/DC In SIP Package
should be used. To prevent high frequency voltage differences between VOUT
and Sense, we recommend installation of a 1000pF capacitor close to the
converter.
The sense function is capable of compensating for voltage drops between
the +Output and +Sense pins that do not exceed 10% of VOUT.
[VOUT(+) – Common] – [Sense(+) – Common] b 10%VOUT
Power derating (output current limiting) is based upon maximum output cur-
rent and voltage at the converter's output pins. Use of trim and sense functions
can cause the output voltage to increase, thereby increasing output power
beyond the LSN's specified rating. Therefore:
(VOUT at pins) x (IOUT) b rated output power
The internal 10.57resistor between +Sense and +Output (see Figure 1)
serves to protect the sense function by limiting the output current flowing
through the sense line if the main output is disconnected. It also prevents
output voltage runaway if the sense connection is disconnected.
Note: Connect the +Sense pin (pin 3) to +Output (pin 4) at the DC/DC
converter pins, if the sense function is not used for remote regulation.
On/Off Control and Power-up Sequencing
The On/Off Control pin may be used for remote on/off operation. LSN D5 SIP
Series DC/DC's are designed so they are enabled when the control pin is left
open (internal pull-down to Common) and disabled when the control pin is
pulled high (+2.8V to +VIN), as shown in Figure 2 and 2a.
+INPUT
5k7
1.1k7
ON/OFF
CONTROL
0.75k7
COMMON
Figure 2. Driving the On/Off Control Pin with an Open-Collector Drive Circuit
+INPUT
Dynamic control of the on/off function is best accomplished with a mechani-
cal relay or open-collector/open-drain drive circuit. The drive circuit should
be able to sink appropriate current when activated and withstand appropriate
voltage when deactivated.
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-D5's, or if several output volt-
ages 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.
Output Overvoltage Protection
LSN D5 SIP Series DC/DC converters do not incorporate output overvoltage
protection. In the extremely rare situation in which the device’s feedback loop
is broken, the output voltage may run to excessively high levels (VOUT = VIN). 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 com-
ponents such as inductors, FET's and diodes are at the highest risk. LSN D5
SIP Series DC/DC converters incorporate an output overcurrent 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 D5'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 70mA. Once the
output short is removed, the converter will automatically restart itself.
Output Voltage Trimming
Allowable trim ranges for each model in the LSN D5 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.
2k7
5k7
1.1k7
ON/OFF
CONTROL
0.75k7
COMMON
+INPUT
COMMON
+OUTPUT
TRIM
COMMON
20k7
5-10
Turns
LOAD
Figure 2a. Inverting On/Off Control Pin Signal and Power-Up Sequencing
Figure 3. Trim Connections Using a Trimpot
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