LSN16A-W3 Datasheet, PDF (5/8 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
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: If the sense function is not used for remote regulation, +Sense (pin 3)
must be tied to +Output (pin 4) at the DC/DC converter pins.
On/Off Control and Power-up Sequencing
The On/Off Control pin may be used for remote on/off operation. LSN W3 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 (+2.5V to +VIN), as shown in Figures 4 and 5.
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.
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Figure 4. Driving the On/Off Control Pin with an Open-Collector Drive Circuit
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-W3’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 W3 Series DC/DC converters do not incorporate output overvoltage protec-
tion. 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 power converter’s output for an extended 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 W3 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 50% (24 Amps)
or if the output voltage drops to less than 98% of it original value, the LSN W3’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 W3 Series are ±10%. Trim-
ming 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 6 below.
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Figure 5. Inverting On/Off Control Pin Signal and Power-Up Sequencing
www.murata-ps.com
Figure 6. Trim Connections Using a Trimpot
Technical enquiries email: [e-mail], tel: [phone]
MDC_LSN W3 Models.A01 Page 5 of 8