LSM16A-D12 Datasheet, PDF (7/12 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
Output Reverse Conduction
Many DC/DCs 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.
LSM D12 SMT DC/DC converters do not suffer from Output Reverse Conduc-
tion. They employ proprietary gate drive circuitry that makes them immune to
applied output voltages.
Thermal Considerations and Thermal Protection
The typical output-current thermal-derating curves shown below enable
designers to determine how much current they can reliably derive from each
model of the LSM D12 SMTs under known ambient-temperature and air-flow
conditions. Similarly, the curves indicate how much air flow is required to reli-
ably deliver a specific output current at known temperatures.
The highest temperatures in LSM D12 SMTs occur at their output inductor,
whose heat is generated primarily by I²R losses. The derating curves were
developed using thermocouples to monitor the inductor temperature and vary-
ing the load to keep that temperature below +110°C under the assorted condi-
tions of air flow and air temperature. Once the temperature exceeds +115°C
(approx.), the thermal protection will disable the converter. Automatic restart
occurs after the temperature has dropped below +110°C.
As you may deduce from the derating curves and observe in the efficiency
curves on the following pages, LSM D12 SMT's maintain virtually constant
efficiency from half to full load, and consequently deliver very impressive
temperature performance even if operating at full load.
Lastly, when LSM D12 SMT's are installed in system boards, they are
obviously subject to numerous factors and tolerances not taken into account
here. If you are attempting to extract the most current out of these units under
demanding temperature conditions, we advise you to monitor the output-
inductor temperature to ensure it remains below +110°C at all times.
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