OKL2-T/3-W12P-C 查看數據表（PDF） - Murata Power Solutions
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OKL2-T/3-W12P-C Datasheet PDF : 17 Pages
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TO
OSCILLOSCOPE
CURRENT
PROBE
+VIN
+
LBUS
VIN –
+
CBUS
CIN
–
-VIN
CIN = 2 x 100μF, ESR < 700mΩ @ 100kHz
CBUS = 1000μF, ESR < 100mΩ @ 100kHz
LBUS = 1μH
Figure 4. Measuring Input Ripple Current
OKL-T/3-W12 Series
Programmable Output 3-Amp iLGA SMT PoLs
+VOUT
C1
-VOUT
C2
SCOPE
RLOAD
C1 = 1μF
C2 = 10μF
LOAD 2-3 INCHES (51-76mm) FROM MODULE
Figure 5. Measuring Output Ripple and Noise (PARD)
Minimum Output Loading Requirements
All models regulate within specification and are stable under no load to full
load conditions. Operation under no load might however slightly increase
output ripple and noise.
Thermal Shutdown
To prevent many over temperature problems and damage, these converters
include thermal shutdown circuitry. If environmental conditions cause the
temperature of the DC/DC’s to rise above the Operating Temperature Range
up to the shutdown temperature, an on-board electronic temperature
sensor will power down the unit. When the temperature decreases below
the turn-on threshold, the converter will automatically restart. There is a
small amount of hysteresis to prevent rapid on/off cycling.
CAUTION: If you operate too close to the thermal limits, the converter
may shut down suddenly without warning. Be sure to thoroughly test your
application to avoid unplanned thermal shutdown.
Temperature Derating Curves
The graphs in this data sheet illustrate typical operation under a variety of
conditions. The Derating curves show the maximum continuous ambient air
temperature and decreasing maximum output current which is accept-
able under increasing forced airflow measured in Linear Feet per Minute
(“LFM”). Note that these are AVERAGE measurements. The converter will
accept brief increases in current or reduced airflow as long as the average
is not exceeded.
Note that the temperatures are of the ambient airflow, not the converter
itself which is obviously running at higher temperature than the outside
air. Also note that very low flow rates (below about 25 LFM) are similar to
“natural convection”, that is, not using fan-forced airflow.
Murata Power Solutions makes Characterization measurements in a
closed cycle wind tunnel with calibrated airflow. We use both thermocou-
ples and an infrared camera system to observe thermal performance.
CAUTION: These graphs are all collected at slightly above Sea Level
altitude. Be sure to reduce the derating for higher density altitude.
Power Good Output
The PGood signal is an open drain output requiring a user’s external pullup
resistor to +5V or less referred to -Vin. PGood indicates when the converter
has stabilized and the output is approximately within regulation. PGood is
TRUE (open drain, high impedance state) if the converter’s power output
voltage within about +/-10% of the setpoint. When PGood is FALSE (satu-
rated low impedance state, LOW), the output resides within about +0.4V or
less referred to -Vin, depending on the pullup current.
Note that PGood does not directly measure an output overcurrent condi-
tion. However, gross overcurrent or output short circuit will set PGood to
FALSE (less than +0.4V saturation, low impedance condition). Because of
the open drain design, several converters may connect their PGood’s in
parallel with a common external pullup resistor in a wired-OR method.
The following conditions will render PGood as FALSE (Low):
+Vout is greater than 10% error from Vset.
Softstart is active and not yet complete.
An input undervoltage is present at +Vin.
An output short circuit has occurred.
An over temperature (OT) condition has occurred.
At power up, before the converter has achieved stable regulation, PGood
approximates a forward-biased diode to ground.
CAUTION - PGood is connected directly to the PWM controller and a
small signal FET inside the PWM. Use electrostatic protection. The PWM
may be destroyed by inadvertant static discharge or excess current into
the PGood signal. Pull down current should be limited to 5 mA maximum
and the external pullup voltage should never exceed +5V referred to the
negative input, -Vin.
www.murata-ps.com/support
MDC_OKL-T/3-W12 Series.C02 Page 14 of 17
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