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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OKL-T/3-W12 Series
Programmable Output 3-Amp iLGA SMT PoLs
drop, thereby shutting down the PWM controller. Following a time-out period,
the PWM will restart, causing the output voltage to begin rising to its appropri-
ate value. If the short-circuit condition persists, another shutdown cycle will
initiate. This rapid on/off cycling is called “hiccup mode”. The hiccup cycling
reduces the average output current, thereby preventing excessive internal
temperatures and/or component damage.
The “hiccup” system differs from older latching short circuit systems
because you do not have to power down the converter to make it restart. The
system will automatically restore operation as soon as the short circuit condi-
tion is removed.
Remote On/Off Control
The OKL Series power modules can be specified with either a positive or negative
logic type. See Figures 7 and 8 for On/Off circuit control. In the positive logic on/off
option the unit turns on during a logic high on the On/Off pin and turns off during a
logic low. In a negative logic on/off option, the unit turns off during logic high and
on during logic low. The On/Off signal should always be reference to ground. For
positive or negative option, leaving then On/Off pin disconnected will turn the unit
on when input voltage is present.
Positive—Units are enabled when the on/off pin is left open or is pulled high
to +Vin. The On/Off circuit control is shown in figure 7. When the external tran-
sistor Q1 is in the off state, the internal PWM enable pin is pull high causing the
unit to turn on. When Q1 is turn on, the On/Off pin is pulled low and the units is
off. Rp should be around 20K ohms.
Negative—Units are enabled when the ON/Off is open or brought to within
a low voltage (see specifications) with respect to –Vin. The unit is off when
the ON/Off is pulled high with respect to –Vin (see specifications). The On/
Off circuitry is shown in figure 8. The On/Off pin should be pulled high with an
external pull-up resistor (20K ohms). When Q1 is in the off state, the On/Off pin
is pulled high, transistor Q3 is turn on and the unit is off. To turn on the unit,
Q1 is turn on, pulling the On/Off pin low and turning Q3 off resulting on the unit
being on.
Dynamic control of the On/Off function should be able to sink the speci-
fied signal current when brought low and withstand appropriate voltage when
brought high. Be aware too that there is a finite time in milliseconds (see speci-
fications) between the time of On/Off Control activation and stable, regulated
output. This time will vary slightly with output load type and current and input
conditions.
Output Capacitive Load
These converters do not require external capacitance added to achieve
rated specifications. Users should only consider adding capacitance to reduce
switching noise and/or to handle spike current load steps. Install only enough
capacitance to achieve noise objectives. Excess external capacitance may
cause regulation problems, degraded transient response and possible oscilla-
tion or instability.
OKL N Module
+Vin
+Vin
Rp
On/Off
Q1
E
Q3
PWM
GND
GND
GND
BOM Rp 20K
BOM Q1 Q SMT MOS P 30V
Figure 8. On/Off Circuit Control for Using Negative On/Off Logic
Soldering Guidelines
Murata Power Solutions recommends the specifications below when installing these
converters. These specifications vary depending on the solder type. Exceeding these
specifications may cause damage to the product. Your production environment may differ
therefore please thoroughly review these guidelines with your process engineers.
Reflow Solder Operations for surface-mount products (SMT)
For Sn/Ag/Cu based solders:
Preheat Temperature
Less than 1 ºC. per second
Time over Liquidus
45 to 75 seconds
Maximum Peak Temperature 260 ºC.
Cooling Rate
Less than 3 ºC. per second
For Sn/Pb based solders:
Preheat Temperature
Less than 1 ºC. per second
Time over Liquidus
60 to 75 seconds
Maximum Peak Temperature 235 ºC.
Cooling Rate
Less than 3 ºC. per second
250
Peak Temp.
235-260° C
200
150
100
50
0
0
<1.5° C/sec
Soaking Zone
120 sec max
Preheating Zone
240 sec max
Reflow Zone
time above 217° C
45-75 sec
High trace = normal upper limit
Low trace = normal lower limit
30
60
90
120
150
180
210
240
270
300
Time (sec)
Recommended Lead-free Solder Reflow Profile
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MDC_OKL-T/3-W12 Series.C02 Page 16 of 17
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