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参数资料
| 型号： | LSN2-T/22-D12NB-C |
| 厂商： | MURATA POWER SOLUTIONS INC |
| 元件分类： | 电源模块 |
| 英文描述： | DC-DC REG PWR SUPPLY MODULE |
| 封装： | ROHS COMPLIANT, SIP-9 |
| 文件页数： | 11/13页 |
| 文件大小： | 1173K |
| 代理商： | LSN2-T/22-D12NB-C |
LSN2-T/22-D12
Non-isolated, DOSA-SIP,
22A Selectable-Output DC/DC Converters
Technical enquiries email: sales@murata-ps.com, tel: +1 508 339 3000
www.murata-ps.com
MDC_LSN2-T/22-D12_B02 Page 7 of 13
Output Adjustments
The LSN2 series includes a special output voltage trimming feature which
is fully compatible with competitive units. The output voltage may be varied
using a single trim resistor from the Trim input to Power Common (pin 4)
or an external DC trim voltage applied between the Trim input and Power
Common.
As with other trim adjustments, be sure to use a precision low-tempco resis-
tor (±100 ppm/°C) mounted close to the converter with short leads. Also be
aware that the output voltage accuracy is ±2% (typical) therefore you may
need to vary this resistance slightly to achieve your desired output setting.
Resistor Trim Equation:
VOUT
0.8V
1.0V
1.2V
1.5V
1.8V
2.5V
3.3V
5V
RTRIM (kW) Open 41.424 22.46
13.05
9.024
5.009
3.122
1.472
Voltage Trim
The LSN2 Series may also be trimmed using an external voltage applied
between the Trim input and Output Common. Be aware that the internal “load”
impedance looking into trim pin is less than 5k
W. Therefore, you may have to
compensate for this in the source resistance of your external voltage refer-
ence.
Use a low noise DC reference and short leads. Mount the leads close to the
converter. Consider using a small bypass capacitor (0.1F ceramic) between
trim and output common to improve stability.
Voltage Trim Equation:
VTRIM (in Volts) = 0.7 –(0.0667 x (VO – 0.7525))
The LSN2 fixed trim voltages to set the output voltage are:
VOUT
0.8V
1.0V
1.2V
1.5V
1.8V
2.5V
3.3V
5V
VTRIM (V)
Open
0.6835 0.670
0.650
0.630
0.583
0.530 0.4166
The highest temperatures in LSN2 SIPs 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 varying the load
to keep that temperature below +110°C under the assorted conditions 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 about +110°C.
As you may deduce from the derating curves and observe in the efficiency
curves on the following pages, LSN2 SIPs maintain virtually constant
efficiency from half to full load, and consequently deliver very impressive
temperature performance even if operating at full load.
Lastly, when LSN2 SIPs 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 demand-
ing temperature conditions, we advise you to monitor the output-inductor
temperature to ensure it remains below +110°C at all times.
Pre-Biased Startup
Newer systems with multiple power voltages have an additional problem
besides startup sequencing. Some sections have power already partially
applied (possibly because of earlier power sequencing) or have leakage power
present so that the DC/DC converter must power up into an existing voltage.
This power may either be stored in an external bypass capacitor or supplied
by an active source.
This “pre-biased” condition can also occur with some types of program-
mable logic or because of blocking diode leakage or small currents passed
through forward biased ESD diodes. Conventional DC/DC’s may fail to start up
correctly if there is output voltage already present. And some external circuits
are adversely affected when the low side MOSFET in a synchronous rectifier
converter sinks current at start up.
The LSN2 series includes a pre-bias startup mode to prevent these initializa-
tion problems. Essentially, the converter acts as a simple buck converter until
the output reaches its set point voltage at which time it converts to a synchro-
nous rectifier design. This feature is variously called “monotonic” because
the voltage does not decay (from low side MOSFET shorting) or produce a
negative transient once the input power is applied and the startup sequence
begins.
Don’t Use Pre-Biasing and Sequencing Together
Normally, you would use startup sequencing on multiple DC/DC’s to solve the
Pre-Bias problem. By causing all power sources to ramp up together, no one
source can dominate and force the others to fail to start. For most applica-
tions, do not use startup sequencing in a Pre-Bias application, especially with
an external active power source.
If you have active source pre-biasing, leave the Sequence input open so that
the output will step up quickly and safely. A symptom of this condition is
repeated failed starts. You can further verify this by removing the existing load
and testing it with a separate passive resistive load which does not exceed full
current. If the resistive load starts successfully, you may be trying to drive an
external pre-biased active source.
It may also be possible to use pre-bias and sequencing together if the Pre-
Bias source is in fact only a small external bypass capacitor slowly charged by
leakage currents. Test your application to be sure.
RTRIM (
W) = _____________ –1000
VO – 0.7525
10500
Figure 6. Trim Connections
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相关代理商/技术参数 |
参数描述 |
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| LSN2-T30-D12 | 制造商:MURATA 制造商全称:Murata Manufacturing Co., Ltd. 功能描述:DOSA-SIP, 30A POL DC/DC Converters |
| LSN2-T30-D12-C | 制造商:MURATA 制造商全称:Murata Manufacturing Co., Ltd. 功能描述:DOSA-SIP, 30A POL DC/DC Converters |
| LSN2-T30-D12G-C | 制造商:MURATA 制造商全称:Murata Manufacturing Co., Ltd. 功能描述:DOSA-SIP, 30A POL DC/DC Converters |
| LSN-3.3/10-D12 | 功能描述:DC/DC转换器 33W 12V to 3.3V 10A RoHS:否 制造商:Murata 产品: 输出功率: 输入电压范围:3.6 V to 5.5 V 输入电压（标称）: 输出端数量:1 输出电压（通道 1）:3.3 V 输出电流（通道 1）:600 mA 输出电压（通道 2）: 输出电流（通道 2）: 安装风格:SMD/SMT 封装 / 箱体尺寸: |
| LSN-3.3/10-D12B | 功能描述:DC/DC转换器 33W 12V to 3.3V 10A RoHS:否 制造商:Murata 产品: 输出功率: 输入电压范围:3.6 V to 5.5 V 输入电压（标称）: 输出端数量:1 输出电压（通道 1）:3.3 V 输出电流（通道 1）:600 mA 输出电压（通道 2）: 输出电流（通道 2）: 安装风格:SMD/SMT 封装 / 箱体尺寸: |
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