 |
|
| If you can't view the Datasheet, Please click here to try to view without PDF Reader . |
|
|
|
| If you can't view the Datasheet, Please click here to try to view without PDF Reader . |
|
|
| Datasheet File OCR Text: |
| www.murata-ps.com PRODUCT OVERVIEW Featuring a full 25 Watt output in one square inch of board area, the UEI25 series isolated DC/DC converter family offers efficient regulated DC power for printed circuit board mounting. The 0.96" x 1.1" x 0.32" (24.38 x 27.94 x 8.13 mm) converter accepts a 2:1 input voltage range of 36 to 75 Volts DC, ideal for telecom equipment. The industry-standard pinout fits larger 1" x 2" converters. The fixed output voltage is tightly regulated. Applications include small instruments, area-limited microcontrollers, data communications equipment, remote sensor systems, telephone equipment, vehicle and portable electronics. The UEI25 series includes full magnetic and optical isolation with Basic protection up to 2250 Volts DC. For powering digital systems, the outputs offer UEI25-120 Series Single Output Isolated 25-Watt DC/DC Converters Typical unit FEATURES Small footprint DC/DC converter, ideal for high current applications Industry standard 0.96" x 1.1" x 0.32" open frame package and pinout Input voltage range of 36-75 Vdc 12Vdc fixed output Assembly and attachment for RoHS standards Isolation up to 2250 VDC (basic) Up to 25 Watts total output power with overtemperature shutdown High efficiency synchronous rectifier forward topology Stable operation with no required external components Usable -40 to 85C temperature range (with derating) Certified to UL/EN 60950-1, CSA-C22.2 No. 60950-1, 2nd edition safety approvals (certification is pending) Extensive self-protection shut down features fast settling to step transients and will accept higher capacitive loads. Excellent ripple and noise specifications assure compatibility to noise-susceptible circuits. For systems requiring controlled startup/ shutdown, an external remote On/Off control may use a switch, transistor or digital logic. A wealth of self-protection features avoid both converter and external circuit faults. These include input undervoltage lockout and overtemperature shutdown. The outputs current limit using the "hiccup" autorestart technique and the outputs are short-circuit protected. Additional features include output overvoltage and reverse conduction elimination. The high efficiency offers minimal heat buildup and "no fan" operation. Contents Description, Photograph, Connection Diagram Ordering Guide, Model Numbering Mechanical Specifications, Input/Output Pinout UEI25-120-D48 Specifications and Performance Data Application Notes Page 1 2 3 4 8 F1 +Vin (1) Barrier +Vout (3) External DC Power Source On/Off Control (6) Controller and Power Open = On Reference and Error Amplifier Trim (4) polarity) -Vin (2) -Vout (5) Figure 1. Connection Diagram Typical topology is shown. Murata Power Solutions recommends an external fuse. For full details go to www.murata-ps.com/rohs (certification is pending) www.murata-ps.com 17 Aug 2010 email: sales@murata-ps.com MDC_UEI25-120.A02 Page 1 of 11 UEI25-120 Series Single Output Isolated 25-Watt DC/DC Converters PERFORMANCE SPECIFICATIONS AND ORDERING GUIDE Output R/N (mVp-p) Root Models UEI25-120-D48 Input Regulation (Max.) IIN, min. VIN Nom. Range load (V) (V) (mA) 48 36-75 20 IOUT Total VOUT (A, Power (V) max) (W) Typ. Max. 12 2.1 25.2 95 120 Line 0.1% Load 0.1% IIN, full load (A) 0.6 Efficiency Package, C75 Min. Typ. Case (inches) 0.96x1.1x0.32 Case (mm) 24.38x27.94x8.13 Pinout P85 86.0% 87.5% Notes: Please refer to the part number structure for additional options and complete ordering part numbers. Ripple and Noise is shown at 20 MHz bandwidth. All specifications are at nominal line voltage and full load, +25 deg.C. unless otherwise noted. See detailed specifications for full conditions. (Note Continued) Output capacitors are 1 F ceramic in parallel with 10 F electrolytic. The input cap is 47 F ceramic, low ESR. I/O caps are necessary for our test equipment and may not be needed for your application. UL certification is pending. PART NUMBER STRUCTURE UEI25 - 120 - D48 P Lx - C Unipolar Ouput Isolated 25-Watt Series Nominal Output Voltage in Tenths of a Volt RoHS-6 Hazardous Substance Compliance (Does not claim EU RoHS exemption 7b, lead in solder) Pin Length Option Blank = Std. pin length 0.25 (6.3mm) L1 = 0.110 (2.79mm)* L2 = 0.145 (3.68mm)* On/Off Control Polarity: P = Positive N = Negative Note: Some model number combinations may not be available. Contact Murata Power Solutions. Input Voltage Range D48 = 36-75 Vdc *Alternate pin lengths require quantity order. www.murata-ps.com 17 Aug 2010 email: sales@murata-ps.com MDC_UEI25-120.A02 Page 2 of 11 UEI25-120 Series Single Output Isolated 25-Watt DC/DC Converters MECHANICAL SPECIFICATIONS Dimensions are in inches (mm shown for ref. only). Case 75 Third Angle Projection 24.4 0.96 PIN #1 Tolerances (unless otherwise specified): .XX 0.02 (0.5) .XXX 0.010 (0.25) Angles 1 Components are shown for reference only. 27.9 1.10 TOP VIEW INPUT/OUTPUT CONNECTIONS Pin Function P85 1 2 3 4 Positive Vin Negative Vin Positive Vout Output Trim Negative Vout On/Off Control* MOUNTING PLANE SIDE VIEW 8.1 0.32 MAX 5 6 *The Remote On/Off can be provided with either positive (P suffix) or negative (N suffix) polarity .040.002 .071 .002 SHOULDER 6X AT PINS 1-6 These converters are plug-compatible to competitive units. In case of pinout numbering inconsistency, follow the pin FUNCTION, not the pin number when laying out your PC board. BOTTOM VIEW 20.32 0.800 0.58 2.54 0.100 0.41 #3 C L 5.08 0.200 #1 #2 #4 10.16 0.400 6.3 0.25 10.16 0.400 C L #5 0.15 TYP RECOMMENDED PRI-SEC BARRIER END VIEW 0.475 REF 10.16 0.400 C L 0.30 #6 Standard pin length is shown. Please refer to the Ordering Guide for alternate pin lengths. www.murata-ps.com 17 Aug 2010 email: sales@murata-ps.com MDC_UEI25-120.A02 Page 3 of 11 UEI25-120 Series Single Output Isolated 25-Watt DC/DC Converters FUNCTIONAL SPECIFICATIONS - MODEL UEI25-120-D48 ABSOLUTE MAXIMUM RATINGS Input Voltage, Continuous Input Voltage, Transient Isolation Voltage Conditions Full power operation Operating or non-operating, 100 mS max. duration Input to output tested 100 mS IEC/EN/UL 60950-1 None, install external fuse Power on or off, referred to -Vin Minimum 0 0 Typical/Nominal Maximum 75 100 2250 Units Vdc Vdc Vdc Input Reverse Polarity None Vdc On/Off Remote Control 0 15 Vdc Output Power 0 25 W Output Current Current-limited, no damage, short-circuit protected 0 2.1 A Storage Temperature Range Vin = Zero (no power) -55 125 C Absolute maximums are stress ratings. Exposure of devices to greater than any of these conditions may adversely affect long-term reliability. Proper operation under conditions other than those listed in the Performance/Functional Specifications Table is not implied or recommended. INPUT Operating voltage range Recommended External Fuse Start-up threshold Undervoltage shutdown Overvoltage shutdown Reverse Polarity Protection Internal Filter Type Input current Full Load Conditions Low Line Inrush Transient Output in Short Circuit No Load Standby Mode (Off, UV, OT) Reflected (back) ripple current Pre-biased startup 36 Fast blow Rising input voltage Falling input voltage None, install external fuse 34 32 48 1.5 35.2 34.0 None None capacitive 0.600 0.809 0.05 50 20 1 30 Monotonic 86.0 2250 basic 10 1700 Certified to UL-60950-1, CSA-C22.2 No.609501, IEC/EN60950-1 (pending) Per MIL-HDBK-217F, ground benign, Tambient=+30C Per Telcordia SR332, issue 1, class 3, ground fixed, Tambient=+40C 295 Power On to Vout regulated Remote ON to Vout regulated 50-75-50% load step, settling time to within 1% of Vout same as above Yes TBD 2 325 10 10 100 250 355 50 50 200 1 350 Hours x 106 Hours x 106 KHz mS mS Sec A/Sec mV Mohm pF 87.5 75 36 35.2 Vdc A Vdc Vdc Vdc Vdc Vin = nominal Vin = minimum 0.617 0.842 100 35 2 Iout = minimum, unit=ON Measured at input with specified filter External output voltage < Vset Vin=48V, full load Input to output, continuous to IEC/EN/UL 60950-1 A A A2-Sec. mA mA mA mA, RMS GENERAL and SAFETY Efficiency Isolation Isolation Voltage Insulation Safety Rating Isolation Resistance Isolation Capacitance Safety Calculated MTBF Calculated MTBF % Vdc DYNAMIC CHARACTERISTICS Fixed Switching Frequency Startup Time Startup Time Dynamic Load Response Dynamic load di/dt Dynamic Load Peak Deviation FEATURES and OPTIONS Remote On/Off Control "N" suffix Negative Logic, ON state Negative Logic, OFF state Control Current "P" suffix Positive Logic, ON state Positive Logic, OFF state Control Current Pin open=OFF -0.7 10 1 10 -0.7 1 15 0.8 0.7 15 V V mA V V mA Pin open=ON www.murata-ps.com 17 Aug 2010 email: sales@murata-ps.com MDC_UEI25-120.A02 Page 4 of 11 UEI25-120 Series Single Output Isolated 25-Watt DC/DC Converters FUNCTIONAL SPECIFICATIONS (CONT.) - MODEL UEI25-120-D48 OUTPUT Total Output Power Voltage Nominal Output Voltage Setting Accuracy Output Voltage Range Overvoltage Protection Current Output Current Range Minimum Load Current Limit Inception Short Circuit Short Circuit Current Short Circuit Duration (remove short for recovery) Short circuit protection method Hiccup autorestart duty cycle Regulation Line Regulation Load Regulation Ripple and Noise Temperature Coefficient Maximum Capacitive Loading (10% ceramic, 90% Oscon) Conditions See Derating No trim At 50% load User-adjustable Via magnetic feedback Minimum 0.0 11.88 -1 -10 14 0.0 Typical/Nominal 25.2 12.00 Maximum 25.45 12.12 +1 +10 22 2.1 130 0.1 Units W Vdc % of Vset. % of Vnom. Vdc A % of IoutMax A 19 2.1 No minimum load 97% of Vnom., after warmup Hiccup technique, autorecovery within 1.25% of Vout Output shorted to ground, no damage Current limiting Output shorted to ground Vin=min. to max., Vout=nom., 50% load Iout=min. to max., Vin=48V 5 Hz- 20 MHz BW At all outputs Cap. ESR=<0.02, full resistive load 110 Continuous TBD 0.075 0.05 120 470 % % of Vout % of Vout mV pk-pk % of Vnom./C F 95 0.02 0 MECHANICAL (Through Hole Models) Outline Dimensions (no baseplate) (Please refer to outline drawing) Weight Through Hole Pin Diameter Through Hole Pin Material TH Pin Plating Metal and Thickness Conditions C75 case WxLxH Minimum Typical/Nominal 0.96x1.1x0.32 24.38x27.94x8.13 0.32 9.07 0.04 1.016 Copper alloy TBD TBD Maximum Units Inches mm Ounces Grams Inches mm -inches -inches Nickel subplate Gold overplate With derating, 200 LFM Measured in center Vin = Zero (no power) Measured at hotspot External filter is required -40 -55 130 ENVIRONMENTAL Operating Ambient Temperature Range Tref Location Storage Temperature Thermal Protection/Shutdown Electromagnetic Interference Conducted, EN55022/CISPR22 Radiated, EN55022/CISPR22 Relative humidity, non-condensing Altitude RoHS rating 85 125 150 C C C Class Class %RH feet meters 135 B B To +85C must derate -1%/1000 feet 10 -500 -152 RoHS-6 90 10,000 3048 Notes Unless otherwise noted, all specifications are at nominal input voltage, nominal output voltage and full load. General conditions are +25 Celsius ambient temperature, near sea level altitude, natural convection airflow. All models are tested and specified with external parallel 1 F and 10 F multi-layer ceramic output capacitors. The external input capacitor is 4.7 F ceramic. All capacitors are low-ESR types wired close to the converter. These capacitors are necessary for our test equipment and may not be needed in the user's application. Input (back) ripple current is tested and specified over 5 Hz to 20 MHz bandwidth. Input filtering is Cbus=220 F, Cin=33 F and Lbus=12 H. All models are stable and regulate to specification under no load. The Remote On/Off Control is referred to -Vin. Regulation specifications describe the output voltage changes as the line voltage or load current is varied from its nominal or midpoint value to either extreme. www.murata-ps.com 17 Aug 2010 email: sales@murata-ps.com MDC_UEI25-120.A02 Page 5 of 11 UEI25-120 Series Single Output Isolated 25-Watt DC/DC Converters UEI25-120-D48 PERFORMANCE DATA Efficiency vs. Line Voltage and Load Current @ 25C 89 88 87 3.46 4.46 3.96 Power Dissipation vs. Load Current @ 25C 86 Efficiency (%) 85 84 83 82 Vin = 36V Vin = 48V Vin = 60V Vin = 75V Loss (Watts) ( 2.96 2.46 1.96 1.46 Vin = 36V Vin = 48V Vin = 60V Vin = 75V 81 80 79 78 0.4 0.6 0.8 0.9 1.1 1.3 1.4 1.6 1.8 1.9 2.1 0.96 0.46 0.4 0.6 0.8 0.9 1.1 1.3 1.4 1.6 1.8 1.9 2.1 Load Current (Amps) ( Load Current (Amps) Maximum Current Temperature Derating @sea level (VIN = 36V, airflow is from pin 1 to pin 3) 2.25 2.2 2.2 2.175 Maximum Current Temperature Derating @sea level (VIN = 48V, airflow is from pin 1 to pin 3) Output Current (Amps) ( Output Current (Amps) ( 2.15 2.1 2.05 65 LFM 100 LFM 200 LFM 300 LFM 2.15 2.125 2.1 2.075 2.05 2.025 65 LFM 100 LFM 200 LFM 1.95 1.9 65 70 75 A Ambient temperature (C) 80 85 2 65 70 75 A Ambient temperature (C) 80 85 Maximum Current Temperature Derating @sea level (VIN = 60V, airflow is from pin 1 to pin 3) 2.2 2.175 Maximum Current Temperature Derating @sea level (VIN = 75V, airflow is from pin 1 to pin 3) 2.2 2.15 Output Current (Amps) ( Output Current (Amps) ( 2.15 2.125 2.1 2.075 2.05 2.025 2 65 70 75 Am A bient temperature (C) 80 85 65 LFM 100 LFM 200 LFM 2.1 2.05 65 LFM 100 LFM 200 LFM 300 LFM 1.95 1.9 65 70 75 A Ambient temperature (C) 80 85 www.murata-ps.com 17 Aug 2010 email: sales@murata-ps.com MDC_UEI25-120.A02 Page 6 of 11 UEI25-120 Series Single Output Isolated 25-Watt DC/DC Converters UEI25-120-D48 OSCILLOGRAMS Stepload Transient Response (Vin = 48V, Iout = 25-75-25% of Imax, Cout = 1&10F, Ta = +25C, Scope BW = 20MHz) Output Ripple and Noise (Vin=48V, Iout = 2.1A, Cout = 1&10F, Ta = +25C, Scope BW = 20MHz) www.murata-ps.com 17 Aug 2010 email: sales@murata-ps.com MDC_UEI25-120.A02 Page 7 of 11 UEI25-120 Series Single Output Isolated 25-Watt DC/DC Converters APPLICATION NOTES Input Fusing Certain applications and/or safety agencies may require fuses at the inputs of power conversion components. Fuses should also be used when there is the possibility of sustained input voltage reversal which is not current-limited. For greatest safety, we recommend a fast blow fuse installed in the ungrounded input supply line. The installer must observe all relevant safety standards and regulations. For safety agency approvals, install the converter in compliance with the end-user safety standard. Input Reverse-Polarity Protection If the input voltage polarity is reversed, an internal diode will become forward biased and likely draw excessive current from the power source. If this source is not current-limited or the circuit appropriately fused, it could cause permanent damage to the converter. Input Under-Voltage Shutdown and Start-Up Threshold Under normal start-up conditions, converters will not begin to regulate properly until the rising input voltage exceeds and remains at the Start-Up Threshold Voltage (see Specifications). Once operating, converters will not turn off until the input voltage drops below the Under-Voltage Shutdown Limit. Subsequent restart will not occur until the input voltage rises again above the Start-Up Threshold. This built-in hysteresis prevents any unstable on/off operation at a single input voltage. Users should be aware however of input sources near the Under-Voltage Shutdown whose voltage decays as input current is consumed (such as capacitor inputs), the converter shuts off and then restarts as the external capacitor recharges. Such situations could oscillate. To prevent this, make sure the operating input voltage is well above the UV Shutdown voltage AT ALL TIMES. Start-Up Delay Assuming that the output current is set at the rated maximum, the Vin to Vout StartUp Delay (see Specifications) is the time interval between the point when the rising input voltage crosses the Start-Up Threshold and the fully loaded regulated output voltage enters and remains within its specified regulation band. Actual measured times will vary with input source impedance, external input capacitance, input voltage slew rate and final value of the input voltage as it appears at the converter. These converters include a soft start circuit to moderate the duty cycle of the PWM controller at power up, thereby limiting the input inrush current. The On/Off Remote Control interval from inception to VOUT regulated assumes that the converter already has its input voltage stabilized above the Start-Up Threshold before the On command. The interval is measured from the On command until the output enters and remains within its specified regulation band. The specification assumes that the output is fully loaded at maximum rated current. Input Source Impedance These converters will operate to specifications without external components, assuming that the source voltage has very low impedance and reasonable input voltage regulation. Since real-world voltage sources have finite impedance, performance is improved by adding external filter components. Sometimes only a small ceramic capacitor is sufficient. Since it is difficult to totally characterize all applications, some experimentation may be needed. Note that external input capacitors must accept high speed switching currents. Because of the switching nature of DC/DC converters, the input of these converters must be driven from a source with both low AC impedance and adequate DC input regulation. Performance will degrade with increasing input inductance. Excessive input inductance may inhibit operation. The DC input regulation specifies that the input voltage, once operating, must never degrade below the Shut-Down Threshold under all load conditions. Be sure to use adequate trace sizes and mount components close to the converter. I/O Filtering, Input Ripple Current and Output Noise All models in this converter series are tested and specified for input reflected ripple current and output noise using designated external input/output components, circuits and layout as shown in the figures below. External input capacitors (CIN in the figure) serve primarily as energy storage elements, minimizing line voltage variations caused by transient IR drops in the input conductors. Users should select input capacitors for bulk capacitance (at appropriate frequencies), low ESR and high RMS ripple current ratings. In the figure below, the CBUS and LBUS components simulate a typical DC voltage bus. Your specific system configuration may require additional considerations. Please note that the values of CIN, LBUS and CBUS may vary according to the specific converter model. TO OSCILLOSCOPE CURRENT PROBE LBUS CBUS CIN 1 +INPUT VIN + - + - 2 CIN = 33F, ESR < 700m @ 100kHz CBUS = 220F, ESR < 100m @ 100kHz LBUS = 12H -INPUT Figure 2. Measuring Input Ripple Current In critical applications, output ripple and noise (also referred to as periodic and random deviations or PARD) may be reduced by adding filter elements such as multiple external capacitors. Be sure to calculate component temperature rise from reflected AC current dissipated inside capacitor ESR. In figure 3, the two copper strips simulate real-world printed circuit impedances between the power supply and its load. In order to minimize circuit errors and standardize tests between units, scope measurements should be made using BNC connectors or the probe ground should not exceed one half inch and soldered directly to the fixture. Floating Outputs Since these are isolated DC/DC converters, their outputs are "floating" with respect to their input. The essential feature of such isolation is ideal ZERO CURRENT FLOW between input and output. Real-world converters however do exhibit tiny leakage currents between input and output (see Specifications). These leakages consist of both an AC stray capacitance coupling component www.murata-ps.com 17 Aug 2010 email: sales@murata-ps.com MDC_UEI25-120.A02 Page 8 of 11 UEI25-120 Series Single Output Isolated 25-Watt DC/DC Converters it is quite difficult to insert an anemometer to precisely measure airflow in most applications. Sometimes it is possible to estimate the effective airflow if you thoroughly understand the enclosure geometry, entry/exit orifice areas and the fan flowrate specifications. C2 SCOPE RLOAD COPPER STRIP +OUTPUT C1 CAUTION: If you exceed these Derating guidelines, the converter may have an unplanned Over Temperature shut down. Also, these graphs are all collected near Sea Level altitude. Be sure to reduce the derating for higher altitude. Output Overvoltage Protection (OVP) This converter monitors its output voltage for an over-voltage condition using an on-board electronic comparator. The signal is optically coupled to the primary side PWM controller. If the output exceeds OVP limits, the sensing circuit will power down the unit, and the output voltage will decrease. After a time-out period, the PWM will automatically attempt to restart, causing the output voltage to ramp up to its rated value. It is not necessary to power down and reset the converter for this automatic OVP-recovery restart. If the fault condition persists and the output voltage climbs to excessive levels, the OVP circuitry will initiate another shutdown cycle. This on/off cycling is referred to as "hiccup" mode. Output Fusing The converter is extensively protected against current, voltage and temperature extremes. However, your application circuit may need additional protection. In the extremely unlikely event of output circuit failure, excessive voltage could be applied to your circuit. Consider using an appropriate external protection. Output Current Limiting As soon as the output current increases to approximately its overcurrent limit, the DC/DC converter will enter a current-limiting mode. The output voltage will decrease proportionally with increases in output current, thereby maintaining a somewhat constant power output. This is commonly referred to as power limiting. Current limiting inception is defined as the point at which full power falls below the rated tolerance. See the Performance/Functional Specifications. Note particularly that the output current may briefly rise above its rated value. This enhances reliability and continued operation of your application. If the output current is too high, the converter will enter the short circuit condition. Output Short Circuit Condition When a converter is in current-limit mode, the output voltage will drop as the output current demand increases. If the output voltage drops too low, the magnetically coupled voltage used to develop PWM bias voltage will also 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 appropriate value. If the short-circuit condition persists, another shutdown cycle will initiate. This on/off cycling is called "hiccup mode." The hiccup cycling reduces the average output current, thereby preventing excessive internal temperatures. Trimming the Output Voltage The Trim input to the converter allows the user to adjust the output voltage over the rated trim range (please refer to the Specifications). In the trim equations and circuit diagrams that follow, trim adjustments use a single fixed resistor connected between the Trim input and either Vout pin. Trimming resistors should have a low temperature coefficient (100 ppm/deg.C or less) and be mounted -OUTPUT COPPER STRIP C1 = 0.1F CERAMIC C2 = 10F LOW ES LOAD 2-3 INCHES (51-76mm) FROM MODULE Figure 3. Measuring Output Ripple and Noise (PARD) and a DC leakage resistance. When using the isolation feature, do not allow the isolation voltage to exceed specifications. Otherwise the converter may be damaged. Designers will normally use the negative output (-Output) as the ground return of the load circuit. You can however use the positive output (+Output) as the ground return to effectively reverse the output polarity. Minimum Output Loading Requirements These converters employ a synchronous rectifier design topology. 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 protect against thermal over-stress, 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 the next section 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 acceptable under increasing forced airflow measured in Linear Feet per Minute ("LFM"). Note that these are AVERAGE measurements. The converter will accept brief increases in temperature and/or 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 "natural convection" is defined as very low flow rates which are not using fan-forced airflow. Depending on the application, "natural convection" is usually about 30-65 LFM but is not equal to still air (0 LFM). Murata Power Solutions makes Characterization measurements in a closed cycle wind tunnel with calibrated airflow. We use both thermocouples and an infrared camera system to observe thermal performance. As a practical matter, www.murata-ps.com 17 Aug 2010 email: sales@murata-ps.com MDC_UEI25-120.A02 Page 9 of 11 UEI25-120 Series Single Output Isolated 25-Watt DC/DC Converters close to the converter. Keep leads short. If the trim function is not used, leave the trim unconnected. With no trim, the converter will exhibit its specified output voltage accuracy. There are two CAUTIONs to observe for the Trim input: CAUTION: To avoid unplanned power down cycles, do not exceed EITHER the maximum output voltage OR the maximum output power when setting the trim. If the output voltage is excessive, the OVP circuit may inadvertantly shut down the converter. If the maximum power is exceeded, the converter may enter current limiting. If the power is exceeded for an extended period, the converter may overheat and encounter overtemperature shut down. CAUTION: Be careful of external electrical noise. The Trim input is a senstive input to the converter's feedback control loop. Excessive electrical noise may cause instability or oscillation. Keep external connections short to the Trim input. Use shielding if needed. Trim Equations Trim Up UEI25-120-D48 RTUP () = 25000 VO - 12 - 5110 RTDOWN () = 10000 (Vo-2.5) 12 - VO - 5110 Remote On/Off Control On the input side, a remote On/Off Control can be specified with either positive or negative logic as follows: Positive: Models equipped with Positive Logic are enabled when the On/ Off pin is left open or is pulled high to +15VDC with respect to -VIN. An internal bias current causes the open pin to rise to +VIN. Positive-polarity devices are disabled when the On/Off is grounded or brought to within a low voltage (see Specifications) with respect to -VIN. Negative: Models with negative polarity are on (enabled) when the On/Off is grounded or brought to within a low voltage (see Specifications) with respect to -VIN. The device is off (disabled) when the On/Off is left open or is pulled high to +15VDC Max. with respect to -VIN. Dynamic control of the On/Off function should be able to sink the specified signal current when brought low and withstand specified voltage when brought high. Be aware too that there is a finite time in milliseconds (see Specifications) 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. There are two CAUTIONs for the On/Off Control: CAUTION: While it is possible to control the On/Off with external logic if you carefully observe the voltage levels, the preferred circuit is either an open drain/open collector transistor or a relay (which can thereupon be controlled by logic). The On/Off prefers to be set at approx. +15V (open pin) for the ON state, assuming positive logic. CAUTION: Do not apply voltages to the On/Off pin when there is no input power voltage. Otherwise the converter may be permanently damaged. Where Vo = Desired output voltage. Adjustment accuracy is subject to resistor tolerances and factory-adjusted output accuracy. Mount trim resistor close to converter. Use short leads. -INPUT +OUTPUT -INPUT +OUTPUT ON/OFF CONTROL TRIM RTRIM DOWN LOAD ON/OFF CONTROL TRIM R TRIM UP LOAD +INPUT -OUTPUT +INPUT -OUTPUT Figure 4. Trim adjustments to decrease Output Voltage using a Fixed Resistor Figure 5. Trim adjustments to increase Output Voltage using a Fixed Resistor www.murata-ps.com 17 Aug 2010 email: sales@murata-ps.com MDC_UEI25-120.A02 Page 10 of 11 UEI25-120 Series Single Output Isolated 25-Watt DC/DC Converters On/Off Enable Control Ground Bounce Protection To improve reliability, if you use a small signal transistor or other external circuit to select the Remote On/Off control, make sure to return the LO side directly to the -Vin power input on the DC/DC converter. To avoid ground bounce errors, do not connect the On/Off return to a distant ground plane or current-carrying bus. If necessary, run a separate small return wire directly to the -Vin terminal. There is very little current (typically 1-5 mA) on the On/Off control however, large current changes on a return ground plane or ground bus can accidentally trigger the converter on or off. If possible, mount the On/Off transistor or other control circuit adjacent to the converter. DC/DC Converter +VCC Preferred location of On/Off control adjacent to -Vin terminal + Vin On/Off Enable ON/OFF CONTROL On/Off Control Transistor -Vin return -INPUT Do not connect control transistor through remote power bus Ground plane or power return bus Install separate return wire for On/Off control with remote transistor Figure 6. Driving the On/Off Control Pin (suggested circuit) Figure 7. On/Off Enable Control Ground Bounce Protection Murata Power Solutions, Inc. 11 Cabot Boulevard, Mansfield, MA 02048-1151 U.S.A. ISO 9001 and 14001 REGISTERED Murata Power Solutions, Inc. makes no representation that the use of its products in the circuits described herein, or the use of other technical information contained herein, will not infringe upon existing or future patent rights. The descriptions contained herein do not imply the granting of licenses to make, use, or sell equipment constructed in accordance therewith. Specifications are subject to change without notice. (c) 2010 Murata Power Solutions, Inc. www.murata-ps.com/locations 17 Aug 2010 email: sales@murata-ps.com MDC_UEI25-120.A02 Page 11 of 11 |
Price & Availability of UEI25-120
 |
|
|
|
|
All Rights Reserved © IC-ON-LINE 2003 - 2022 |
| [Add Bookmark] [Contact Us] [Link exchange] [Privacy policy] |
|
Mirror Sites : [www.datasheet.hk]
[www.maxim4u.com] [www.ic-on-line.cn]
[www.ic-on-line.com] [www.ic-on-line.net]
[www.alldatasheet.com.cn]
[www.gdcy.com]
[www.gdcy.net] |