40IMX35D12D12-8G

IMX35 Series 35 Watt Quad-Output DC-DC Converter Features 63.5 2.5" 76.2 3" 10.5 0.41" • Extremely wide input voltage ranges up to 150 VDC • 4 outputs up to 60 V • RoHS lead-free-solder and lead-solder-exempted products available • 5 year warranty for RoHS lead-free-solder products • 1500 to 1800 VAC i/o electric strength test • Electrical isolation between outputs • Programmable input undervoltage lockout • Shutdown/inhibit input • Adjustable output voltages with flexible load distribution • Frequency synchronization • Outputs no-load, overload, and short-circuit proof • Operating ambient temperature from –40 to 85 °C • Thermal protection • Low profile: 10.5 mm or 8.9 mm with open frame • Basic insulation • Flexible output possibilities between 5 V and 60 V • Safety-approved to the latest edition of IEC/EN 62368-1, UL/CSA 60950-1 1 1 47.8 1.88" 72.8 2.87" 8.9 0.35" 70/110IMX35 models Table of Contents Description............................................................................2 Model Selection.....................................................................2 Functional Description...........................................................3 Electrical Input Data..............................................................4 Electrical Output Data...........................................................6 Auxiliary Functions..............................................................10 Electromagnetic Compatibility (EMC)..................................12 Immunity to Environmental Conditions................................13 Mechanical Data..................................................................14 Safety and Installation Instructions......................................14 Description of Options.........................................................16 belfuse.com/power-solutions BCD20009-G Rev G, 11 Nov. 2021 IMX35 Series 35 Watt Quad-Output DC-DC Converter Description The IMX35 Series of board-mountable, 35 Watt DC-DC con­verters has been designed according to the latest industry requirements and standards. The converters are particularly suitable for use in mobile or stationary applications in transport, railways, industry, or telecommunication, where variable input voltages or high transient voltages are prevalent. Covering a total input voltage range from 9 V up to 150 V with 4 different models, the converters are available with up to four electrically isolated outputs from 5 V to 60 V, externally adjustable and with flexible load distribution. A shutdown input allows remote converter on/off. Features include consistently high efficiency over the entire input voltage range, high reliability, and excellent dynamic response to load and line changes. The converters are designed and built according to the inter­national safety standards IEC/EN 62368-1 3rd edition, and ap­proved by Nemko. The converters provide basic insulation. The circuit is comprised of 2 planar magnetics devices, and all components are automatically assembled and securely sol­dered onto a single PCB board without any wire connection. Magnetic feedback ensures maximum reliability and re­peatability in the control loop over all operating conditions. Careful consi­derations of possible thermal stresses ensure the absence of hot spots providing long life in environments, where temperature cycles are present. The thermal design without using any potting material allows operation at full load up to an ambient temperature of 71 °C in free air and operation up to 105 °C with airflow. For extremely high vibration environments the case has holes for screw mounting. Model Selection Table 1: Model Selection Output 1 Output 2 Output 3 Output 4 Input voltage Efficiency 1 Model Vo nom [VDC] Io nom [mA] Vo nom [VDC] Io nom [mA] Vo nom [VDC] Io nom [mA] Vo nom [VDC] Io nom [mA] Vi min to Vi max [VDC] η min [%] η max [%] 5 5 5 5 1.35 1.4 1.4 1.4 5 5 5 5 1.35 1.4 1.4 1.4 5 5 5 5 1.35 1.4 1.4 1.4 5 5 5 5 1.35 1.4 1.4 1.4 9 to 36 18 to75 40 to 121 60 to 150 2 82.5 82 83 82 84.5 84 85 84 20IMX35D05D05-8G 40IMX35D05D05-8G 70IMX35D05D05-8G 110IMX35D05D05-8G 12 12 12 12 0.65 0.7 0.7 0.7 12 12 12 12 0.65 0.7 0.7 0.7 12 12 12 12 0.65 0.7 0.7 0.7 12 12 12 12 0.65 0.7 0.7 0.7 9 to 36 18 to75 40 to 121 60 to 150 2 83.5 83.5 84.5 84 85.5 85.5 86.5 86 20IMX35D12D12-8G 40IMX35D12D12-8G 70IMX35D12D12-8G 110IMX35D12D12-8G 15 15 15 15 0.55 0.6 0.6 0.6 15 15 15 15 0.55 0.6 0.6 0.6 15 15 15 15 0.55 0.6 0.6 0.6 15 15 15 15 0.55 0.6 0.6 0.6 9 to 36 18 to75 40 to 121 60 to 150 2 84 83.5 84 83 86 85.5 86 85 20IMX35D15D15-8G 40IMX35D15D15-8G 70IMX35D15D15-8G 110IMX35D15D15-8G 5 5 5 5 1.35 1.4 1.4 1.4 12 12 12 12 0.65 0.7 0.7 0.7 12 12 12 12 0.65 0.7 0.7 0.7 5 5 5 5 1.35 1.4 1.4 1.4 9 to 36 18 to75 40 to 121 60 to 150 2 84 84 84 83.5 86 86 86 85.5 20IMX35D05D12-8G 40IMX35D05D12-8G 70IMX35D05D12-8G 110IMX35D05D12-8G 5 5 5 5 1.35 1.4 1.4 1.4 15 15 15 15 0.55 0.6 0.6 0.6 15 15 15 15 0.55 0.6 0.6 0.6 5 5 5 5 1.35 1.4 1.4 1.4 9 to 36 18 to75 40 to 121 60 to 150 2 83.5 83.5 84 84 85.5 85.5 86 86 20IMX35D05D15-8G 40IMX35D05D15-8G 70IMX35D05D15-8G 110IMX35D05D15-8G Options 2 i, Z, non-G Efficiency at TA = 25 °C, Vo nom, Io nom 154 V for 2 s. 1 2 Product Marking Converters without option Z are marked with type designation, input and output voltages and currents, applicable safety approval and recognition marks, company logo, production date, and serial no. tech.support@psbel.com belfuse.com/power-solutions BCD20009-G Rev G, 11 Nov. 2021 © 2021 Bel Power Solutions & Protection Page 2 of 16 IMX35 Series 35 Watt Quad-Output DC-DC Converter Part Number Description 40 IMX35 - D05 D05 -8 i Z G Input voltage range Vi 9 to 36 VDC............................................. 20 18 to 75 VDC............................................. 40 40 to 121 VDC............................................. 70 60 to 150 VDC............................................110 Series........................................................................ IMX35 Outputs 1 and 4 (1st power train)..................D05, D12, D15 Outputs 2 and 3 (2nd power train).................D05, D12, D15 Operating ambient temperature range TA = – 40 to 85 °C ......................................- 8 Options: Inhibit.............................................................-i Open frame................................................... Z RoHS compliant for all six substances........ G Note: The sequence of options must follow the order above ! NFND: Not for new designs. Preferred for new designs. Functional Description The IMX35 converters are comprised of 2 feedback-controlled interleaved-switching flyback powertrains using current mode control. Each converter consists of 4 electrically isolated outputs deriving from the 2 power trains. Vo1, Vo4 derive from the first powertrain and Vo2, Vo3 from the second one. Thus each pair of outputs is independent from the other one. Voltage regulation for each pair of outputs is achieved with passive transformer feedback from the main trans­former of the powertrain. Each pair of outputs has the same output voltage (i.e. D05, D12, etc.). If both powertrains have the same nominal output voltage (e.g. D12D12), all outputs may be simul­taneously adjusted by the Trim input (pin 5). In case of different output voltages (e.g. D05D15), the Trim1 input influences only Vo1 and Vo4. Current limitation is provided on the primary side for each powertrain and limits the possible output power for each pair of outputs. In the case of an overload on either of the power trains, which causes the output voltage to fall to less than typically 70% of Vo nom, the entire converter shuts down and auto­matically restart in short intervals (hiccup mode). The incorporated overtemperature protection shuts down the hole converter in the case of overtemperature and resumes automatically after cooling down. 03098b Vi+ 4 16 Vo1+ PUL 1 15 Vo1– Trim/Trim1 5 W 6 PWM 17 Vo4+ Ref 7 SD 8 18 Vo4– Vi– 2 n.c. 3 13 Vo2+ 14 Vo2– 12 Vo3+ 11 Vo3– 19 n.c. Fig. 1 Block diagram of quad-output models tech.support@psbel.com belfuse.com/power-solutions BCD20009-G Rev G, 11 Nov. 2021 © 2021 Bel Power Solutions & Protection Page 3 of 16 IMX35 Series 35 Watt Quad-Output DC-DC Converter Electrical Input Data General conditions: TA = 25 °C, unless specified Pins 8 (shutdown or i), 6 (W), 5 (Trim or Trim1), and 1 (PUL) left open-circuit (not connected), unless specified. Table 2: Input Data Model 20IMX35 Characteristics Conditions min Vi Input voltage range Vi nom Nominal input voltage Io = 0 to Io nom Vi sur Repetitive surge voltage Abs. max input (3 s) 1 Switch on TA min to TA max, 9 typ 2 40IMX35 max min 36 18 typ 40 40 0.25 V 100 0.5 0.25 0.5 tstart-up Converter start-up time 2 trise Rise time 3 Ii o No-load input current Io = 0, Vi min to Vi max 70 50 mA Ii rr Reflected ripple current Io = 0 to I o nom 30 30 mApp Ii inr p Inrush peak current 4 Vi = Vi nom 8 9 A Ci Input capacitance For surge calculation SD high Worst case condition at Vi min, and full load max 75 2 20 Unit 0.1 Vi nom, resistive load 3 I o nom, capacitive load 6 3 12 6 2 1.3 -10 to +0.7 -10 to +0.7 Converter operating open circuit or 2 to 20 open circuit or 2 to 20 approx. 10 approx. 10 Shutdown voltage RSD Shutdown input resistance ISD Input current during shutdown Vi min to Vi max fs Switching frequency Vi min to Vi max, Io = 0 to I o nom 12 220 Model 240 220 70IMX35 Characteristics Conditions min 40 2 typ ms 12 Converter disabled VSD s 0.1 µF V kΩ 6 mA 240 kHz 110IMX35 max min 121 60 2 typ Unit max Vi Input voltage range 1 TA min to TA max, Vi nom Nominal input voltage Io = 0 to Io nom Vi sur Repetitive surge voltage Abs. max input (3 s) tstart-up Converter start-up time 2 trise Rise time 3 Ii o No-load input current Io = 0, Vi min to Vi max 30 20 mA Ii rr Reflected ripple current Io = 0 to I o nom 30 30 mApp Ii inr p Inrush peak current 4 Vi = Vi nom Ci Input capacitance For surge calculation VSD Shutdown voltage RSD Shutdown input resistance ISD Input current during shutdown Vi min to Vi max fs Switching frequency Vi min to Vi max, Io = 0 to I o nom Switch on SD high 70 Worst case condition at Vi min, and full load 150 5 110 150 0.25 0.5 0.4 0.1 Vi nom, resistive load 3 I o nom, capacitive load 6 V 170 0.7 3 12 6 7 ms 12 7 0.5 A 0.5 µF Converter disabled -10 to +0.7 -10 to +0.7 Converter operating open circuit or 2 to 20 open circuit or 2 to 20 approx. 10 approx. 10 220 s 0.1 V kΩ 5 5 mA 240 225 6 kHz Vi min will not be as stated, if Vo is increased above Vo nom by use of Trim input. If the output voltage is set to a higher value, Vi min will be proportionately increased. 2 Input undervoltage lockout at typ. 85% of Vi min. 3 Measured with resistive and max. admissible capacitive load. 4 Source impedance according to ETS 300132-2, version 4.3. 5 154 V during 2 s 6 Revision BA or later. Older converters had fs ≤ 240 kHz. 1 tech.support@psbel.com belfuse.com/power-solutions BCD20009-G Rev G, 11 Nov. 2021 © 2021 Bel Power Solutions & Protection Page 4 of 16 IMX35 Series 35 Watt Quad-Output DC-DC Converter Inrush Current The inrush current has been made as low as possible by choosing a very small input capacitance. A series resistor may be installed in the input line to further reduce this current. A Vo 04022b 4 trise Vo nom 3 04008b 2 1 0 20 60 40 80 t 100 µs Fig. 2 Typical inrush current at Vi nom, Po nom versus time (40IMX35). Source impedance according to ETS 300132-2 at Vi nom. t tstartup Fig. 3 Converter start-up and rise time (see table 2) Reverse Polarity Protection The built-in suppressor diode also provides for reverse polarity protection at the input by conducting current in the reverse direction. An external fuse is required to limit this current. Table 3: Recommended external fuses in the non-earthed input line Model Fuse type 20IMX35 F 8.0 A 40IMX35 F 4.0 A 70IMX35 F 2.0 A 110IMX35 F 1.5 A Input Transient Voltage Protection A built-in suppressor diode provides effective protection against input transients, which may be generated for example by shortcircuits across the input lines, where the network inductance may cause high energy pulses. Table 4: Built-in transient voltage suppressor Model Breakdown voltage VBR nom [V] Peak power at 1 ms P P [Ω] Peak pulse current IPP [A] 20IMX35 39 1500 22 40IMX35 100 1500 9.7 70IMX35 151 600 2.9 110IMX35 176 600 2.5 For very high energy transients as for example to achieve IEC/EN 61000-4-5 compliance (as per table Electro­magnetic Immunity) an external inductor and capacitor are required. The components should have similar characteristics as listed in table below. Table 5: Components for external circuitry for IEC/EN 61000-4-5, level 2 Model Inductor (L) Capacitor (C1 , C2) Diode (D) 20IMX35 1.45 mH / 5 A C1, C2: 220 μF / 50 V 1.5 k E47A 40IMX35 4 mH / 3 A C1, C2: 100 μF / 100 V --- 70IMX35 4 mH / 1.5 A C1: 120 μF / 160 V C2: 240 μF / 160 V --- 110IMX35 4.5 mH / 1.5 A C1: 120 μF / 200 V C2: 240 μF / 200 V --- Vi+ L C1 + C2 + D IMX35 Vi– Fig. 4 Example for external circuitry to comply with IEC/EN 61000-4-5; the diode D is only necessary for 20IMX35 models. tech.support@psbel.com belfuse.com/power-solutions BCD20009-G Rev G, 11 Nov. 2021 © 2021 Bel Power Solutions & Protection Page 5 of 16 IMX35 Series 35 Watt Quad-Output DC-DC Converter Electrical Out put Data We recommend connecting an external 1 µF ceramic capacitor across the output pins. General conditions: – TA = 25 °C, unless TC is specified – Pins 8 (shutdown or i), 6 (W), 5 (Trim or Trim1), and 1 (PUL) left open-circuit (not connected), unless specified. Table 6: Output data per double-output powertrain (Vo1/Vo4 or Vo2/Vo3; each power train has 2 outputs) Output 2x5V Characteristics V o1 V o2 Io nom Output voltage Output current Conditions min Vi nom, I o = 0.5 I o nom 4.95 4.94 max min typ 5.05 5.06 11.88 11.86 2 x 15 V max min 12.12 12.14 14.85 14.82 typ 2 x 1.35 2 x 0.65 2 x 0.55 40IMX 2 x 1.40 2 x 0.70 2 x 0.60 70IMX Vi min to Vi max 2 x 1.40 2 x 0.70 2 x 0.60 110IMX 2 x 1.40 2 x 0.70 2 x 0.60 20IMX 3.5 1.8 1.5 40IMX Vi nom, TC = 25 °C, 3.8 2.0 1.7 70IMX Vo = 93% Vo nom 3.8 2.0 1.7 Current limit 1 ∆Vo Line regulation Vi min to Vi max , I o nom ∆Vo l Load regulation Vi nom, I o = (0.1 to 1) I o nom 110IMX 3.8 ±3 ±3 120 150 I o = I o nom 3 40 60 70 Min. load 1% Co ext Admissible capacitive load per power train 6 produced after 2011 produced until 2011 αVo Temperature coefficient ∆Vo / ∆TC Recovery time ±1 ±3 Output overvoltage limit 4 Voltage deviation 1.7 ±1 80 Vo L 115 Vi nom, I o nom ↔ 1/2 I o nom Vi min to Vi max , I o = (0.1 to 1) I o nom 0 0 115 6000 4000 115 0 0 V A 2 Output voltage noise 5 Dynamic load regulation max Vi min to Vi max Vo1/2 td 2.0 ±1 Unit 15.15 15.18 20IMX Io L Vo d typ 2 x 12 V 680 470 0 0 % mVpp % 470 330 µF ±250 ±480 ±520 mV 0.75 0.75 0.75 ms ±0.02 ±0.02 ±0.02 %/K Both outputs of each powertrain connected in parallel. The current limit is primary side controlled. In the case of an overload condition, the thermal protection may cause the converter to shut down (automatic restart on cool-down). 2 BW = 20 MHz, measured with an external capacitor of 1 µF across the output pins. 3 Measured with a probe according to EN 61204 4 The output overvoltage protection is located on the primary side. It is not tracking the Trim/Trim1 control. 5 Both outputs of each powertrain connected in parallel. 6 Sum of capacities on the outputs of each powertrain. 1 tech.support@psbel.com belfuse.com/power-solutions BCD20009-G Rev G, 11 Nov. 2021 © 2021 Bel Power Solutions & Protection Page 6 of 16 IMX35 Series 35 Watt Quad-Output DC-DC Converter Thermal Considerations If a converter, mounted on a PCB, is located in free, quasi-stationary air (convection cooling) at the indicated maximum ambient temperature TA max (see table Temperature specifi­cations) and is operated at its nominal input voltage and output power, the case temperature TC (TC Z with option Z) measured at the measuring point of case temperature (see Mechanical Data) will approach the indicated value TC max after the warm-up phase. However, the relationship between TA and TC depends heavily on the conditions of operation and integration into a system. The thermal conditions are influenced by input voltage, output current, airflow, temperature of surrounding components and the surfaces and properties of the printed circuit board. TA max is therefore only an indicative value, and under practical operating conditions, the ambient temperature TA may be higher or lower than this value. Caution: The case temperature TC (or TC Z) measured at the measuring point of case temperature (see Mechanical Data) may under no circumstances exceed the specified maximum value. The installer must ensure that under all operating conditions TC (or TC Z) remains within the limits stated in the table Temperature specifications. The converters provide the specified output power with free air convection cooling. In the upper temperature range the output power derating below should be observed. Po /Po max 11047-X35a 1.0 0.8 0.5 m/s = 100 LFM 0.6 natural cooling 0.4 0.2 0 20 40 60 80 100 °C TA Fig. 5 Maximum allowed output power versus ambient temperature (models with and without option Z) Overtemperature Protection The converter is protected against possible over­heating by means of an internal temperature monitoring circuit located on the primary side. It shuts down the converter above the internal temperature limit and attempts to restart auto­matically. This feature prevents excessive internal temperature building up which could occur under overload conditions. Short Circuit Behavior The current limit characteristic shuts down the converter whenever a short circuit is applied to an output. It acts self-protecting and automatically recovers after removal of the overload condition (hiccup mode). Vo [%] 100 70 0 overload short-circuit condition switch-off 05041b 0.3 s t Fig. 6 Overload switch off (hiccup mode), typical values. tech.support@psbel.com belfuse.com/power-solutions BCD20009-G Rev G, 11 Nov. 2021 © 2021 Bel Power Solutions & Protection Page 7 of 16 IMX35 Series 35 Watt Quad-Output DC-DC Converter Series and Parallel Connection The outputs of one or several double-output powertrains may be connected in series respecting the current limitation. Both outputs of the same powertrain can always be connected in parallel in will behave like a single output. Several outputs of the same converter with equal output voltage (e.g. 5 V / 5 V) can be connected in parallel and will share their output currents almost equally. If outputs of the same converter are being parallel and series-connected, it is recommended that outputs from the same powertrains are parallel-connected first. This applies for instance, if 24 V shall be generated by a converter with four 12 V outputs; see fig. 7. JM138a Vi+ 4 IMX35D12D12 PUL 1 Vo1– 15 Trim 5 W 6 Vo1+ 16 Vo4+ 17 PWM Ref 7 Vo4– –24V Vo2+ +24V 18 SD 8 Vi– 2 13 n.c. 3 14 12 11 Vo2– Vo3+ Vo3– 19 n.c. Fig. 7 Generating 24 V with an IMX35D12D12-8 Note: Parallel operation of several converters may cause start-up problems. This becomes noticeable in applications, where one converter is not able to deliver the full resistive and capacitive load current alone, as it is required in true redundant systems. Typical Performance Curves General conditions: – TA = 25°C, unless TC is specified. – Shut down and Trim pin left open-circuit. Vo [V] Vo4 [V] 05020-X35 13 05164b 13.5 12 13 11 12.5 10 9 12 8 11.5 0 0.5 1 1.5 2 A Io total Fig. 8 Vo versus Io (typ.) of a double-output power train, with both outputs in parallel (e.g., Vo1/4 of a 40IMX35D12D12) Io4 = 0.035 A Io4 = 0.35 A Io1 0.06 0.1 0.2 0.3 0.4 0.5 0.6 0.7 A Fig. 9 Cross load regulation (typ.) on powertrain 1. Vo4 versus Io1 tech.support@psbel.com belfuse.com/power-solutions BCD20009-G Rev G, 11 Nov. 2021 © 2021 Bel Power Solutions & Protection Page 8 of 16 IMX35 Series 35 Watt Quad-Output DC-DC Converter Vo1, Vo4 [V] 05039b 14 13 Vo4 12 Vo1 11 10 0 0.25 0.5 0.75 1 1.25 1.5 Io1/Io1 nom Fig. 10 Flexible load distribution (typ.) on power train 1 of a 40IMX35D12D12-8: Vo1 versus Io1, Io4 = 0.5 Io4 nom η [%] η [%] 90 05153a 90 Vi min 80 Vi nom 80 Vi nom 70 60 25 05152a Vi min 70 50 75 Po 100 % Po total Fig. 11 Efficiency versus input voltage and load. Typical values (20IMX35D12D12-8) 60 25 50 75 Po 100 % Po total Fig. 12 Efficiency versus input voltage and load. Typical values (40IMX35D12D12-8) tech.support@psbel.com belfuse.com/power-solutions BCD20009-G Rev G, 11 Nov. 2021 © 2021 Bel Power Solutions & Protection Page 9 of 16 IMX35 Series 35 Watt Quad-Output DC-DC Converter Auxiliary Functions Adjustable Output Voltage As a standard feature, the IMX35 offer adjustable output voltages in the range of 85 to 105% of Vo nom. Fig. 13 shows the schematic diagram for the adjustment of quad-output models. All models with equal output voltages have a Trim input at pin 5 referenced to the primary side, influencing all outputs simultaneously. Models with different output voltages exhibit a Trim1 input, influencing only the first power train (Vo1 and Vo4). Adjustment by means of an external resistor Rext: 06137c Vi+ Trim + – Vext 4 16 5 15 Control circuit Vref = 2.5 V Rext Vi– 2 13 14 Vo1+ Vo1– Vo2+ Vo2– Fig. 13 Output voltage control by means of the Trim input Table 7: Rext for Vo > Vo nom; approximate values (Vi nom, Io = 0.5 Io nom) Vo [%Vo nom] 105 to 108 (107 typically) 105 102 100 Table 8: Vo versus Vext for Vo = 85 to 105% Vo nom; typical values (Vi nom, Io = 0.5 Io nom) Rext [kΩ] Trim Trim 1 0 10 62 ∞ 0 17 110 ∞ Vo [%Vo nom] Vext [V] > 105 102 100 95 90 85 Trim [V] Trim 1 [V] 0 1.8 2.5 4.3 6.2 8 0 1.5 2.5 4.25 6.2 8 Adjustment of the output voltage by means of an external resistor Rext is possible within the range of 100 to 105% of Vo nom. Rext should be connected between Trim (pin 5) and Vi– (pin 2). The following table indicates suitable resistor values for typical output voltages under nominal conditions (Vi nom, Io = 0.5 Io nom). Note: Connection of Rext to Vi+ may damage the converter. Adjustment by means of an external voltage source Vext For external output voltage adjustment in the range 85 to 105% of Vo nom a voltage source Vext (0 to 20 V) is required, connected to Trim or Trim1 (pin 5) and Vi–. The table below indicates typical values Vo versus Vext. Applying a control voltage of 15 to 20 V will set the converter into the hiccup mode. Direct paralleling of the Trim pins of converters of the same type connected in parallel is feasible. Synchronization (W) It is possible to synchronize the switching frequency of one or more converters to an external clock signal. This logic input W can be used to synchronize the oscillator to an external frequency source. This signal is edge-triggered with TTL thresholds and requires a source frequency of 440 to 480 kHz (duty cycle 10 to 90%). The external source frequency is internally divided by 2 to define the switching frequency of the converter. If unused, this pin can be connected to V1– (pin 2) or left open-circuit. Reference Output (Ref) The converter provides a stable 5 V (±0.1 V) reference signal on pin 7 (Ref). The output is protected by a 1 kΩ resistor. The signal may be used also in conjunction with the Trim input (pin 5) as a limited external voltage reference. It is recommended to connect a filter capacitor (0 .1 µF) between Ref and Vi–, if Ref is used. tech.support@psbel.com belfuse.com/power-solutions BCD20009-G Rev G, 11 Nov. 2021 © 2021 Bel Power Solutions & Protection Page 10 of 16 IMX35 Series 35 Watt Quad-Output DC-DC Converter Shutdown The outputs of the converters may be enabled or disabled by means of a logic signal (TTL, CMOS, etc.) applied to shut­down (pin 8). If the shutdown function is not required, pin 8 should be left open-circuit: Converter operating: Converter disabled: 2.0 to 20 V –10 to +0 .7 V Progr. Input Undervoltage Lockout PUL A special feature of the converter (with Rev. BA or later) is the adjustable undervoltage lockout protection, which protects the converter (and the system) from high current caused by operation at low input voltages. This ensures easier start-up in distributed power systems. The table below shows the band of switch on/off and the hysteresis. Table 9: Trigger level and hysteresis (pin 1 left open) Model Trigger level Hysteresis 20IMX35 7 to 8