B59755B0115A070

## **PTC thermistors as inrush current limiters** 

Leaded disks, uncoated 

**Series/Type: B5975*/ B5977*** Date: April 2014 

© EPCOS AG 2014. Reproduction, publication and dissemination of this publication, enclosures hereto and the information contained therein without EPCOS' prior express consent is prohibited. 

## **Inrush current limiters** ~~ee~~ **Leaded disks, uncoated** 

## **Applications** 

- Inrush current limiter (charging resistor) for smoothing and DC link capacitors To replace high-power fixed resistors for capacitor charging 

- | 

- **Features** Self-protecting in case of malfunction of 

- a short-circuit relay or internal short circuit of capacitor 

## **Dimensional drawing** 

- Inrush current limiters are not damaged when directly connected to Vmax even without additional current limitation 

- Marking: Type, manufacturer's logo, reference temperature in ° C and date code YYWW 

- UL approval to UL 1434 with Vmax = 420 V 

- and VR = 380 V (file number E69802) 

- VDE approval for selected types 

- (licence number 104843 E) RoHS-compatible 

## **Delivery mode** 

- Cardboard strips 

## **Dimensions in mm** 

|Type|wmax<br>h|hmax|thmax|
|---|---|---|---|
|B750<br>B751<br>B752<br>B753<br>B754<br>B755<br>B770<br>B771<br>B772<br>B773|12.5<br>16.5<br>12.5<br>16.5<br>12.5<br>16.5<br>12.5<br>16.5<br>12.5<br>16.5<br>12.5<br>16.5<br>8.5<br>12.0<br>8.5<br>12.0<br>8.5<br>12.0<br>8.5<br>12.0|16.5<br>16.5<br>16.5<br>16.5<br>16.5<br>16.5<br>12.0<br>12.0<br>12.0<br>12.0|5.0<br>7.0<br>7.0<br>7.0<br>7.0<br>7.0<br>7.0<br>7.0<br>7.0<br>7.0|



## **General technical data** 

|Operating cycles at Vmax<br>(charging of capacitor)<br>Switching cycles at Vmax<br>(failure mode)<br>Operating temperature range<br>(V = 0)<br>Operatingtemperature range<br>(V = Vmax)|Nc<br>Nf<br>Top<br>Top|> 50000<br>> 10<br>40/+125<br>20/+85|cycles<br>cycles<br>°C<br>°C|
|---|---|---|---|



## **Electrical specifications and ordering codes** 

|Type|Vmax<br>V AC<br>~~PT~~|Vlink,max<br>V DC<br>~~PTLTE~~|RR<br>Ω<br>~~LTE~~|∆RR<br>%<br>~~LTE~~|Tref<br>(typ.)<br>°C<br>~~LTE~~<br>~~LT~~|Cth<br>J/K<br>~~LTE~~<br>~~LT~~|τth<br>s<br>~~LTE~~<br>~~LTdw~~|Approvals<br>Ordering code<br>~~LTE~~<br>~~dw~~|Ordering code|
|---|---|---|---|---|---|---|---|---|---|
|B750<br>B751<br>B752<br>B753<br>B754<br>B755|260<br>260<br>260<br>440<br>440<br>560<br>~~PT~~|360<br>360<br>360<br>620<br>620<br>800<br>~~PTLTE~~|25<br>50<br>80<br>120<br>150<br>500<br>~~LTE~~|±25<br>±25<br>±25<br>±25<br>±25<br>±25<br>~~LTE~~|115<br>115<br>115<br>115<br>115<br>110<br>~~LTE~~<br>~~LT~~|1.0<br>1.4<br>1.4<br>1.4<br>1.4<br>1.4<br>~~LTE~~<br>~~LT~~|100<br>120<br>120<br>120<br>120<br>120<br>~~LTE~~<br>~~LT dw~~|X<br>X<br>B59750B0120A070<br>X<br>X<br>B59751B0120A070<br>X<br>X<br>B59752B0120A070<br>X<br>X<br>B59753B0120A070<br>X<br>X<br>B59754B0120A070<br>X<br>X<br>B59755B0115A070<br>~~LTE~~<br>~~dw~~|B59750B0120A070<br>B59751B0120A070<br>B59752B0120A070<br>B59753B0120A070<br>B59754B0120A070<br>B59755B0115A070|



Please read _Cautions and warnings_ and _Important notes_ at the end of this document. 

Page 2 of 12 

## **Inrush current limiters** ~~Lt~~ **Leaded disks, uncoated** 

|Vmax<br>V AC<br>Seeeeee|Vlink,max<br>V DC<br>Seeeeee|RR<br>Ω<br>Seeeeee|∆RR<br>%<br>Seeeeee|Tref<br>(typ.)<br>°C<br>Seeeeee|Cth<br>J/K<br>Seeeeee|τth<br>s<br>Seeeeee|Approvals<br>Seeeeee~~e~~|
|---|---|---|---|---|---|---|---|
|260<br>260<br>260<br>440<br>Seeeeee|360<br>360<br>360<br>620<br>Seeeeee|70<br>120<br>150<br>500<br>Seeeeee|±25<br>±25<br>±25<br>±25<br>Seeeeee|120<br>120<br>120<br>120<br>Seeeeee|0.4<br>0.6<br>0.6<br>0.6<br>Seeeeee|70<br>80<br>80<br>80<br>Seeeeee|X<br>X<br>X<br>X<br>X<br>X<br>X<br>X<br>Seeeeee~~e~~|



Please read _Cautions and warnings_ and _Important notes_ at the end of this document. 

Page 3 of 12 

|**Reliability data**<br>Test<br>Standard<br>Test conditions<br>∆R25/R25<br>Electrical endurance,<br>cycling<br>Room temperature, Vlink,max<br>applied energy < Cth<br>(Tref<br>TA)<br>Number of cycles: 100 000<br>< 25%<br>Electrical endurance,<br>constant<br>IEC 60738-1<br>Storage at Vmax/Top,max(Vmax)<br>Test duration: 1000 h<br>< 25%<br>Damp heat<br>IEC 60738-1<br>Temperature of air: 40°C<br>Relative humidity of air: 93%<br>Duration: 56 days<br>Test accordingto IEC 60068-2-78<br>< 10%<br>Rapid change<br>of temperature<br>IEC 60738-1<br>T1= Top,min(0 V), T2= Top,max(0 V)<br>Number of cycles: 5<br>Test duration: 30 min<br>Test accordingto IEC 60068-2-14, test Na<br>< 10%<br>Vibration<br>IEC 60738-1<br>Frequency range: 10 to 55 Hz<br>Displacement amplitude: 0.75 mm<br>Test duration: 3×2 h<br>Test accordingto IEC 60068-2-6, test Fc<br>< 5%<br>Climatic sequence<br>IEC 60738-1<br>Dry heat: T = Top,max(0 V)<br>Test duration: 16 h<br>Damp heat first cycle<br>Cold: T = Top,min(0 V)<br>Test duration: 2 h<br>Damp heat 5 cycles<br>Tests performed according to<br>IEC 60068-2-30<br>< 10%<br>**Inrush current limiters**<br>**Leaded disks, uncoated**<br>~~Lt=~~|**Reliability data**<br>Test<br>Standard<br>Test conditions<br>∆R25/R25<br>Electrical endurance,<br>cycling<br>Room temperature, Vlink,max<br>applied energy < Cth<br>(Tref<br>TA)<br>Number of cycles: 100 000<br>< 25%<br>Electrical endurance,<br>constant<br>IEC 60738-1<br>Storage at Vmax/Top,max(Vmax)<br>Test duration: 1000 h<br>< 25%<br>Damp heat<br>IEC 60738-1<br>Temperature of air: 40°C<br>Relative humidity of air: 93%<br>Duration: 56 days<br>Test accordingto IEC 60068-2-78<br>< 10%<br>Rapid change<br>of temperature<br>IEC 60738-1<br>T1= Top,min(0 V), T2= Top,max(0 V)<br>Number of cycles: 5<br>Test duration: 30 min<br>Test accordingto IEC 60068-2-14, test Na<br>< 10%<br>Vibration<br>IEC 60738-1<br>Frequency range: 10 to 55 Hz<br>Displacement amplitude: 0.75 mm<br>Test duration: 3×2 h<br>Test accordingto IEC 60068-2-6, test Fc<br>< 5%<br>Climatic sequence<br>IEC 60738-1<br>Dry heat: T = Top,max(0 V)<br>Test duration: 16 h<br>Damp heat first cycle<br>Cold: T = Top,min(0 V)<br>Test duration: 2 h<br>Damp heat 5 cycles<br>Tests performed according to<br>IEC 60068-2-30<br>< 10%<br>**Inrush current limiters**<br>**Leaded disks, uncoated**<br>~~Lt=~~|**Reliability data**<br>Test<br>Standard<br>Test conditions<br>∆R25/R25<br>Electrical endurance,<br>cycling<br>Room temperature, Vlink,max<br>applied energy < Cth<br>(Tref<br>TA)<br>Number of cycles: 100 000<br>< 25%<br>Electrical endurance,<br>constant<br>IEC 60738-1<br>Storage at Vmax/Top,max(Vmax)<br>Test duration: 1000 h<br>< 25%<br>Damp heat<br>IEC 60738-1<br>Temperature of air: 40°C<br>Relative humidity of air: 93%<br>Duration: 56 days<br>Test accordingto IEC 60068-2-78<br>< 10%<br>Rapid change<br>of temperature<br>IEC 60738-1<br>T1= Top,min(0 V), T2= Top,max(0 V)<br>Number of cycles: 5<br>Test duration: 30 min<br>Test accordingto IEC 60068-2-14, test Na<br>< 10%<br>Vibration<br>IEC 60738-1<br>Frequency range: 10 to 55 Hz<br>Displacement amplitude: 0.75 mm<br>Test duration: 3×2 h<br>Test accordingto IEC 60068-2-6, test Fc<br>< 5%<br>Climatic sequence<br>IEC 60738-1<br>Dry heat: T = Top,max(0 V)<br>Test duration: 16 h<br>Damp heat first cycle<br>Cold: T = Top,min(0 V)<br>Test duration: 2 h<br>Damp heat 5 cycles<br>Tests performed according to<br>IEC 60068-2-30<br>< 10%<br>**Inrush current limiters**<br>**Leaded disks, uncoated**<br>~~Lt=~~|
|---|---|---|
|Please read_Cautions and warnings_and|Page 4 of 12||
|_Important notes_at the end of this document.|||



## **Inrush current limiters** 

## **Leaded disks, uncoated** 

## **Characteristics** 

Minimum resistance of PTC thermistors versus applied voltage (pulsed) 

Switching time tS versus switching current IS (measured at 25 ° C in still air) 

PTC resistance RPTC versus PTC temperature TPTC (measured at low signal voltage) 

Residual current in high-ohmic state Ires as function of applied voltage VPTC, typical (measured at 25 ° C in still air) 

Please read _Cautions and warnings_ and _Important notes_ at the end of this document. 

Page 5 of 12 

## **Inrush current limiters** 

## **Leaded disks, uncoated** 

## **Characteristics** 

Minimum resistance of PTC thermistors versus applied voltage (pulsed) 

Switching time tS versus switching current IS (measured at 25 ° C in still air) 

PTC resistance RPTC versus PTC temperature TPTC (measured at low signal voltage) 

Residual current in high-ohmic state Ires as function of applied voltage VPTC, typical (measured at 25 ° C in still air) 

Please read _Cautions and warnings_ and _Important notes_ at the end of this document. 

Page 6 of 12 

## **Inrush current limiters** ~~ee~~ **Leaded disks, uncoated** 

## **Calculation of the number of required PTC elements** 

Number of required PTC elements (connected in parallel) as function of capacitance and charging voltage of smoothing or DC link capacitor: 

|N= 2:|.<br>2<br> Ctr~~ESS~~ Tamax)|
|---|---|
|N|Number of required PTC thermistors connected inparallel|
|C|Capacitance of smoothingor DC link capacitor in F|
|V|Chargingvoltage of capacitor in V|
|Cth|Heat capacityin J/K|
|Tref|Reference temperature of PTC in°C|
|TA,max|Expected maximum ambient temperature in°C|



In case of large N values the resulting resistance of the parallel PTC network might be too low for effective limitation of the charging current. In this case a combination of series and parallel connected PTC thermistors can be used. 

Please read _Cautions and warnings_ and _Important notes_ at the end of this document. 

Page 7 of 12 

**Inrush current limiters** ~~Lt~~ **Leaded disks, uncoated** 

## **Cautions and warnings** 

## **General** 

- EPCOS thermistors are designed for specific applications and should not be used for purposes not identified in our specifications, application notes and data books unless otherwise agreed with EPCOS during the design-in-phase. 

- Ensure suitability of thermistor through reliability testing during the design-in phase. The thermistors should be evaluated taking into consideration worst-case conditions. 

## **Storage** 

- Store thermistors only in original packaging. Do not open the package before storage. Storage conditions in original packaging: storage temperature 25 ° C ... +45 ° C, relative humidity ≤ 75% annual mean, maximum 95%, dew precipitation is inadmissible. 

- Avoid contamination of thermistors surface during storage, handling and processing. 

- Avoid storage of thermistor in harmful environment with effect on function on long-term operation (examples given under operation precautions). 

Use thermistor within the following period after delivery: 

Through-hole devices (housed and leaded PTCs): 24 months 

Motor protection sensors, glass-encapsulated sensors and probe assemblies: 24 months Telecom pair and quattro protectors (TPP, TQP): 24 months Leadless PTC thermistors for pressure contacting: 12 months Leadless PTC thermistors for soldering: 6 months 

- SMDs in EIA sizes 3225 and 4032, and for PTCs with metal tags: 24 months SMDs in EIA sizes 0402, 0603, 0805 and 1210: 12 months 

## **Handling** 

PTCs must not be dropped. Chip-offs must not be caused during handling of PTCs. Components must not be touched with bare hands. Gloves are recommended. Avoid contamination of thermistor surface during handling. 

## **Soldering (where applicable)** 

Use rosin-type flux or non-activated flux. 

Insufficient preheating may cause ceramic cracks. 

- Rapid cooling by dipping in solvent is not recommended. Complete removal of flux is recommended. 

Standard PTC heaters are not suitable for soldering. 

Please read _Cautions and warnings_ and _Important notes_ at the end of this document. 

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## **Inrush current limiters** ~~Lt~~ **Leaded disks, uncoated** 

## **Mounting** 

- Electrode must not be scratched before/during/after the mounting process. 

- Contacts and housing used for assembly with thermistor have to be clean before mounting. Especially grease or oil must be removed. 

- When PTC thermistors are encapsulated with sealing material, the precautions given in chapter "Mounting instructions", "Sealing and potting" must be observed. 

- When the thermistor is mounted, there must not be any foreign body between the electrode of the thermistor and the clamping contact. 

- The minimum force of the clamping contacts pressing against the PTC must be 10 N. 

- During operation, the thermistor’s surface temperature can be very high. Ensure that adjacent components are placed at a sufficient distance from the thermistor to allow for proper cooling at the thermistors. 

- Ensure that adjacent materials are designed for operation at temperatures comparable to the surface temperature of thermistor. Be sure that surrounding parts and materials can withstand this temperature. 

Avoid contamination of thermistor surface during processing. 

## **Operation** 

Use thermistors only within the specified temperature operating range. 

- Use thermistors only within the specified voltage and current ranges. 

- Environmental conditions must not harm the thermistors. Use thermistors only in normal atmospheric conditions. Avoid use in deoxidizing gases (chlorine gas, hydrogen sulfide gas, ammonia gas, sulfuric acid gas etc), corrosive agents, humid or salty conditions. Contact with any liquids and solvents should be prevented. 

- Be sure to provide an appropriate fail-safe function to prevent secondary product damage caused by abnormal function (e.g. use VDR for limitation of overvoltage condition). 

This listing does not claim to be complete, but merely reflects the experience of EPCOS AG. 

Please read _Cautions and warnings_ and _Important notes_ at the end of this document. 

Page 9 of 12 

## **Inrush current limiters** ~~Lt~~ **Leaded disks, uncoated** 

## **Symbols and terms** 

|Symbol|Term|
|---|---|
|A<br>C<br>Cth<br>f<br>I<br>Imax<br>IR<br>Ires<br>IPTC<br>Ir<br>Ir,oil<br>Ir,air<br>IRMS<br>IS<br>ISmax<br>LCT<br>N<br>Nc<br>Nf<br>P<br>P25<br>Pel<br>Pdiss<br>RG<br>Rmin<br>RR<br>∆RR<br>RP<br>RPTC<br>Rref<br>RS<br>R25<br>R25,match<br>∆R25<br>T<br>t<br>TA|Area<br>Capacitance<br>Heat capacity<br>Frequency<br>Current<br>Maximum current<br>Rated current<br>Residual current<br>PTC current<br>Residual currrent<br>Residual currrent in oil (for level sensors)<br>Residual currrent in air (for level sensors)<br>Root-mean-square value of current<br>Switching current<br>Maximum switching current<br>Lower category temperature<br>Number (integer)<br>Operating cycles at Vmax, charging of capacitor<br>Switching cycles at Vmax, failure mode<br>Power<br>Maximum power at 25°C<br>Electrical power<br>Dissipation power<br>Generator internal resistance<br>Minimum resistance<br>Rated resistance<br>Tolerance of RR<br>Parallel resistance<br>PTC resistance<br>Reference resistance<br>Series resistance<br>Resistance at 25°C<br>Resistance matching per reel/ packing unit at 25°C<br>Tolerance of R25<br>Temperature<br>Time<br>Ambient temperature|



Please read _Cautions and warnings_ and _Important notes_ at the end of this document. 

Page 10 of 12 

|ta<br>TC<br>tE<br>TR<br>Tsense<br>Top<br>TPTC<br>tR<br>Tref<br>TRmin<br>tS<br>Tsurf<br>UCT<br>V or Vel<br>Vc(max)<br>VF,max<br>VRMS<br>VBD<br>Vins<br>Vlink,max<br>Vmax<br>Vmax,dyn<br>Vmeas<br>Vmeas,max<br>VR<br>VPTC<br>α<br>∆<br>δth<br>τth<br>λ<br>~~iz~~|Thermal threshold time<br>Ferroelectric Curie temperature<br>Settling time (for level sensors)<br>Rated temperature<br>Sensing temperature<br>Operating temperature<br>PTC temperature<br>Response time<br>Reference temperature<br>Temperature at minimum resistance<br>Switching time<br>Surface temperature<br>Upper category temperature<br>Voltage (with subscript only for distinction from volume)<br>Maximum DC charge voltage of the surge generator<br>Maximum voltage applied at fault conditions in protection mode<br>Root-mean-square value of voltage<br>Breakdown voltage<br>Insulation test voltage<br>Maximum link voltage<br>Maximum operating voltage<br>Maximum dynamic (short-time) operating voltage<br>Measuring voltage<br>Maximum measuring voltage<br>Rated voltage<br>Voltage drop across a PTC thermistor<br>Temperature coefficient<br>Tolerance, change<br>Dissipation factor<br>Thermal cooling time constant<br>Failure rate<br>Lead spacing (in mm)<br>~~iz~~|
|---|---|



+ To be replaced by a letter 

All dimensions are given in mm. 

The commas used in numerical values denote decimal points. 

Please read _Cautions and warnings_ and _Important notes_ at the end of this document. 

Page 11 of 12 

~~Lt~~ **Important notes** 

The following applies to all products named in this publication: 

1. Some parts of this publication contain **statements about the suitability of our products for certain areas of application** . These statements are based on our knowledge of typical requirements that are often placed on our products in the areas of application concerned. We nevertheless expressly point out **that such statements cannot be regarded as binding statements about the suitability of our products for a particular customer application** . As a rule, EPCOS is either unfamiliar with individual customer applications or less familiar with them than the customers themselves. For these reasons, it is always ultimately incumbent on the customer to check and decide whether an EPCOS product with the properties described in the product specification is suitable for use in a particular customer application. 

2. We also point out that **in individual cases, a malfunction of electronic components or failure before the end of their usual service life cannot be completely ruled out in the current state of the art, even if they are operated as specified** . In customer applications requiring a very high level of operational safety and especially in customer applications in which the malfunction or failure of an electronic component could endanger human life or health (e.g. in accident prevention or lifesaving systems), it must therefore be ensured by means of suitable design of the customer application or other action taken by the customer (e.g. installation of protective circuitry or redundancy) that no injury or damage is sustained by third parties in the event of malfunction or failure of an electronic component. 

3. **The warnings, cautions and product-specific notes must be observed.** 

4. In order to satisfy certain technical requirements, **some of the products described in this publication may contain substances subject to restrictions in certain jurisdictions (e.g. because they are classed as hazardous)** . Useful information on this will be found in our Material Data Sheets on the Internet (www.epcos.com/material). Should you have any more detailed questions, please contact our sales offices. 

5. We constantly strive to improve our products. Consequently, **the products described in this publication may change from time to time** . The same is true of the corresponding product specifications. Please check therefore to what extent product descriptions and specifications contained in this publication are still applicable before or when you place an order. We also **reserve the right to discontinue production and delivery of products** . Consequently, we cannot guarantee that all products named in this publication will always be available. The aforementioned does not apply in the case of individual agreements deviating from the foregoing for customer-specific products. 

6. Unless otherwise agreed in individual contracts, **all orders are subject to the current version of the "General Terms of Delivery for Products and Services in the Electrical Industry" published by the German Electrical and Electronics Industry Association (ZVEI)** . 

7. The trade names EPCOS, BAOKE, Alu-X, CeraDiode, CeraLink, CeraPlas, CSMP, CSSP, CTVS, DeltaCap, DigiSiMic, DSSP, FilterCap, FormFit, MiniBlue, MiniCell, MKD, MKK, MLSC, MotorCap, PCC, PhaseCap, PhaseCube, PhaseMod, PhiCap, SIFERRIT, SIFI, SIKOREL, SilverCap, SIMDAD, SiMic, SIMID, SineFormer, SIOV, SIP5D, SIP5K, TFAP, ThermoFuse, WindCap are **trademarks registered or pending** in Europe and in other countries. Further information will be found on the Internet at www.epcos.com/trademarks. 

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