B72660M1140K072

## **SIOV metal oxide varistors** 

SMD varistors for automotive applications, CU types 

**Series/Type: B726*** Date: November 2025 

© TDK Electronics AG 2025. Reproduction, publication and dissemination of this publication, enclosures hereto and the information contained therein without TDK Electronics’ prior express consent is prohibited. 

|**SMD varistors (CU types)**|**SMD varistors (CU types)**|**SMD varistors (CU types)**|||||||**B726***|**B726***|**B726***|
|---|---|---|---|---|---|---|---|---|---|---|---|
|**Automotive series**||||||||||||
|**ype designation system for SMD disk varistor automotive series**||||||||||||
|CU||4032|||K||14||AUTO||G2|
|||||||||||||
|**Construction:**<br>CU�Encapsulated chip||||||||||||
|||||||||||||
|**Case sizes:**<br>3225�32 x 25<br>4032�40 x 32||||||||||||
|||||||||||||
|**Varistor voltage tolerance:**<br>K�±10%||||||||||||
|||||||||||||
|**Maximum RMS operating voltage (VRMS):**<br>14�14 V<br>17�17 V<br>30�30 V||||||||||||
|||||||||||||
|**Automotive series**||||||||||||
|||||||||||||
|**Taping mode:**<br>G2�Taped, 330-mm reel||||||||||||



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

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|**SMD varistors (CU types)**|**B726***|
|---|---|
|**Automotive series**||



## **Construction** 

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Cylindrical varistor element, encapsulated. 

- Encapsulation: thermoplastic, flame-retardant to UL 94 V-0. 

- Termination: tinned copper alloy, suitable for lead-free wave and reflow soldering, and compatible with tin/lead solder. 

## **Features** 

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- 12 V and 24 V supply systems 

- High energy absorption capability 

- SMD plastic package 

- No temperature derating up to 85 ° C 

- RoHS-compatible 

- Suitable for lead-free soldering 

- PSpice simulation modeling available for different pulses 

## **Approvals** 

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UL approved 

## **Delivery mode** 

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Blister tape, 330-mm reel 

- Packing unit: 1000 pcs. 

## **V/I characteristics and derating curves** 

V/I and derating curves are attached to the data sheet. The curves are sorted by VRMS and then by case size, which is included in the type designation. 

## **General technical data** 

|Maximum RMS operating voltage<br>Maximum DC operating voltage<br>Maximum surge current<br>(8/20 µs)<br>Maximum load dump energy<br>(10 pulses)<br>Maximum jump start voltage<br>(5 min)<br>Maximum energy absorption<br>(2 ms)<br>Maximum clamping voltage<br>(8/20 µs)<br>Operating temperature<br>Storage temperature|VRMS<br>VDC<br>imax<br>WLD<br>Vjump<br>Wmax<br>vc,max|14 ... 30<br>16 ... 34<br>100 ... 250<br>6 ... 12<br>25 ... 50<br>400 ... 2000<br>43 ... 93<br>�40/+85<br>�40/+125|V<br>V<br>A<br>J<br>V<br>mJ<br>V<br>°C<br>°C|
|---|---|---|---|



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

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**SMD varistors (CU types) B726* Automotive series** 

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## **Temperature derating** 

Climatic category: �40/+85 ° C 

## **Electrical specifications and ordering codes Maximum ratings (TA = 85** ° **C)** 

|Type|Ordering code|VRMS<br>V|VDC<br>V|imax<br>(8/20 µs)<br>A|Wmax<br>(2 ms)<br>mJ|WLD<br>(10<br>pulses)<br>J|Pmax<br>mW|
|---|---|---|---|---|---|---|---|
|CU3225K14AUTOG2<br>CU4032K14AUTOG2<br>CU3225K17AUTOG2<br>CU4032K17AUTOG2<br>CU3225K30AUTOG2<br>CU4032K30AUTOG2|B72650M1140K072<br>B72660M1140K072<br>B72650M1170K072<br>B72660M1170K072<br>B72650M1300K072<br>B72660M1300K072|14<br>14<br>17<br>17<br>30<br>30|16<br>16<br>20<br>20<br>34<br>34|100<br>250<br>100<br>250<br>100<br>250|400<br>900<br>500<br>1100<br>900<br>2000|6<br>12<br>6<br>12<br>6<br>12|10<br>20<br>10<br>20<br>10<br>20|



**Characteristics (TA = 25** ° **C)** 

|**Characteristics (TA = 25**°**C)**|||||||
|---|---|---|---|---|---|---|
|Type|VV<br>(1 mA)<br>V|∆VV<br>%|Vjump<br>(5 min)<br>V|vc,max<br>V|Ic<br>(8/20 µs)<br>A|Ctyp<br>(1 kHz, 1 V)<br>pF|
|CU3225K14AUTOG2<br>CU4032K14AUTOG2<br>CU3225K17AUTOG2<br>CU4032K17AUTOG2<br>CU3225K30AUTOG2<br>CU4032K30AUTOG2|22<br>22<br>27<br>27<br>47<br>47|±10<br>±10<br>±10<br>±10<br>±10<br>±10|25<br>25<br>30<br>30<br>50<br>50|43<br>43<br>53<br>53<br>93<br>93|1<br>2.5<br>1<br>2.5<br>1<br>2.5|1400<br>2300<br>1200<br>1900<br>600<br>1100|



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

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**SMD varistors (CU types) B726* Automotive series** 

## **Dimensional drawing** 

## Dimensions in mm 

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|Chip size<br>EIA in mm|VRMS,max|l|w|h|
|---|---|---|---|---|
|3225|14, 17, 30|8.0±0.3|6.3±0.3|3.2±0.3|
|4032|14, 17, 30|10.2±0.3|8.0±0.3|3.2±0.3|



## **Recommended solder pad layout** 

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## Dimensions in mm 

|Chip size<br>EIA in mm|A|B|C|
|---|---|---|---|
|3225|3.50|2.80|4.50|
|4032|3.50|2.80|6.50|



## **Delivery mode** 

|EIA case size|Taping|Reel size<br>mm|<br>Packing unit<br>pcs.|Type|Ordering code|
|---|---|---|---|---|---|
|3225<br>3225<br>3225<br>4032<br>4032<br>4032|Blister<br>Blister<br>Blister<br>Blister<br>Blister<br>Blister|330<br>330<br>330<br>330<br>330<br>330|1000<br>1000<br>1000<br>1000<br>1000<br>1000|CU3225K14AUTOG2<br>CU3225K17AUTOG2<br>CU3225K30AUTOG2<br>CU4032K14AUTOG2<br>CU4032K17AUTOG2<br>CU4032K30AUTOG2|B72650M1140K072<br>B72650M1170K072<br>B72650M1300K072<br>B72660M1140K072<br>B72660M1170K072<br>B72660M1300K072|



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

Page 5 of 15 

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|**SMD varistors (CU types)**|**B726***|
|---|---|
|**Automotive series**||



## **Reliability data** 

|**Reliability data**|||
|---|---|---|
|Test|Test methods/conditions|Requirement|
|Varistor voltage|The voltage between two terminals with<br>the specified measuring current applied<br>is called VV (1 mADC@ 0.2 ... 2 s).|To meet the specified value|
|Clamping voltage|The maximum voltage between two<br>terminals with the specified standard<br>impulse current(8/20µs)applied.|To meet the specified value|
|Endurance at upper<br>category temperature|100 h at UCT<br>After having continuously applied the<br>maximum allowable AC voltage at UCT<br>±2°C for 1000 h, the specimen shall be<br>stored at room temperature and normal<br>humidity for 1 to 2 h.<br>Thereafter, the chance of VVshall be<br>measured.||∆V/V (1 mA)|≤10%|
|Load dump|ISO 7637-2<br>Number of pulses: 10<br>Pulse interval: 60 s<br>Pulse duratin: 500 ms||∆V/V (1 mA)|≥-15%<br>No visible damage|
|Jump start|VDC, load= Vjump; 5 min duration<br>14 V (S…K14AUTO…); Vjump= 25 V<br>17 V (S…K17AUTO…); Vjump= 30 V<br>30 V(S…K30AUTO…); Vjump= 45 V||∆V/V (1 mA)|≥-15%<br>No visible damage|
|Fast temperature cycling|IEC 60068-2-14, test Na, LCT/UCT,<br>dwell time 15 min, 100 cycles||∆V/V (1 mA)|≤5%<br>No visible damage|
|Damp heat|IEC 60068-2-67, test Cy, 85°C,<br>85% r. H., VDC, 1000 h||∆V/V (1 mA)|≤10%<br>No visible damage|
|Substrate bending test|IEC 60068-2-21, test Ue1<br>Deflection = 2 mm<br>t = 60 s||∆V/V (1 mA)|≤10%<br>No visible damage|
|Shear test|IEC 60068-2-21, test Ue3<br>Force = 5 N<br>t = 10±1 s||∆V/V (1 mA)|≤10%<br>No visible damage|



## **Note:** 

UCT = Upper category temperature LCT = Lower category temperature 

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

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## **SMD varistors (CU types) B726* Automotive series** 

## **V/I characteristics** 

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## **CU3225 ... AUTOG2** 

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**CU4032 ... AUTOG2** 

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

Page 7 of 15 

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**SMD varistors (CU types) Automotive series** 

**B726*** 

## **Derating curves** 

Maximum surge current Isurge,max = f (tr, pulse train) For explanation of the derating curves refer to "General technical information", chapter 2.7.2 

## **CU3225K14AUTOG2 ... K30AUTOG2** 

## **CU4032K14AUTOG2 ... K30AUTOG2** 

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

Page 8 of 15 

|**SMD varistors (CU types)**|**B726***|
|---|---|
|**Automotive series**||
|**Taping and packing for CU varistors**||



**Blister tape** (taping to IEC 60286-3) 

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## **Dimensions in mm** 

|Symbol|Case size<br>3225<br>4032|Tolerance|
|---|---|---|
|Compartment width<br>A0<br>Compartment length<br>B0<br>Thickness cover tape<br>K0<br>Overall thickness<br>T2<br>Thickness tape<br>T|7.0<br>8.6<br>8.70<br>10.6<br>5.00<br>5.50<br>0.30|±0.20<br>±0.20<br>max.<br>max.<br>max.|
|Sprocket hole diameter<br>D0<br>Sprocket hole diameter<br>D1|1.50<br>1.50|+0.10/�0<br>min.|
|Sprocket hole pitch<br>P0<br>Distance center hole to center compartment<br>P2<br>Pitch of the component compartments<br>P1|4.00<br>2.00<br>12.00|±0.101)<br>±0.05<br>±0.10|
|Tape width<br>W<br>Distance edge to center of hole<br>E<br>Distnace center hole to center compartment<br>F<br>Distance compartment to edge<br>G|16.00<br>1.75<br>7.50<br>0.75|±0.30<br>±0.10<br>±0.05<br>min.|



1) ≤ 0.2 mm over 10 sprocket holes 

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

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|**SMD varistors (CU types)**|**B726***|
|---|---|
|**Automotive series**||



## **Additional taping information** 

|**ditional taping information**||
|---|---|
|el material|Polystyrol(PS)|
|e material|Polystyrol(PS)or Polycarbonat(PC),PVC or PET|
|e break force|min. 10 N|
|cover tape strength|min. 10 N|
|e peel angle|Angle between top cover tape and the direction of feed<br>during peel off: 165°to 180°|
|vity play|Each part rests in the cavity so that the angle between<br>thepart and cavitycenter line is no more than 20°|



## **Reel packing** 

Packing material: Plastic 

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## **Dimensions in mm** 

|Reel diameter<br>Reel width (inside)<br>|A<br>W1<br><br>|Dimension<br>330<br>16.4<br>|Tolerance<br>+0/�2.0<br>+1.5/�0|
|---|---|---|---|



## **Packing unit: 1000 pcs./ reel** 

## **Leader, trailer** 

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

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|**SMD varistors (CU types)**|**B726***|
|---|---|
|**Automotive series**||



## **Cautions and warnings** 

## **General** 

1. TDK metal oxide varistors 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 TDK Electronics during the design-in-phase. 

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

3. For applications of SIOVs in line-to-ground circuits based on various international and local standards there are restrictions existing or additional safety measures required. 

## **Storage** 

1. Store SIOVs only in original packaging. Do not open the package prior to processing. 

2. Recommended storage conditions in original packaging: Storage temperature: �25 ° C ... +45 ° C, Relative humidity: <75% annual average, <95% on maximum 30 days a year. 

Dew precipitation: is to be avoided. 

3. Avoid contamination of an SIOV's during storage, handling and processing. 

4. Avoid storage of SIOVs in harmful environments that can affect the function during long-term operation (examples given under operation precautions). 

5. The SIOV type series should be soldered after shipment from TDK Electronics within the time specified: 

SIOV-S, -Q, -LS, -B, -SNF 24 months ETFV/ T series, -CU 12 months. 

## **Handling** 

1. SIOVs must not be dropped. 

2. Components must not be touched with bare hands. Gloves are recommended. 

3. Avoid contamination of the surface of SIOV electrodes during handling, be careful of the sharp edge of SIOV electrodes. 

## **Soldering (where applicable)** 

1. Use rosin-type flux or non-activated flux. 

2. Insufficient preheating may cause ceramic cracks. 

3. Rapid cooling by dipping in solvent is not recommended. 

4. Complete removal of flux is recommended. 

5. Temperatures of all preheat stages and the solder bath must be strictly controlled especially for T series (T14 and T20). 

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

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|**SMD varistors (CU types)**|**B726***|
|---|---|
|**Automotive series**||



## **Mounting** 

1. Potting, sealing or adhesive compounds can produce chemical reactions in the SIOV ceramic that will degrade the component’s electrical characteristics. 

2. Overloading SIOVs may result in ruptured packages and expulsion of hot materials. For this reason SIOVs should be physically shielded from adjacent components. 

## **Operation** 

1. Use SIOVs only within the specified temperature operating range. 

2. Use SIOVs only within the specified voltage and current ranges. 

3. Environmental conditions must not harm SIOVs. Use SIOVs 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. 

## **Display of ordering codes for TDK Electronics products** 

The ordering code for one and the same product can be represented differently in data sheets, data books, other publications, on the company website, or in order-related documents such as shipping notes, order confirmations and product labels. **The varying representations of the ordering codes are due to different processes employed and do not affect the specifications of the respective products** . Detailed information can be found on the Internet under www.tdk-electronics.tdk.com/orderingcodes. 

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

Page 12 of 15 

|**SMD varistors (CU types)**|**B726***|
|---|---|
|**Automotive series**||



## **Symbols and terms** 

|**Symbols and**|**terms**|
|---|---|
|Symbol|Term|
|C<br>Ctyp<br>i<br>ic<br>Ileak<br>imax<br>Imax<br>In<br>LCT<br>Ltyp<br>Pmax<br>Rins<br>Rmin<br>TA<br>tr<br>UCT<br>v<br>Vclamp<br>vc, max<br>VDC<br>Vjump<br>vmax<br>Vop<br>VRMS<br>VRMS, op, max<br>Vsurge<br>VV<br>∆VV<br>WLD<br>Wmax|Capacitance<br>Typical capacitance<br>Current<br>Current at which Vc, maxis measured<br>Leakage current<br>Maximum surge current (also termed peak current)<br>Maximum discharge current<br>Nominal discharge current to UL 1449<br>Lower category temperature<br>Typical inductance<br>Maximum average power dissipation<br>Insulation resistance<br>Minimum resistance<br>Ambient temperature<br>Duration of equivalent rectangular wave<br>Upper category temperature<br>Voltage<br>Clamping voltage<br>Maximum clamping voltage at specified current ic<br>DC operating voltage<br>Maximum jump start voltage<br>Maximum voltage<br>Operating voltage<br>AC operating voltage, root-mean-square value<br>Root-mean-square value of max. DC operating voltage incl. ripple current<br>Super imposed surge voltage<br>Varistor voltage<br>Tolerance of varistor voltage<br>Maximum load dump<br>Maximum energy absorption<br>Lead spacing|



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 13 of 15 

## **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 bindin g statements about the suitability of our products for a particular customer application** . As a rule we are 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 a 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 th e 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 life-saving 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 th  is publication may contain substances subject to restrictions in certain jurisdiction s (e.g. because they are classed as hazardous)** . Useful information on this will be found in our Material Data Sheets on the Internet (www.tdk-electronics.tdk.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 th  is 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 our General Terms and Conditions of Supply** . 

Page 14 of 15 

## **Important notes** 

7. **Our manufacturing sites serving the automotive business apply the IATF 16949 standard** . The IATF certifications confirm our compliance with requirements regarding the quality management system in the automotive industry. Referring to customer requirements and customer specific requirements (“CSR”) TDK always has and will continue to have the policy of respecting individual agreements. Even if IATF 16949 may appear to support the acceptance of unilateral requirements, we hereby like to emphasize that **only requirements mutually agreed upon can and will be implemented in our Quality Management System** . For clarification purposes we like to point out that obligations from IATF 16949 shall only become legally binding if individually agreed upon. 

8. The trade names EPCOS, CarXield, CeraCharge, CeraDiode, CeraLink, CeraPad, CeraPlas, CSMP, CTVS, DeltaCap, DigiSiMic, FilterCap, FormFit, InsuGate, LeaXield, MediPlas, MiniBlue, MiniCell, MKD, MKK, ModCap, MotorCap, PCC, PhaseCap, PhaseCube, PhaseMod, PhiCap, PiezoBrush, PlasmaBrush, PowerHap, PQSine, PQvar, SIFERRIT, SIFI, SIKOREL, SilverCap, SIMDAD, SiMic, SIMID, SineFormer, SIOV, SurfIND, ThermoFuse, WindCap, XieldCap are **trademarks registered or pending** in Europe and in other countries. Further information will be found on the Internet at www.tdk-electronics.tdk.com/trademarks. 

Release 2024-02 

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