PTC thermistors for overcurrent
protection and as inrush current limiters
Leaded disks, 260 V up to 1000 V
Series/Type: B597**C0... / B594**C1...
Date: February 2018
© EPCOS AG 2018. Reproduction, publication and dissemination of this publication, enclosures hereto and the
information contained therein without EPCOS' prior express consent is prohibited.
EPCOS AG is a TDK Group Company.
Applications
Inrush current limiter for smoothing and
DC link capacitors
To replace high-power fixed resistors for
capacitor charging
Overcurrent and short circuit protection
Features
Lead-free terminals
Self-protecting in case of malfunction of
short-circuit relay or internal short circuit of
capacitor
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 (file number
E69802) for ICL application selected types;
Vmax = 480 V and VR= 400 V for C755
UL approval to UL 1434 (file number
E69802) for overcurrent protection
Vmax = 420 V and VR= 380 V, except type
C758, C1412 and C1451
VDE approval (licence number 40040539)
for ICL applications and for overcurrent
protection selected types
(licence number 104843)
IECQ certificate (file number 101-QA-13) for
ICL applications and for overcurrent
protection selected types
(file number 101-QA-2)
Qualification based on AEC-Q200, Rev. D
for B59412C1130B070 and
B59451C1130B070
RoHS-compatible
Delivery mode
Cardboard strips (standard)
Cardboard tape reeled or in Ammo pack on
request
Dimensional drawing with coating,
C14** and C7**
Dimensional drawing without coating,
B750 and B770
Dimensions in mm
Type wmax hmax lmin thmax ∅d
B750 12.5 16.5 35 5.0 0.6
B770 8.5 12.0 25 7.0 0.6
C1412 15.0 19.0 35 7.5 0.8
C1451 15.0 19.0 35 7.5 0.8
C750 13.0 18.0 35 5.5 0.6
C751 13.0 18.0 35 7.5 0.6
C752 13.0 18.0 25 7.5 0.6
C753 13.0 18.0 25 7.5 0.6
C754 13.0 18.0 25 7.5 0.6
C755 13.0 18.0 35 7.5 0.6
C758 13.0 18.0 35 7.5 0.6
C770 9.0 13.5 25 7.5 0.6
C771 9.0 13.5 25 7.5 0.6
C772 9.0 13.5 25 7.5 0.6
C773 9.0 13.5 25 7.5 0.6
C774 9.0 13.5 25 7.5 0.6
Overcurrent protection and inrush current limiting
Leaded disks, 260 V up to 1000 V
Page 2 of 23Please read Cautions and warnings and
Important notes at the end of this document.
General technical data for inrush current limiters
Operating cycles at Vmax (charging of capacitor) Nc> 100.000 cycles
Switching cycles at Vmax (failure mode) Nf> 100 cycles
Operating temperature range (V = 0) Top 40/+125 °C
Operating temperature range (V = Vmax) Top 20/+85 °C
Electrical specifications and ordering codes for inrush current limiters
Type Vmax
V AC
Vlink,max
V DC
RR
Ω
∆RR
%
Tref
(typ.)
°C
Cth
J/K
τth
s
Circuit
diagram
IECQ
Approvals Ordering code
C770 260 370 70 ±25 120 0.4 70 2 B59770C0120A070
C771 260 370 120 ±25 120 0.6 80 2 B59771C0120A070
C772 260 370 150 ±25 120 0.6 80 2 B59772C0120A070
C750 280 400 25 ±25 120 1.0 100 2 X X B59750C0120A070
C751 280 400 50 ±25 120 1.4 120 2 X X B59751C0120A070
C752 280 400 80 ±25 120 1.4 120 2 X X B59752C0120A070
C1451 440 620 56 ±25 130 2.1 100 1, 2, 3 X X B59451C1130B070
C753 440 620 120 ±25 120 1.4 120 1, 2, 3 X X B59753C0120A070
C754 440 620 150 ±25 120 1.4 120 1, 2, 3 X X B59754C0120A070
C773 440 620 500 ±25 120 0.6 80 1, 2, 3 B59773C0120A070
C774 440 620 1100 ±25 115 0.6 80 1, 2, 3 B59774C0115A070
C1412 480 680 120 ±25 130 2.1 100 1, 2, 3 X X B59412C1130B070
C755 560 800 500 ±25 115 1.4 120 1, 2, 3 X B59755C0115A070
Overcurrent protection and inrush current limiting
Leaded disks, 260 V up to 1000 V
Page 3 of 23Please read Cautions and warnings and
Important notes at the end of this document.
Circuit diagrams
➀Three phases circuit
➁Single phase circuit
➂DC circuit
Overcurrent protection and inrush current limiting
Leaded disks, 260 V up to 1000 V
Page 4 of 23Please read Cautions and warnings and
Important notes at the end of this document.
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:
K K factor
K = 1 for DC source
K = 0.96 for 3-phase bridge rectifier
K = 0.76 for single phase bridge rectifier
N Number of required PTC thermistors connected in parallel
C Capacitance of smoothing or DC link capacitor in F
V Charging voltage of capacitor in V
Cth Heat capacity in 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.
Overcurrent protection and inrush current limiting
Leaded disks, 260 V up to 1000 V
Page 5 of 23Please read Cautions and warnings and
Important notes at the end of this document.
General technical data for overcurrent protection
Switching cycles N 100
Operating temperature range (V = 0) Top 40/+125 °C
Operating temperature range (V = Vmax) Top 0/+60 °C
Electrical specifications and ordering codes for overcurrent protection
Type IR
mA
IS
mA
ISmax
(V = Vmax)
A
Ir
(typ.)
(V = Vmax)
mA
RR
Ω
Rmin
ΩIECQ
Approvals Ordering code
Vmax = 440 V DC or V AC, VR= 400 V DC or V AC, Tref = 120 °C (typ.), ∆RR=±25 %
B750 123 245 4.0 4 25 13 X X B59750B0120A070
B770 64 127 2.8 3.0 70 45 X X B59770B0120A070
C751 87 173 4.0 3.5 50 26 X X B59751C0120A070
C752 69 137 4.0 3.5 80 42 X X B59752C0120A070
C753 56 112 4.0 3.0 120 63 X X B59753C0120A070
C754 50 100 4.0 3.0 150 68 X X B59754C0120A070
C771 49 97 2.8 2.5 120 76 X X B59771C0120A070
C772 43 86 2.8 2.5 150 96 X X B59772C0120A070
Vmax = 440 V DC or V AC, VR= 400 V DC or V AC, Tref = 130 °C (typ.), ∆RR=±25 %
C1412 75 150 7.0 6.0 120 63 B59412C1130B070
C1451 100 200 12.0 7.0 56 29 B59451C1130B070
Vmax = 550 V DC or V AC, VR= 500 V DC or V AC, Tref = 115 °C (typ.), ∆RR=±25 %
C755 28 55 1.4 2.0 500 230 X X B59755C0115A070
C774 16 32 1.0 1.5 1100 700 X X B59774C0115A070
Vmax = 550 V DC or V AC, VR= 500 V DC or V AC, Tref = 120 °C (typ.), ∆RR=±25 %
C773 24 48 1.0 2.0 500 320 X X B59773C0120A070
Vmax = 1000 V DC or V AC, VR= 1000 V DC or V AC, Tref = 110 °C (typ.), ∆RR=±33 %
C758 8 17 0.5 3.0 7500 3380 B59758C0110A070
Circuit diagram
Overcurrent protection and inrush current limiting
Leaded disks, 260 V up to 1000 V
Page 6 of 23Please read Cautions and warnings and
Important notes at the end of this document.
Reliability data for inrush current limiters and overcurrent protection
Test Standard Test conditions ∆R25/R25
Electrical endurance,
cycling
IEC 60738-1 Overcurrent
protection
Inrush current limiters
Room temperature,
IS,max, Vmax
Number of cycles: 100
Room temperature, Vlink,max
applied energy
< Cth (Tref TA)
Number of cycles: 100 000
< 25%
Electrical endurance,
constant
IEC 60738-1 Storage at Vmax and Top,max (@ Vmax)
Test duration: 1000 h
< 25%
Damp heat IEC 60738-1 Temperature of air: 40 °C
Relative humidity of air: 93%
Duration: 56 days
Test according to IEC 60068-2-78
< 10%
Rapid change
of temperature
IEC 60738-1 T1= Top,min (0 V), T2= Top,max (0 V)
Number of cycles: 5
Test duration: 30 min
Test according to IEC 60068-2-14, test Na
< 10%
Vibration IEC 60738-1 Frequency range: 10 to 55 Hz
Displacement amplitude: 0.75 mm
Test duration: 3 ×2 h
Test according to IEC 60068-2-6, test Fc
< 5%
Shock IEC 60738-1 Acceleration : 500 m/s2
Pulse duration: 11 ms; 6 x 3 pulses
< 5%
Climatic sequence IEC 60738-1 Dry heat: T = Top,max (0 V)
Test duration: 16 h
Damp heat first cycle
Cold: T = Top,min (0 V)
Test duration: 2 h
Damp heat 5 cycles
Tests performed according to
IEC 60068-2-30
< 10%
Overcurrent protection and inrush current limiting
Leaded disks, 260 V up to 1000 V
Page 7 of 23Please read Cautions and warnings and
Important notes at the end of this document.
Characteristics (typical)
PTC resistance RPTC versus
PTC temperature TPTC
(measured at low signal voltage)
Minimum resistance of PTC thermistors
versus applied voltage (pulsed)
Residual current in high-ohmic state Ires as
function of applied voltage VPTC, typical
(measured at 25 °C in still air)
Switching time tSversus switching current IS
(measured at 25 °C in still air)
Overcurrent protection and inrush current limiting
Leaded disks, 260 V up to 1000 V
Page 8 of 23Please read Cautions and warnings and
Important notes at the end of this document.
Characteristics (typical)
PTC current IPTC versus PTC voltage VPTC
(measured at 25 °C in still air)
Rated current IRversus ambient temperature TA
(measured in still air)
Overcurrent protection and inrush current limiting
Leaded disks, 260 V up to 1000 V
Page 9 of 23Please read Cautions and warnings and
Important notes at the end of this document.
Characteristics (typical)
PTC resistance RPTC versus
PTC temperature TPTC
(measured at low signal voltage)
Minimum resistance of PTC thermistors
versus applied voltage (pulsed)
Residual current in high-ohmic state Ires as
function of applied voltage VPTC, typical
(measured at 25 °C in still air)
Switching time tSversus switching current IS
(measured at 25 °C in still air)
Overcurrent protection and inrush current limiting
Leaded disks, 260 V up to 1000 V
Page 10 of 23Please read Cautions and warnings and
Important notes at the end of this document.
Characteristics (typical)
PTC current IPTC versus PTC voltage VPTC
(measured at 25 °C in still air)
Rated current IRversus ambient temperature TA
(measured in still air)
Overcurrent protection and inrush current limiting
Leaded disks, 260 V up to 1000 V
Page 11 of 23Please read Cautions and warnings and
Important notes at the end of this document.
Characteristics (typical)
PTC resistance RPTC versus
PTC temperature TPTC
(measured at low signal voltage)
Minimum resistance of PTC thermistors
versus applied voltage (pulsed)
Residual current in high-ohmic state Ires as
function of applied voltage VPTC, typical
(measured at 25 °C in still air)
Switching time tSversus switching current IS
(measured at 25 °C in still air)
Overcurrent protection and inrush current limiting
Leaded disks, 260 V up to 1000 V
Page 12 of 23Please read Cautions and warnings and
Important notes at the end of this document.
Characteristics (typical)
PTC current IPTC versus PTC voltage VPTC
(measured at 25 °C in still air)
Rated current IRversus ambient temperature TA
(measured in still air)
Overcurrent protection and inrush current limiting
Leaded disks, 260 V up to 1000 V
Page 13 of 23Please read Cautions and warnings and
Important notes at the end of this document.
Characteristics (typical)
PTC resistance RPTC versus
PTC temperature TPTC
(measured at low signal voltage)
Minimum resistance of PTC thermistors
versus applied voltage (pulsed)
Residual current in high-ohmic state Ires as
function of applied voltage VPTC, typical
(measured at 25 °C in still air)
Switching time tSversus switching current IS
(measured at 25 °C in still air)
Overcurrent protection and inrush current limiting
Leaded disks, 260 V up to 1000 V
Page 14 of 23Please read Cautions and warnings and
Important notes at the end of this document.
Characteristics (typical)
PTC current IPTC versus PTC voltage VPTC
(measured at 25 °C in still air)
Rated current IRversus ambient temperature TA
(measured in still air)
Overcurrent protection and inrush current limiting
Leaded disks, 260 V up to 1000 V
Page 15 of 23Please read Cautions and warnings and
Important notes at the end of this document.
Characteristics (typical)
PTC resistance RPTC versus
PTC temperature TPTC
(measured at low signal voltage)
Minimum resistance of PTC thermistors
versus applied voltage (pulsed)
Residual current in high-ohmic state Ires as
function of applied voltage VPTC, typical
(measured at 25 °C in still air)
Switching time tSversus switching current IS
(measured at 25 °C in still air)
Overcurrent protection and inrush current limiting
Leaded disks, 260 V up to 1000 V
Page 16 of 23Please read Cautions and warnings and
Important notes at the end of this document.
Characteristics (typical)
PTC current IPTC versus PTC voltage VPTC
(measured at 25 °C in still air)
Rated current IRversus ambient temperature TA
(measured in still air)
Overcurrent protection and inrush current limiting
Leaded disks, 260 V up to 1000 V
Page 17 of 23Please read Cautions and warnings and
Important notes at the end of this document.
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 ther-
mistors should be evaluated taking into consideration worst-case conditions.
Storage
Store thermistors only in original packaging. Do not open the package prior to processing.
Storage conditions in original packaging: storage temperature 25 °C ... +45 °C, relative hu-
midity ≤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 opera-
tion (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 1210 and smaller: 12 months
Handling
PTCs must not be dropped. Chip-offs must not be caused during handling of PTCs.
The ceramic and metallization of the 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.
Overcurrent protection and inrush current limiting
Leaded disks, 260 V up to 1000 V
Page 18 of 23Please read Cautions and warnings and
Important notes at the end of this document.
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. Es-
pecially 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 and pressure of the clamping contacts pressing against the PTC must be
10 N and 50 kPa, respectively. In case the assembly is exposed to mechanical shock and/ or
vibration this force should be higher in order to avoid movement of the PTC during operation.
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 at-
mospheric conditions. Avoid use in deoxidizing gases (chlorine gas, hydrogen sulfide gas, am-
monia 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.
Display of ordering codes for EPCOS products
The ordering code for one and the same EPCOS product can be represented differently in data
sheets, data books, other publications, on the EPCOS 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.epcos.com/orderingcodes
Overcurrent protection and inrush current limiting
Leaded disks, 260 V up to 1000 V
Page 19 of 23Please read Cautions and warnings and
Important notes at the end of this document.
Symbols and terms
Symbol Term
AArea
CCapacitance
Cth Heat capacity
fFrequency
ICurrent
Imax Maximum current
IRRated current
Ires Residual current
IPTC PTC current
IrResidual currrent
Ir,oil Residual currrent in oil (for level sensors)
Ir,air Residual currrent in air (for level sensors)
IRMS Root-mean-square value of current
ISSwitching current
ISmax Maximum switching current
LCT Lower category temperature
NNumber (integer)
NcOperating cycles at Vmax, charging of capacitor
NfSwitching cycles at Vmax, failure mode
PPower
P25 Maximum power at 25 °C
Pel Electrical power
Pdiss Dissipation power
RGGenerator internal resistance
Rmin Minimum resistance
RRRated resistance @ rated temperature TR
∆RRTolerance of RR
RPParallel resistance
RPTC PTC resistance
Rref Reference resistance
RSSeries resistance
R25 Resistance at 25 °C
R25,match Resistance matching per reel/ packing unit at 25 °C
∆R25 Tolerance of R25
Overcurrent protection and inrush current limiting
Leaded disks, 260 V up to 1000 V
Page 20 of 23Please read Cautions and warnings and
Important notes at the end of this document.
T Temperature
tTime
TAAmbient temperature
taThermal threshold time
TCFerroelectric Curie temperature
tESettling time (for level sensors)
TRRated temperature @ 25 °C or otherwise specified in the data sheet
Tsense Sensing temperature
Top Operating temperature
TPTC PTC temperature
tRResponse time
Tref Reference temperature
TRmin Temperature at minimum resistance
tSSwitching time
Tsurf Surface temperature
UCT Upper category temperature
V or Vel Voltage (with subscript only for distinction from volume)
Vc(max) Maximum DC charge voltage of the surge generator
VF,max Maximum voltage applied at fault conditions in protection mode
VRMS Root-mean-square value of voltage
VBD Breakdown voltage
Vins Insulation test voltage
Vlink,max Maximum link voltage
Vmax Maximum operating voltage
Vmax,dyn Maximum dynamic (short-time) operating voltage
Vmeas Measuring voltage
Vmeas,max Maximum measuring voltage
VRRated voltage
VPTC Voltage drop across a PTC thermistor
αTemperature coefficient
∆Tolerance, change
δth Dissipation factor
τth Thermal cooling time constant
λFailure rate
Lead spacing (in mm)
Overcurrent protection and inrush current limiting
Leaded disks, 260 V up to 1000 V
Page 21 of 23Please read Cautions and warnings and
Important notes at the end of this document.
Page 22 of 23
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 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 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 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 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.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 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 our General Terms
and Conditions of Supply.
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.
Page 23 of 23
Important notes
8. The trade names EPCOS, CeraCharge, CeraDiode, CeraLink, CeraPad, CeraPlas, CSMP, CTVS,
DeltaCap, DigiSiMic, ExoCore, FilterCap, FormFit, LeaXield, MiniBlue, MiniCell, MKD, MKK,
MotorCap, PCC, PhaseCap, PhaseCube, PhaseMod, PhiCap, PowerHap, PQSine, PQvar,
SIFERRIT, SIFI, SIKOREL, SilverCap, SIMDAD, SiMic, SIMID, SineFormer, SIOV, ThermoFuse,
WindCap 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 2018-10