1© KEMET Electronics Corporation • P.O. Box 5928 • Greenville, SC 29606 • 864-963-6300 • www.kemet.com A4024_PEH534 • 2/7/2017
One world. One KEMET
Benets
• Snap-In
3,000 hours at +105°C (VR, IR applied)
PCB mounting
Low ESR and ESL
High ripple current
Overview
KEMET's PEH534 is a long-life electrolytic capacitor
designed to offer high ripple current capability and low
mounting cost. Low ESR is the result of a very low resistive
paper/electrolyte system. Low ESR, together with the TDC
thermal concept, gives the PEH534 a high ripple current
capability.
Applications
Typical applications for KEMET's PEH534 capacitor include
switch mode power supplies (SMPS), drives, welding
equipment, uninterruptible power supplies (UPS), and other
power electronic applications where high current ratings
and compact size are important.
Snap-In Aluminum Electrolytic Capacitors
PEH534 Series, +105°C
Part Number System
PEH534 JBC 456 0M 2
Series Rated Voltage (VDC) Size Code Capacitance Code
(µF) Version Capacitance
Tolerance Termination
Snap-In type
Aluminum
Electrolytic
J = 35
M = 63
P = 100
R = 200
S = 250
U = 350
V = 400
Y = 450
See Dimension
Table
The last two
digits represent
signicant gures.
The rst digit
indicates the total
number digits.
0 = Standard M = ±20% See Termination
Table
Click image above for interactive 3D content
Open PDF in Adobe Reader for full functionality
2© KEMET Electronics Corporation • P.O. Box 5928 • Greenville, SC 29606 • 864-963-6300 • www.kemet.com A4024_PEH534 • 2/7/2017
Snap-In Aluminum Electrolytic Capacitors – PEH534, +105°C
Performance Characteristics
Item Performance Characteristics
Capacitance Range 150 – 22,000 µF
Rated Voltage 35 – 450 VDC
Operating Temperature −40 to +105°C
Capacitance Tolerance ±20% at 100 Hz/+20°C
Operational Lifetime D (mm) Rated Voltage and Ripple Current at
+105°C (hours) Rated Voltage at +105°C (hours)
22 – 40 3,000 4,000
Shelf Life 4 years at +40°C 0 VDC
Leakage Current I = 0.003 CV (µA)
C = rated capacitance (µF), V = rated voltage (VDC). Voltage applied for 5 minutes at +20°C.
Vibration Test Specications
Procedure Requirements
0.75 mm displacement amplitude
or 10 g maximum acceleration.
Vibration applied for three 2-hour
sessions at 10 – 500 Hz (Capacitor
clamped by body).
No leakage of electrolyte or other visible damage. Deviations in
capacitance from initial measurements must not exceed: Δ C/C < 5%
Standards IEC 60384–4 long life grade 40/105/56, in accordance with CECC 30 301–809
Test Method & Performance
Endurance Life Test
Conditions Performance
Temperature +105°C
Test Duration 2,000 hours
Ripple Current Maximum ripple current specied in table
Voltage The sum of DC voltage and the peak AC voltage must not exceed the rated voltage of the capacitor
Performance The following specications will be satised when the capacitor is tested at +20°C:
Capacitance Change
≤ 160 V Within 15% of the initial value
> 160 V Within 10% of the initial value
Equivalent Series Resistance Does not exceed 200% of the initial value
Leakage Current Does not exceed leakage current limit
3© KEMET Electronics Corporation • P.O. Box 5928 • Greenville, SC 29606 • 864-963-6300 • www.kemet.com A4024_PEH534 • 2/7/2017
Snap-In Aluminum Electrolytic Capacitors – PEH534, +105°C
Dimensions – Millimeters
D X L Size Code
Dimensions in mm Approximate
Weight
Grams
D1 L1
±0.5 ±1.0
25 x 30
BC
25.5
31
21
25 x 35
BD
25.5
36
24
25 x 40
BE
25.5
41
27
25 x 45
BF
25.5
46
30
25 x 50
BG
25.5
51
33
30 x 25
CB
30.5
26
24
30 x 30
CC
30.5
31
29
30 x 35
CD
30.5
36
34
30 x 40
CE
30.5
41
39
30 x 45
CF
30.5
46
45
30 x 50
CG
30.5
51
51
35 x 25
DB
35.5
26
32
35 x 30
DC
35.5
31
40
35 x 35
DD
35.5
36
48
35 x 40
DE
35.5
41
56
35 x 45
DF
35.5
46
64
35 x 50
DG
35.5
51
72
Note: Add 0.5 mm to D and 1 mm to L for Sleeving
4© KEMET Electronics Corporation • P.O. Box 5928 • Greenville, SC 29606 • 864-963-6300 • www.kemet.com A4024_PEH534 • 2/7/2017
Snap-In Aluminum Electrolytic Capacitors – PEH534, +105°C
Termination Tables
Termination Code 22S 3 4 4S
Diameter (mm)
25
30
35
Mounting: These capacitors are designed to be mounted by their terminations alone and may be used in any
position. Dummy pins on 4-pin decks must be isolated.
Termination
Code
Termination
Style
LL
±1
Standard Termination Option
2 2 Pin 6.3
Other Termination Options
2S 2 Pin 4
3 3 Pin 4
4 4 Pin 6.3
4S 4 Pin 4
Dimensions in mm
L
SIDE VIEW TERMINAL
END VIEW
D
PCB LAYOUT
2 ±0.1
Style 2/2S
L
SIDE VIEW TERMINAL
END VIEW
D
5.8 ±1
PCB LAYOUT
4.75 ±0.1
Style 3
L
SIDE VIEW TERMINAL
END VIEW
D
5.8 ±1
PCB LAYOUT
Style 4/4S
LL
+
-
3.3 ±0.1
Ø2.5 Minimum
+ ve
Ø2 ±0.1 Typical
+
-
30°
30°
- ve
4 Holes Ø2 ±0.1
on a Ø22.5 PCD
+ ve
5© KEMET Electronics Corporation • P.O. Box 5928 • Greenville, SC 29606 • 864-963-6300 • www.kemet.com A4024_PEH534 • 2/7/2017
Snap-In Aluminum Electrolytic Capacitors – PEH534, +105°C
Shelf Life
The capacitance, ESR and impedance of a capacitor will not change signicantly after extended storage periods, however
the leakage current will very slowly increase. KEMET products are particularly stable and allow a shelf life in excess of three
years at 40°C. See sectional specication under each product series for specic data.
Re-age (Reforming) Procedure
Apply the rated voltage to the capacitor at room temperature for a period of one hour, or until the leakage current has fallen
to a steady value below the specied limit. During re-aging a maximum charging current of twice the specied leakage
current or 5 mA (whichever is greater) is suggested.
Reliability
The reliability of a component can be dened as the probability that it will perform satisfactorily under a given set of
conditions for a given length of time.
In practice, it is impossible to predict with absolute certainty how any individual component will perform; thus, we must
utilize probability theory. It is also necessary to clearly dene the level of stress involved (e.g. operating voltage, ripple
current, temperature and time). Finally, the meaning of satisfactory performance must be dened by specifying a set of
conditions which determine the end of life of the component.
Reliability as a function of time, R(t), is normally expressed as: R(t)=e-λt
where R(t) is the probability that the component will perform satisfactorily for time t, and λ is the failure rate.
Failure Rate
The failure rate is the number of components failing per unit time. The failure rate of most electronic components follows
the characteristic pattern:
Early failures are removed during the manufacturing process.
The operational life is characterized by a constant failure rate.
The wear out period is characterized by a rapidly increasing failure rate.
The failures in time (FIT) are given with a 60% condence level for the various type codes. By convention, FIT is expressed as
1 x 10-9 failures per hour. Failure rate is also expressed as a percentage of failures per 1,000 hours.
e.g., 100 FIT = 1 x 10-7 failures per hour = 0.01%/1,000 hours
End of Life Denition
Catastrophic Failure: short circuit, open circuit or safety vent operation
Parametric Failure:
Change in capacitance > ±10%
Leakage current > specied limit
ESR > 2 x initial ESR value
6© KEMET Electronics Corporation • P.O. Box 5928 • Greenville, SC 29606 • 864-963-6300 • www.kemet.com A4024_PEH534 • 2/7/2017
Snap-In Aluminum Electrolytic Capacitors – PEH534, +105°C
MTBF
The mean time between failures (MTBF) is simply the inverse of the failure rate.
MTBF= 1/λ
wear out
early failures
operational life
Failure Rate
Time
The failure rate is derived from our periodic test results. The failure rate (λR) is, therefore, only given at test temperature for
life tests. An estimation is also given at 40°C. The expected failure rate for this capacitor range is based on our periodic test
results for capacitors with structural similarity. Failure rate is frequently quoted in FIT (Failures In Time) where 1 FIT = 1 x 10-9
failures per hour. Failure rate per hour includes both catastrophic and parametric failures.
Environmental Compliance
As an environmentally conscious company, KEMET is working continuously with improvements concerning the environmental
effects of both our capacitors and their production. In Europe (RoHS Directive) and in some other geographical areas like
China, legislation has been put in place to prevent the use of some hazardous materials, such as lead (Pb), in electronic
equipment. All products in this catalog are produced to help our customers’ obligations to guarantee their products and fulll
these legislative requirements. The only material of concern in our products has been lead (Pb), which has been removed
from all designs to fulll the requirement of containing less than 0.1% of lead in any homogeneous material. KEMET will
closely follow any changes in legislation world wide and makes any necessary changes in its products, whenever needed.
Some customer segments such as medical, military and automotive electronics may still require the use of lead in electrode
coatings. To clarify the situation and distinguish products from each other, a special symbol is used on the packaging labels
for RoHS compatible capacitors.
Because of customer requirements, there may appear additional markings such as LF = Lead Free or LFW = Lead Free Wires
on the label.
7© KEMET Electronics Corporation • P.O. Box 5928 • Greenville, SC 29606 • 864-963-6300 • www.kemet.com A4024_PEH534 • 2/7/2017
Snap-In Aluminum Electrolytic Capacitors – PEH534, +105°C
Table 1 – Ratings & Part Number Reference
(1) Termination code: See Termination Tables for available options.
VDC
Rated
Capacitance Size Code Case Size Ripple Current
Maximum ESR Maximum Part Number
100 Hz
20°C (µF)
D x L (mm)
100 Hz
105°C (A)
20 kHz
40°C (A)
100 Hz
20°C (mΩ)
100 kHz
20°C (mΩ)
35 5600 BC 25 x 30 2.3 7.6 54 43 PEH534JBC4560M(1)
35 6800 BD 25 x 35 2.7 9.0 43 34 PEH534JBD4680M(1)
35 6800 CB 30 x 25 2.9 9.8 40 31 PEH534JCB4680M(1)
35 8200 BE 25 x 40 3.1 10.2 36 28 PEH534JBE4820M(1)
35 8200 CC 30 x 30 3.5 12.1 31 23 PEH534JCC4820M(1)
35 8200 DB 35 x 25 3.1 10.0 37 29 PEH534JDB4820M(1)
35 10000 BF 25 x 45 3.5 11.3 31 24 PEH534JBF5100M(1)
35 10000 CD 30 x 35 4.1 14.3 25 18 PEH534JCD5100M(1)
35 15000 CF 30 x 45 5.3 17.8 17 13 PEH534JCF5150M(1)
35 15000 DD 35 x 35 4.5 14.4 21 17 PEH534JDD5150M(1)
35 22000 DG 35 x 50 6.2 20.1 14 11 PEH534JDG5220M(1)
63 2200 BC 25 x 30 1.9 6.9 92 43 PEH534MBC4220M(1)
63 3300 BE 25 x 40 2.5 9.3 61 34 PEH534MBE4330M(1)
63 3300 CC 30 x 30 2.7 10.6 56 31 PEH534MCC4330M(1)
63 4700 CE 30 x 40 3.6 14.0 39 28 PEH534MCE4470M(1)
63 4700 DC 35 x 30 3.1 11.2 44 23 PEH534MDC4470M(1)
63 5600 CF 30 x 45 4.0 15.6 33 29 PEH534MCF4560M(1)
63 5600 DD 35 x 35 3.7 13.3 36 24 PEH534MDD4560M(1)
63 6800 CG 30 x 50 4.5 17.1 28 18 PEH534MCG4680M(1)
63 6800 DE 35 x 40 4.2 15.2 30 13 PEH534MDE4680M(1)
63 8200 DF 35 x 45 4.7 16.8 26 17 PEH534MDF4820M(1)
63 10000 DG 35 x 50 5.2 18.4 22 11 PEH534MDG5100M(1)
100 1500 BE 25 x 40 1.9 7.0 140 110 PEH534PBE4150M(1)
100 1500 CC 30 x 30 2.0 7.4 130 100 PEH534PCC4150M(1)
100 2200 CE 30 x 40 2.6 9.8 91 70 PEH534PCE4220M(1)
100 2200 DC 35 x 30 2.4 8.8 96 75 PEH534PDC4220M(1)
100 3300 CG 30 x 50 3.3 12.4 62 48 PEH534PCG4330M(1)
100 3300 DE 35 x 40 3.3 11.7 64 50 PEH534PDE4330M(1)
100 3900 DF 35 x 45 3.6 13.1 54 43 PEH534PDF4390M(1)
100 4700 DG 35 x 50 4.1 14.5 46 36 PEH534PDG4470M(1)
200 470 BD 25 x 35 1.1 7.1 290 160 PEH534RBD3470M(1)
200 560 BE 25 x 40 1.3 8.0 250 130 PEH534RBE3560M(1)
200 560 CC 30 x 30 1.3 8.9 240 130 PEH534RCC3560M(1)
200 680 BF 25 x 45 1.4 8.9 200 110 PEH534RBF3680M(1)
200 680 CD 30 x 35 1.5 10.4 200 100 PEH534RCD3680M(1)
200 680 DC 35 x 30 1.5 9.8 200 110 PEH534RDC3680M(1)
200 820 CE 30 x 40 1.7 11.8 160 87 PEH534RCE3820M(1)
200 820 DC 35 x 30 1.6 9.8 170 93 PEH534RDC3820M(1)
200 1000 CG 30 x 50 2.0 13.9 130 71 PEH534RCG4100M(1)
200 1000 DD 35 x 35 1.9 11.6 140 75 PEH534RDD4100M(1)
200 1500 DF 35 x 45 2.5 14.7 93 51 PEH534RDF4150M(1)
250 390 BE 25 x 40 1.1 7.9 290 140 PEH534SBE3390M(1)
250 390 CC 30 x 30 1.1 8.7 280 140 PEH534SCC3390M(1)
250 470 BF 25 x 45 1.3 8.8 240 120 PEH534SBF3470M(1)
250 470 CD 30 x 35 1.3 10.1 240 110 PEH534SCD3470M(1)
250 470 DC 35 x 30 1.3 9.6 240 120 PEH534SDC3470M(1)
250 560 BG 25 x 50 1.4 9.6 200 100 PEH534SBG3560M(1)
250 560 CE 30 x 40 1.5 11.4 200 95 PEH534SCE3560M(1)
250 680 CF 30 x 45 1.7 12.8 160 79 PEH534SCF3680M(1)
250 680 DD 35 x 35 1.7 11.5 170 83 PEH534SDD3680M(1)
250 820 CG 30 x 50 1.9 14.2 140 66 PEH534SCG3820M(1)
250 820 DE 35 x 40 1.9 13.1 140 69 PEH534SDE3820M(1)
250 1000 DF 35 x 45 2.2 14.6 110 57 PEH534SDF4100M(1)
350 220 BE 25 x 40 0.9 5.8 560 350 PEH534UBE3220M(1)
350 220 CC 30 x 30 0.9 6.0 550 340 PEH534UCC3220M(1)
350 220 DB 35 x 25 0.9 5.8 560 350 PEH534UDB3220M(1)
350 330 CE 30 x 40 1.2 8.0 370 230 PEH534UCE3330M(1)
350 330 DC 35 x 30 1.2 7.4 370 230 PEH534UDC3330M(1)
350 390 CF 30 x 45 1.4 9.0 310 190 PEH534UCF3390M(1)
350 390 DD 35 x 35 1.4 8.6 320 200 PEH534UDD3390M(1)
VDC Rated
Capacitance Size Code Case Size Ripple Current ESR Part Number
8© KEMET Electronics Corporation • P.O. Box 5928 • Greenville, SC 29606 • 864-963-6300 • www.kemet.com A4024_PEH534 • 2/7/2017
Snap-In Aluminum Electrolytic Capacitors – PEH534, +105°C
Table 1 – Ratings & Part Number Reference cont'd
(1) Termination code: See Termination Tables for available options.
Mechanical Data
The capacitor may be mounted in any position. PEH534 is supplied with an insulation sleeve. Voltage proof of the insulation
sleeve = 2.5 kVDC (1 min). The minus pole is marked on the case surface. UL recognized sleeving is available for custom
parts in this range, upon request. (UL No. E358957)
VDC
Rated
Capacitance Size Code Case Size Ripple Current
Maximum ESR Maximum Part Number
100 Hz
20°C (µF)
D x L (mm)
100 Hz
105°C (A)
20 kHz
40°C (A)
100 Hz
20°C (mΩ)
100 kHz
20°C (mΩ)
350 470 DE 35 x 40 1.6 9.7 260 160 PEH534UDE3470M(1)
350 560 DF 35 x 45 1.8 10.9 220 140 PEH534UDF3560M(1)
400 150 BD 25 x 35 0.8 5.1 680 410 PEH534VBD3150M(1)
400 150 CB 30 x 25 0.8 5.2 680 400 PEH534VCB3150M(1)
400 220 BF 25 x 45 1.0 6.5 470 280 PEH534VBF3220M(1)
400 220 CD 30 x 35 1.0 7.1 460 270 PEH534VCD3220M(1)
400 220 DC 35 x 30 1.1 7.0 460 280 PEH534VDC3220M(1)
400 330 CF 30 x 45 1.4 9.2 310 180 PEH534VCF3330M(1)
400 330 DD 35 x 35 1.4 8.7 310 190 PEH534VDD3330M(1)
400 390 CG 30 x 50 1.5 10.2 260 160 PEH534VCG3390M(1)
400 390 DE 35 x 40 1.5 9.8 260 160 PEH534VDE3390M(1)
400 470 DF 35 x 45 1.8 11.1 220 130 PEH534VDF3470M(1)
400 560 DG 35 x 50 2.0 12.3 180 110 PEH534VDG3560M(1)
450 150 BE 25 x 40 0.9 5.8 570 330 PEH534YBE3150M(1)
450 150 CC 30 x 30 0.9 6.1 560 330 PEH534YCC3150M(1)
450 150 DB 35 x 25 0.9 5.9 570 330 PEH534YDB3150M(1)
450 220 CE 30 x 40 1.2 8.1 380 220 PEH534YCE3220M(1)
450 220 DC 35 x 30 1.2 7.5 390 230 PEH534YDC3220M(1)
450 330 CG 30 x 50 1.5 10.3 260 150 PEH534YCG3330M(1)
450 330 DE 35 x 40 1.5 9.9 260 150 PEH534YDE3330M(1)
450 390 DF 35 x 45 1.7 11.3 220 130 PEH534YDF3390M(1)
450 470 DG 35 x 50 1.9 12.4 180 110 PEH534YDG3470M(1)
VDC Rated
Capacitance Size Code Case Size Ripple Current ESR Part Number
9© KEMET Electronics Corporation • P.O. Box 5928 • Greenville, SC 29606 • 864-963-6300 • www.kemet.com A4024_PEH534 • 2/7/2017
Snap-In Aluminum Electrolytic Capacitors – PEH534, +105°C
Marking
KEMET Logo
Rated Capacitance,
Rated Voltage (VDC)
Part Number Code
Operating Temperature
Date of Manufacture,
Batch Number
Polarity Stripe ()
(Not Shown)
Construction
Detailed Cross Section
Termination Pin (+)
Rubber Seal
Rubber Seal
Insulating Sleeve Aluminum Can
with Safety Vent
Laser Welded
Terminal Tabs
Polarity Stripe ()
(Not Shown)
Insulating End Disc
Termination Pin ()
Paper Spacer Impregnated
with Electrolyte
(First Layer)
Paper Spacer Impregnated
with Electrolyte
(Third Layer)
Anode Aluminum Foil, Etched,
Covered with Aluminum Oxide
(Fourth Layer)
Cathode Aluminum Foil,
Etched (Second Layer)
Margin
Termination Pin
Laser Welded
Terminal Tab
Aluminum Can
Insulating Sleeve
10© KEMET Electronics Corporation • P.O. Box 5928 • Greenville, SC 29606 • 864-963-6300 • www.kemet.com A4024_PEH534 • 2/7/2017
Snap-In Aluminum Electrolytic Capacitors – PEH534, +105°C
Construction Data
The manufacturing process begins with the anode foil being
electrochemically etched to increase the surface area and
then “formed” to produce the aluminum oxide layer. Both the
anode and cathode foils are then interleaved with absorbent
paper and wound into a cylinder. During the winding process,
aluminum tabs are attached to each foil to provide the
electrical contact.
The deck, complete with terminals, is attached to the tabs and
then folded down to rest on top of the winding. The complete
winding is impregnated with electrolyte before being housed
in a suitable container, usually an aluminum can, and sealed.
Throughout the process, all materials inside the housing must
be maintained at the highest purity and be compatible with the
electrolyte.
Each capacitor is aged and tested before being sleeved and
packed. The purpose of aging is to repair any damage in the
oxide layer and thus reduce the leakage current to a very low
level. Aging is normally carried out at the rated temperature
of the capacitor and is accomplished by applying voltage to
the device while carefully controlling the supply current. The
process may take several hours to complete.
Damage to the oxide layer can occur due to variety of reasons:
• Slitting of the anode foil after forming
• Attaching the tabs to the anode foil
• Minor mechanical damage caused during winding
A sample from each batch is taken by the quality department
after completion of the production process.
The following tests are applied and may be varied at the
request of the customer. In this case the batch, or special
procedure, will determine the course of action.
Electrical:
• Leakage current
• Capacitance
• ESR
• Impedance
• Tan Delta
Mechanical/Visual:
• Overall dimensions
Torque test of mounting stud
• Print detail
• Box labels
• Packaging, including
packed quantity
Extended cathode
Anode foil
Cathode foil
Tissues
Foil tabs
Aging
Etching
Forming
Winding
Decking
Impregnation
Assembly
Testing
Sleeving
Packing
11© KEMET Electronics Corporation • P.O. Box 5928 • Greenville, SC 29606 • 864-963-6300 • www.kemet.com A4024_PEH534 • 2/7/2017
Snap-In Aluminum Electrolytic Capacitors – PEH534, +105°C
KEMET Electronic Corporation Sales Of ces
For a complete list of our global sales of ces, please visit www.kemet.com/sales.
Disclaimer
All product speci cations, statements, information and data (collectively, the “Information”) in this datasheet are subject to change. The customer is responsible for
checking and verifying the extent to which the Information contained in this publication is applicable to an order at the time the order is placed.
All Information given herein is believed to be accurate and reliable, but it is presented without guarantee, warranty, or responsibility of any kind, expressed or implied.
Statements of suitability for certain applications are based on KEMET Electronics Corporation’s (“KEMET) knowledge of typical operating conditions for such
applications, but are not intended to constitute – and KEMET speci cally disclaims – any warranty concerning suitability for a speci c customer application or use.
The Information is intended for use only by customers who have the requisite experience and capability to determine the correct products for their application. Any
technical advice inferred from this Information or otherwise provided by KEMET with reference to the use of KEMET’s products is given gratis, and KEMET assumes no
obligation or liability for the advice given or results obtained.
Although KEMET designs and manufactures its products to the most stringent quality and safety standards, given the current state of the art, isolated component
failures may still occur. Accordingly, customer applications which require a high degree of reliability or safety should employ suitable designs or other safeguards
(such as installation of protective circuitry or redundancies) in order to ensure that the failure of an electrical component does not result in a risk of personal injury or
property damage.
Although all product–related warnings, cautions and notes must be observed, the customer should not assume that all safety measures are indicted or that other
measures may not be required.
KEMET is a registered trademark of KEMET Electronics Corporation.
Mouser Electronics
Authorized Distributor
Click to View Pricing, Inventory, Delivery & Lifecycle Information:
Kemet:
PEH534JCD5100M2 PEH534RBD3470M2 PEH534RCD3680M2 PEH534RDD4100M2 PEH534RDF4150M2
PEH534SBE3390M2 PEH534SCD3470M2 PEH534SCE3560M2 PEH534SCF3680M2 PEH534SDF4100M2
PEH534VCB3150M2 PEH534VCD3220M2 PEH534VDC3220M2 PEH534VCF3330M2 PEH534VDF3470M2
PEH534VDG3560M2 PEH534YDB3150M2 PEH534YDC3220M2 PEH534YDE3330M2 PEH534YDG3470M2
PEH534SDF4100M2S PEH534YDF3390M2S