# TVS Diode, Transil SM4TY, Bidirectional, 18 V, 39.3 V, DO-214AC (SMA), 2 Pins
**URL**: https://novapart.co/products/SM4T21CAY/tvs-diode-transil-sm4ty-bidirectional-18-v-393-do
**SKU**: SM4T21CAY
**Manufacturer**: STMICROELECTRONICS
**Category**: Circuit Protection || TVS - Transient Voltage Suppressors || TVS Diodes
**Price**: €0.3130
**Stock**: 1000+
**Lead Time**: 127 days (indicative)
## Description
Product Range:Transil SM4TY Series; TVS Polarity:Bidirectional; Reverse Stand-Off Voltage Vrwm:18V; Clamping Voltage Vc Max:39.3V; Diode Case Style:DO-214AC; No. of Pins:2Pins; Breakdown V
## Specifications
| Parameter | Value |
|---|---|
| Svhc | No SVHC (25-Jun-2025) |
| No. Of Pins | 2Pins |
| Tvs Polarity | Bidirectional |
| Product Range | Transil SM4TY |
| Qualification | AEC-Q101 |
| Diode Mounting | Surface Mount |
| Diode Case Style | DO-214AC (SMA) |
| Clamping Voltage Max | 39.3V |
| Reverse Standoff Voltage | 18V |
| Maximum Breakdown Voltage | 22.2V |
| Minimum Breakdown Voltage | 20V |
| Operating Temperature Max | 150°C |
| Peak Pulse Power Dissipation | 400W |
## Datasheet
📄 [Download PDF](https://novapart.co/datasheet/farnell:2327868/)
## **SM4TY**
## Automotive 400 W Transil™
**Datasheet** - **production data**
## **Complies with the following standards**
**==> picture [143 x 107] intentionally omitted <==**
**----- Start of picture text -----**
A
K Sa
Unidirectional Bidirectional
SMA
(JEDEC DO-214AC)
**----- End of picture text -----**
- ISO 10605, C = 150 pF, R = 330 Ω:
- 30 kV (air discharge)
- 30 kV (contact discharge)
- ISO 10605, C = 330 pF, R = 330 Ω:
- 30 kV (air discharge)
- 30 kV (contact discharge)
- ISO 7637-2[(a)]
- pulse 1: VS = -100 V
- pulse 2a: VS = +50 V
- pulse 3a: VS = -150 V
- pulse 3b: VS = +100 V
## **Features**
- Peak pulse power:
- 400 W (10/1000 µs) 2.3 kW (8/20 µs)
-
-
- Stand-off voltage range: from 5 V to 70 V
- Unidirectional and bidirectional types
- Low leakage current:
- 0.2 µA at 25 °C
- 1 µA at 85 °C
- Operating Tj max: 150 °C
## **Description**
The SM4TY Transil series has been designed to protect sensitive automotive circuits against surges defined in ISO 7637-2 and against electrostatic discharges according to ISO 10605.
The planar technology makes it compatible with high-end circuits where low leakage current and high junction temperature are required to provide reliability and stability over time. SM4TY devices are packaged in SMA (SMA footprint in accordance with IPC 7531 standard).
- High power capability at Tjmax:
- 270 W (10/1000 µs)
- JEDEC registered package outline
- Resin meets UL 94, V0
- AEC-Q101 qualified
**TM** : Transil is a trademark of STMicroelectronics
- a. Not applicable to parts with stand-off voltage lower than the average battery voltage (13.5 V)
October 2015
DocID17862 Rev 4
1/12
This is information on a product in full production.
_www.st.com_
**Characteristics**
**SM4TY**
## **1 Characteristics**
**Table 1. Absolute maximum ratings (Tamb = 25** °C **)**
||**Table 1. Absolute maximum ratings (Tamb = 25**°C**)**|**Table 1. Absolute maximum ratings (Tamb = 25**°C**)**|**Table 1. Absolute maximum ratings (Tamb = 25**°C**)**|||
|---|---|---|---|---|---|
|**Symbol**|**Parameter**|||**Value**|**Unit**|
|VPP|Peak pulse voltage|ISO 10605 (C = 150 pF, R = 330Ω)
Contact discharge
Air discharge||30
30|kV|
|||ISO 10605, C = 330 pF, R = 330Ω:
Contact discharge
Air discharge||30
30||
|PPP|Peak pulse power dissipation(1)||Tj initial= Tamb|400|W|
|Tstg|Storage temperature range|||-65 to + 150|°C|
|Tj|Operating junction temperature range|||-55 to + 150|°C|
|TL|Maximum lead temperature for soldering during 10 s.|||260|°C|
1. For a surge greater than the maximum values, the diode will fail in short-circuit.
**Figure 1. Electrical characteristics - definitions**
**==> picture [461 x 282] intentionally omitted <==**
**----- Start of picture text -----**
I I
Symbol VRM Stand-off voltage Parameter Unidirectional IF IPP
VBR Breakdown voltage
VIRMCL Leakage current @ VClamping voltage RM VCLVBR VRM VF V VCLVBR VRM IIRMR V
IαPPT Peak pulse currentVoltage temperature coefficient IRMIR IRMIR VRMVBR VCL
VF Forward voltage drop
RD Dynamic resistance IPP IPP Bidirectional
Figure 2. Pulse definition for electrical characteristics
%IPP
100
Pulse waveform
50 tr = rise time (µs)
tp = pulse duration time (µs)
0 t
tr tp
**----- End of picture text -----**
2/12
DocID17862 Rev 4
**SM4TY**
**Characteristics**
**Table 2. Electrical characteristics, typical values if not otherwise stated (Tamb = 25 °C)**
|**Order code**|**IRM max @ VRM**|**IRM max @ VRM**|**IRM max @ VRM**|**VBR @ IR (1)**|**VBR @ IR (1)**|**VBR @ IR (1)**|**VBR @ IR (1)**|**VCL @ IPP**
**10/1000 µs**|**VCL @ IPP**
**10/1000 µs**|**RD**
**10/1000**
**µs**|**VCL @ IPP**
**8/20 µs**|**VCL @ IPP**
**8/20 µs**|**RD**
**8/20**
**µs**|α**T(2)**|
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
||**25 °C **|**85 °C**||**min.**|**typ.**|**max.**||**max.**|||**max.**|||**max**|
||**µA**||**V**|**V**|||**mA**|**V(3)**|**A(4)**|Ω|**V(3)**|**A(4)**|Ω|**10-4/**
**°C**|
|SM4T6V7AY/CAY|20|50|5|6.4|6.74|7.1|10|9.2|43.5|0.049|13.4|174|0.036|5.7|
|SM4T7V6AY/CAY|20|50|6.5|7.2|7.58|8.0|10|11.2|35.7|0.091|14.5|160|0.041|6.1|
|SM4T10AY/CAY|20|50|8.5|9.4|9.9|10.4|1|14.4|27.7|0.145|19.5|124|0.073|7.3|
|SM4T12AY/CAY|0.2|1|10|11.1|11.7|12.3|1|17.0|23.5|0.201|21.7|106|0.089|7.8|
|SM4T14AY/CAY|0.2|1|12|13.3|14.0|14.7|1|19.9|20.1|0.259|25.3|91|0.116|8.3|
|SM4T15AY/CAY|0.2|1|13|14.4|15.2|16.0|1|21.5|18.6|0.298|27.2|85|0.132|8.4|
|SM4T18AY/CAY|0.2|1|15|16.7|17.6|18.5|1|24.4|16.4|0.361|32.5|71|0.197|8.8|
|SM4T21AY/CAY|0.2|1|18|20.0|21.1|22.2|1|29.2|13.7|0.514|39.3|59|0.291|9.2|
|SM4T23AY/CAY|0.2|1|20|22.2|23.4|24.6|1|32.4|12.3|0.637|42.8|54|0.338|9.4|
|SM4T26AY/CAY|0.2|1|22|24.4|25.7|27.0|1|35.5|11.2|0.760|48.3|48|0.444|9.6|
|SM4T28AY/CAY|0.2|1|24|26.7|28.1|29.5|1|38.9|10.3|0.912|50|46|0.446|9.6|
|SM4T30AY/CAY|0.2|1|26|28.9|30.4|31.9|1|42.1|9.5|1.07|53.5|43|0.502|9.7|
|SM4T33AY/CAY|0.2|1|28|31.1|32.7|34.3|1|45.4|8.8|1.26|59|39|0.632|9.8|
|SM4T35AY/CAY|0.2|1|30|33.3|35.1|36.9|1|48.4|8.3|1.39|64.3|36|0.762|9.9|
|SM4T39AY/CAY|0.2|1|33|36.7|38.6|40.5|1|53.3|7.5|1.70|69.7|33|0.884|10|
|SM4T47AY/CAY|0.2|1|40|44.4|46.7|49.0|1|64.5|6.2|2.49|84|27|1.30|10.1|
|SM4T50AY/CAY|0.2|1|43|47.8|50.3|52.8|1|69.4|5.7|2.91|91|25|1.53|10.2|
|SM4T56AY/CAY|0.2|1|48|53.3|56.1|58.9|1|77.4|5.2|3.56|100|23|1.79|10.3|
|SM4T68AY/CAY|0.2|1|58|64.4|67.8|71.2|1|93.6|4.3|5.21|121|19|2.62|10.4|
|SM4T82AY/CAY|0.2|1|70|77.8|81.9|86.0|1|113|3.5|7.72|146|16|3.75|10.5|
1. Pulse test: t < 50 ms p
2. To calculate maximum clamping voltage at other surge level, use the following formula: VCLmax = VCL - RD x (IPP - IPPappli) where IPPappli is the surge current in the application
3. To calculate VBR or VCL versus junction temperature, use the following formulas: VBR @ TJ = VBR @ 25 °C x (1 + α T x (TJ - 25)) VCL @ TJ = VCL @ 25 °C x (1 + α T x (TJ - 25))
4. Surge capability given for both directions for unidirectional and bidirectional types.
DocID17862 Rev 4
3/12
**Characteristics**
**SM4TY**
**==> picture [462 x 182] intentionally omitted <==**
**----- Start of picture text -----**
Figure 3. Peak pulse power dissipation versus Figure 4. Peak pulse power versus exponential
initial junction temperature pulse duration
(Tj initial = 25 °C)
500 PPP(W) 10.0 PPP(kW)
Pulse = 10/1000 µs
400
300
1.0
200
100
0 T (°C)j 0.1 tp(ms)
0 25 50 75 100 125 150 175 1.0E-03 1.0E-02 1.0E-01 1.0E+00 1.0E+01
**----- End of picture text -----**
**Figure 5. Clamping voltage versus peak pulse current (exponential waveform, maximum values)**
**Figure 6. Junction capacitance versus reverse applied voltage for unidirectional types (typical values)**
**==> picture [462 x 360] intentionally omitted <==**
**----- Start of picture text -----**
1000.0 IPP(A) 10000 C(pF)
T initial = 25 °Cj F = 1 Mhz
V OSC = 30 mV RMS
100.0 T j = 25 °C
SM4T6V7AY
1000
8/20 µs
10.0
10/1000 µs SM4T30AY
100
1.0
SM4T82AY
0.1 VCL(V) 10 VR(V)
1 10 100 1000 1 10 100 1000
Figure 7. Junction capacitance versus reverse Figure 8. Relative variation of thermal
applied voltage for bidirectional types (typical impedance, junction to ambient, versus pulse
values) duration
10000 C(pF) Zth(j-a)/Rth(j-a)
F = 1 Mhz 1.00
VOSCT j = 30 mV= 25 °C RMS Recommended pad layout Printed circuit board FR4,copper thickness = 35 µm
1000 SM4T6V7CAY
0.10
SM4T30CAY
100
SM4T82CAY
10 VR(V) 0.01 tp(s)
1 10 100 1000 1.0E-03 1.0E-02 1.0E-01 1.0E+00 1.0E+01 1.0E+02 1.0E+03
SM4T6V7AY/CAY SM4T30AY/CAY SM4T82AY/CAY
**----- End of picture text -----**
4/12
DocID17862 Rev 4
**SM4TY**
**Characteristics**
**Figure 9. Thermal resistance junction to ambient versus copper surface under each lead**
**Figure 10. Leakage current versus junction temperature (typical values)**
**==> picture [462 x 313] intentionally omitted <==**
**----- Start of picture text -----**
130 Rth(j-a)(°C/W) 1.E+03 IR(nA)
120 Printed circuit board FR4,
110 copper thickness = 35 µm
100 1.E+02 VR = VRM
90 VRM < 10 V
80
70
1.E+01
60
50
40
30 1.E+00 V R = V RM
VRM [≥] 10 V
20
100 S Cu (cm²) 1.E-01 T (°C)j
0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 25 50 75 100 125 150
Figure 11. Peak forward voltage drop versus peak forward current (typical values)
IFM(A)
1.0E+02
1.0E+01
T j = 125 °C
1.0E+00
Tj = 25 °C
1.0E-01
VFM(V)
1.0E-02
0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5
**----- End of picture text -----**
DocID17862 Rev 4
5/12
**Characteristics**
**SM4TY**
**Figure 12. ISO7637-2 pulse 1 response (VS = -100 V)**
**==> picture [285 x 264] intentionally omitted <==**
**----- Start of picture text -----**
Voltage (V)
Voltage
10
0
-10
-20
-30
SM4T39AY
-40
SM4T39CAY
-50
-0.5 0.0 0.5 1.0 1.5 2.0 2.5
Time (ms)
5 Current (A)
Current
0
SM4T39AY
0.0
SM4T39CAY
-10
-15
-0.5 0.0 0.5 1.0 1.5 2.0 2.5
Time (ms)
**----- End of picture text -----**
**Figure 13. ISO7637-2 pulse 2a response (VS = 50 V)**
**==> picture [291 x 329] intentionally omitted <==**
**----- Start of picture text -----**
Voltage (V) Voltage
50
40
SM4T39AY
30
SM4T39CAY
20
10
0 —=
-51 -1 49 99 149 199 249
Time (µs)
Current (A)
4
Current
SM4T39AY
SM4T39CAY
0
-4 a
-51 -1 49 99 149 199 249
Time (µs)
DocID17862 Rev 4
**----- End of picture text -----**
6/12
**SM4TY**
**Characteristics**
**Figure 14. ISO7637-2 pulse 3a response (VS = -150 V)**
**==> picture [322 x 257] intentionally omitted <==**
**----- Start of picture text -----**
30 Voltage (V)
20 Voltage
10 SM4T39AY
0
SM4T39CAY
-10
-20
-30
-40
ml
-50
-60
-0.2 0.8 1.8 0.0 0.0 0.0
Time (µs)
0.5 Current (A)
-0.50 |iames Current
_ SM4T39AY
-1
-1.5 | SM4T39CAY
-2
-2.5
-0.2 0.8 1.8 0.0 0.0 0.0
Time (µs)
**----- End of picture text -----**
**Figure 15. ISO7637-2 pulse 3b response (VS = 100 V)**
**==> picture [322 x 256] intentionally omitted <==**
**----- Start of picture text -----**
50 Voltage (V)
Voltage
40
SM4T39AY
30
SM4T39CAY
20
10
0
-0.2 0.8 1.8
Time (µs)
1.2 Current (A)
Current
0.8
— SM4T39AY
0.4 |
SM4T39CAY
0.0
-0.4
-0.2 0.8 1.8
Time (µs)
**----- End of picture text -----**
_Note: ISO7637-2 pulses responses are not applicable for product with a stand off voltage lower than the average battery voltage (13.5 V)._
7/12 ~~a~~
DocID17862 Rev 4 7/12
**SM4TY**
**Application and design guidelines**
## **2 Application and design guidelines**
More information is available in the Application note AN2689 “Protection of automotive electronics from electrical hazards, guidelines for design and component selection”.
## **3 Ordering information scheme**
## **Figure 16. Ordering information scheme**
**==> picture [290 x 170] intentionally omitted <==**
**----- Start of picture text -----**
SM 4T XX CA Y
Surface mount
Surge rating
4 = 400 W Transil in SMA
Breakdown voltage
Type s
CA = Bidirectional
A = Unidirectional
Automotive grade
**----- End of picture text -----**
8/12
DocID17862 Rev 4
**SM4TY**
**Package information**
## **4 Package information**
- Case: JEDEC DO-214AB molded plastic over planar junction
- Terminals: solder plated, solderable as per MIL-STD-750, Method 2026
- Polarity: for unidirectional types the band indicates cathode
- Flammability: epoxy is rated UL 94, V0
- RoHS package
In order to meet environmental requirements, ST offers these devices in different grades of ECOPACK[®] packages, depending on their level of environmental compliance. ECOPACK[®] specifications, grade definitions and product status are available at: www.st.com. ECOPACK[®] is an ST trademark.
**Table 3. SMA package dimensions**
|**C**|||||||**b**|**b**|**b**|**Ref.**|**Dimensions**|**Dimensions**|**Dimensions**|**Dimensions**|
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
||||||||||||**Millimeters**||**Inches**||
|||**E1**|||**L**
**D**
**A1**
**A2**||||||**Min.**|**Max.**|**Min.**|**Max.**|
||||||||||||||||
||||||||||||||||
|||||||||||A1|1.90|2.45|0.075|0.094|
|||||||||||A2|0.05|0.20|0.002|0.008|
||||||||||||||||
|||**E**||||||||b|1.25|1.65|0.049|0.065|
|||||||||||c|0.15|0.40|0.006|0.016|
||||||||||||||||
|||||||||||D
|2.25
|2.90
|0.089
|0.114
|
||||||||||||||||
||||||**L**|||**b**||E|4.80|5.35|0.189|0.211|
|||||||||||E1|3.95|4.60|0.156|0.181|
|||||||||||L|0.75|1.50|0.030|0.059|
**Figure 17. SMA footprint dimensions in mm (inches)**
**Figure 18. Marking layout[(1)]**
**==> picture [405 x 146] intentionally omitted <==**
**----- Start of picture text -----**
1.4 2.63 1.4
(0.055) (0.104) (0.055) Cathode bar (unidirectional devices only)
ECOPACK compliance
1.64 XXXX: Marking
(0.064) x x x x Z:Y: ManufacturingYear location
WW: week
5.43 z y w w
(0.214)
**----- End of picture text -----**
1. Marking layout can vary according to assembly location.
DocID17862 Rev 4
9/12
**SM4TY**
**Package information**
**Table 4. Marking**
||**Table 4.**|**Marking**||
|---|---|---|---|
|**Order code**|**Marking**|**Order code**|**Marking**|
|SM4T6V7AY|AEY|SM4T6V7CAY|AAY|
|SM4T7V6AY|DUCY|SM4T7V5CAY|DBCY|
|SM4T10AY|DUHY|SM4T10CAY|DBHY|
|SM4T12AY|AXY|SM4T12CAY|ACY|
|SM4T14AY|DUKY|SM4T14CAY|DBKY|
|SM4T15AY|BGY|SM4T15CAY|BHY|
|SM4T18AY|BMY|SM4T18CAY|AJY|
|SM4T21AY|DUQY|SM4T21CAY|DBQY|
|SM4T23AY|DURY|SM4T23CAY|DBRY|
|SM4T26AY|DUSY|SM4T26CAY|DBSY|
|SM4T28AY|DUTY|SM4T28CAY|DBTY|
|SM4T30AY|DUUY|SM4T30CAY|DBUY|
|SM4T33AY|CGY|SM4T33CAY|CHY|
|SM4T35AY|CKY|SM4T35CAY|CLY|
|SM4T39AY|CMY|SM4T39CAY|CNY|
|SM4T47AY|DUZY|SM4T47CAY|DBZY|
|SM4T50AY|EUAY|SM4T50CAY|EBAY|
|SM4T56AY|CXY|SM4T56CAY|CYY|
|SM4T68AY|EUFY|SM4T68CAY|EBFY|
|SM4T82AY|EUIY|SM4T82CAY|EBIY|
10/12
DocID17862 Rev 4
**SM4TY**
**Ordering information**
## **5 Ordering information**
**Table 5. Ordering information**
|**Order code**|**Marking**|**Package**|**Weight**|**Base qty**|**Delivery mode**|
|---|---|---|---|---|---|
|SM4TxxxAY/CAY(1)|See_Table 4 on page 10_|SMA|0.072 g|5000|Tape and reel|
1. Where xxx is nominal value of VBR and A or CA indicates unidirectional or bidirectional version. See _Table 2_ for list of available devices and their order codes
## **6 Revision history**
**Table 6. Document revision history**
|**Date**|**Revision**|**Changes**|
|---|---|---|
|08-Sep-2010|1|Initial release.|
|09-Nov-2011|2|Added order codes in Table 2 and Table 4. Updated
Figure 5, 6 and 7.|
|27-Mar-2012|3|Added footnote on page 1.|
|05-Oct-2015|4|Updated_Table 1_.|
DocID17862 Rev 4
11/12
**SM4TY**
## **IMPORTANT NOTICE – PLEASE READ CAREFULLY**
STMicroelectronics NV and its subsidiaries (“ST”) reserve the right to make changes, corrections, enhancements, modifications, and improvements to ST products and/or to this document at any time without notice. Purchasers should obtain the latest relevant information on ST products before placing orders. ST products are sold pursuant to ST’s terms and conditions of sale in place at the time of order acknowledgement.
Purchasers are solely responsible for the choice, selection, and use of ST products and ST assumes no liability for application assistance or the design of Purchasers’ products.
No license, express or implied, to any intellectual property right is granted by ST herein.
Resale of ST products with provisions different from the information set forth herein shall void any warranty granted by ST for such product.
ST and the ST logo are trademarks of ST. All other product or service names are the property of their respective owners.
Information in this document supersedes and replaces information previously supplied in any prior versions of this document.
© 2015 STMicroelectronics – All rights reserved
12/12 DocID17862 Rev 4
## Links
- [View this product on Novapart](https://novapart.co/products/SM4T21CAY/tvs-diode-transil-sm4ty-bidirectional-18-v-393-do)
- [Request a quote for this part](https://novapart.co/quote/)
- [Supplier page](https://es.farnell.com/stmicroelectronics/sm4t21cay/diode-tvs-400w-21-1v-sma/dp/2327868)
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