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PSSI2021SAY,115
Bipolar (BJT) Single Transistor, Current Source, PNP
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- Manufacturer: NEXPERIA
- Product type:
- Forward Current If:-; Forward Voltage:-; Forward Current If(AV):-; Power Dissipation Pd:335mW; Current Regulator Case Style:SOT-353; No. of Pins:5 Pin; MSL:MSL 1 - Unlimited; SVHC:No
- MSL: MSL 1 - Unlimited
- SVHC: No SVHC (25-Jun-2025)
- No. of Pins: 5Pins
- Product Range: -
- Qualification: -
- IC Case / Package: SOT-353
- Transistor Polarity: PNP
- Power Dissipation Pd: 335mW
- Operating Temperature Max: 150°C
- Operating Temperature Range: -65°C to +150°C
- Current Regulator Case Style: SOT-353
| Delivery and price | |
|---|---|
| Units per pack | 9000 |
| Price | 0.146 € |
| Current stock | 1000+ |
| Lead time | 30 days |
Datasheet
**==> picture [47 x 51] intentionally omitted <==** ## **PSSI2021SAY** ## **Constant current source in SOT353 package** **Rev. 03 — 27 August 2009** ## **Product data sheet** ## **1.** ## **1.1 General description** Resistor-equipped PNP transistor with two diodes on one chip in a SOT353 (SC-88A) plastic package. Stabilized output current of between 15 µA and 50 mA by connection of an external resistor between pins 4 and 5. ## **1.2 Features** I One chip integrated constant current source - I Output current setting by use of an external resistor - I Very small package - I Reduces component count and board space ## **1.3 Applications** - I Automotive applications - I Generic constant current source - I Constant current LED driver - I ## **1.4 Quick reference data** |**Table 1.**|**Quick reference data**|||||| |---|---|---|---|---|---|---| |**Symbol**|**Parameter**|**Conditions**|**Min**|**Typ**|**Max**|**Unit**| |Iout|output current||0.015|-|50|mA| |VS|supply voltage||-|-|75|V| **==> picture [211 x 101] intentionally omitted <==** **PSSI2021SAY** **NXP Semiconductors** **Constant current source in SOT353 package** ## **2. Pinning information** **Table 2. Pinning** |**Pin**<br>**Symbol**<br>**Description**<br>**Simplifed outline**<br>**Symbol**|**Pin**<br>**Symbol**<br>**Description**<br>**Simplifed outline**<br>**Symbol**|**Pin**<br>**Symbol**<br>**Description**<br>**Simplifed outline**<br>**Symbol**| |---|---|---| |1<br>n.c.<br>not connected<br>2<br>IOUT<br>output current<br>3<br>GND<br>ground<br>4<br>REXT<br>external resistor<br>5<br>VS<br>supply voltage||1<br>3<br>2<br>4<br>5<br>1<br>n.c.<br>2<br>3<br>5<br>4<br>sym049| |||| |||| ## **3. Ordering information** **Table 3. Ordering information** |**Type number**|**Package**|**Package**|**Package**| |---|---|---|---| ||**Name**|**Description**|**Version**| |PSSI2021SAY|SC-88A<br>plastic surface mounted package; 5 leads<br>SOT353||| ## **4. Marking** ## **Table 4. Marking codes** |**Type number**|**Marking**|**cod**~~**e**~~<br>**[1]**| |---|---|---| |PSSI2021SAY|S1*|| - [1] * = -: made in Hong Kong - = t: made in Malaysia - = W: made in China © NXP B.V. 2009. All rights reserved. PSSI2021SAY_3 **Product data sheet** **Rev. 03 — 27 August 2009** **2 of 12** **PSSI2021SAY** **NXP Semiconductors** **Constant current source in SOT353 package** ## **5. Limiting values** ## **Table 5. Limiting values** In accordance with the Absolute Maximum Rating System (IEC 60134). |**Symbol**|**Parameter**|**Conditions**|**Conditions**|**Conditions**||**Min**|**Max**|**Unit**| |---|---|---|---|---|---|---|---|---| |Iout|stabilized output current|see|Figure|2||0.015|50|mA| |VS|supply voltage|||||-|75|V| |Vout|output voltage|VS= 75 V||||-|73|V| |VR|reverse voltage||||[1]|-|0.5|V| |Ptot|total power dissipation|Tamb≤25°C|||[2]|-|335|mW| |Tstg|storage temperature|||||−65|+150|°C| |Tj|junction temperature|||||-|150|°C| |Tamb|ambient temperature|||||−65|+150|°C| [1] Between all terminals [2] Device mounted on a FR4 printed-circuit board, single-sided copper, tin-plated, standard footprint ## **6. Thermal characteristics** |**Table 6.**|**Thermal characteristics**||||||| |---|---|---|---|---|---|---|---| |**Symbol**|**Parameter**|**Conditions**||**Min**|**Typ**|**Max**|**Unit**| |Rth(j-a)|thermal resistance from|in free air|[1]|-|-|370|K/W| ||junction to ambient||||||| [1] Device mounted on a FR4 printed-circuit board, single-sided copper, tin-plated, standard footprint ## **7. Characteristics** ## **Table 7. Characteristics** Tamb = 25 ° |**Symbol**<br>**Parameter**|**Conditions**<br>**Min**<br>**Typ**<br>**Max**<br>**Unit**| |---|---| |Iout<br>stabilized output current|VS= 12 V; Rext= open;<br>Vout= 0 V to 10 V;<br>see<br>Figure<br>2<br>10<br>15<br>20<br>µA| |IS<br>supply current|VS= 12 V; Iout= 15µA;<br>Vout= 0 V to 10 V;<br>see<br>Figure<br>4<br>-<br>240<br>370<br>µA| ||VS= 75 V; Iout= 15µA;<br>Vout= 0 V; see<br>Figure<br>4<br>-<br>1.5<br>2.2<br>mA| |∆Iout/ (Iout× ∆Tamb)<br>output current change over<br>ambient temperature|VS= 12 V; Vout= 1 V;<br>Tamb=−55°C to 150°C<br>-<br>0.15<br>-<br>%/K| |∆Iout/ Iout<br>load stability of stabilized<br>output current|VS=12 V;<br>Vout=1 V to 10 V<br>-<br>0.5<br>-<br>%| |Rint<br>internal resistor value|-<br>48<br>-<br>kΩ| © NXP B.V. 2009. All rights reserved. PSSI2021SAY_3 **Product data sheet** **Rev. 03 — 27 August 2009** **3 of 12** **PSSI2021SAY** **NXP Semiconductors** **Constant current source in SOT353 package** **==> picture [233 x 189] intentionally omitted <==** **----- Start of picture text -----**<br> 006aaa020<br>10 [[2]]<br>Ioutout<br>(mA) (1)<br>10 (2)<br>1 (3)<br>10 [[−][1]][[1]] (4)<br>(5)<br>(6)<br>10 [[−][2]][[2]]<br>10 10 [[2]] 10 [[3]] 10 [[4]]<br>RL (Ω)L (Ω) (Ω)Ω))<br>**----- End of picture text -----**<br> **==> picture [497 x 519] intentionally omitted <==** **----- Start of picture text -----**<br> 006aaa020 006aaa021<br>10 [[2]] 10 [2]<br>Ioutout Iout<br>(mA) (1) (mA) (1)<br>(2)<br>10 (2) 10<br>1 (3) 1 (3)<br>10 [[−][1]][[1]] (4) 10 [−][1] (4)<br>(5) (5)<br>(6) (6)<br>10 [[−][2]][[2]] 10 [−][2]<br>10 10 [[2]] 10 [[3]] 10 [[4]] 0 20 40 60 80<br>RL (Ω)L (Ω) (Ω)Ω)) VS (V)<br>VS = 12 V (1) Iout = 20 mA<br>(1) Iout = 20 mA (2) Iout = 10 mA<br>(2) Iout = 10 mA (3) Iout = 1mA<br>(3) Iout = 1mA (4) Iout = 100 µA<br>(4) Iout = 100 µA (5) Iout = 50 µA<br>(5) Iout = 50 µA (6) Iout = 15 µA<br>(6) Iout = 15 µA<br>Fig 1. Output current as a function of load Fig 2. Output current as a function of supply voltage;<br>resistance; typical values typical values<br>006aaa022 006aaa023<br>10 [2] 2.0<br>Iout IS<br>(mA) (mA)<br>10 1.5<br>1 1.0<br>10 [−][1] 0.5<br>10 [−][2] 0<br>10 10 [2] 10 [3] 10 [4] 10 [5] 10 [6] 0 20 40 60 80<br>Rext (Ω) VS (V)<br>**----- End of picture text -----**<br> VS = 12 V; RL = 100 Ω Rext = ∞; RL = 100 Ω **Fig 3. Output current as a function of external resistance; typical values** **Fig 4. Supply current as a function of supply voltage; typical values** © NXP B.V. 2009. All rights reserved. PSSI2021SAY_3 **Product data sheet** **Rev. 03 — 27 August 2009** **4 of 12** **PSSI2021SAY** **NXP Semiconductors** **Constant current source in SOT353 package** ## **8. Application information** ## **External resistor calculation** The output current can be set by connecting an external resistor between VS (pin 5) and REXT (pin 4). _0.617_ Iout then calculates to: _I out_ = ----------- _R_ **-** + _15_ µ _A ext_ Without an external resistor the output current will be typically 15 µA. ## **Typical output currents versus supply voltage VS** The applied supply voltage determines the output current. Table 8 gives typical Iout values at specified supply voltages, assuming that the working output current is 70% of the maximum possible output current. **Table 8.** |**VS (V)**|**Iout (mA)**| |---|---| |5|6| |12|18| |24|38| |36|60| © NXP B.V. 2009. All rights reserved. PSSI2021SAY_3 **Product data sheet** **Rev. 03 — 27 August 2009** **5 of 12** **PSSI2021SAY** **NXP Semiconductors** **Constant current source in SOT353 package** ## **8.1 Typical application circuits** ## **LED driver** Figure 5 shows a typical application circuit for an LED driver. The constant current ensures a constant LED brightness. **==> picture [94 x 125] intentionally omitted <==** **----- Start of picture text -----**<br> VS<br>VCC<br>Rext<br>REXT<br>IOUT<br>Iout<br>LED<br>GND<br>006aaa024<br>**----- End of picture text -----**<br> **Fig 5. LED driver application diagram** ## **Switching the current ON/OFF** The output can be switched ON and OFF by connecting a resistor-equipped transistor (RET, e.g. PDTC124XU) as shown in Figure 6. **==> picture [163 x 179] intentionally omitted <==** **----- Start of picture text -----**<br> VS<br>VCC<br>Rext<br>REXT<br>IOUT<br>GND Iout<br>OUT<br>IN/ LED<br>OUT<br>GND<br>006aaa025<br>**----- End of picture text -----**<br> **Fig 6. Switching the current ON/OFF; application diagram** © NXP B.V. 2009. All rights reserved. PSSI2021SAY_3 **Product data sheet** **Rev. 03 — 27 August 2009** **6 of 12** **PSSI2021SAY** **NXP Semiconductors** **Constant current source in SOT353 package** ## **Voltage reference** The PSSI2021SAY supplies a constant current to the Zener diode regardless of supply voltage variation, resulting in a constant reference voltage (see Figure 7). **==> picture [102 x 125] intentionally omitted <==** **----- Start of picture text -----**<br> VS<br>VCC<br>Rext<br>REXT<br>IOUT<br>Iout Vref<br>GND<br>006aaa026<br>**----- End of picture text -----**<br> **Fig 7. Voltage reference application diagram** © NXP B.V. 2009. All rights reserved. PSSI2021SAY_3 **Product data sheet** **Rev. 03 — 27 August 2009** **7 of 12** **PSSI2021SAY** **NXP Semiconductors** **Constant current source in SOT353 package** ## **9. Package outline** ## **Plastic surface-mounted package; 5 leads** **SOT353** **==> picture [478 x 569] intentionally omitted <==** **----- Start of picture text -----**<br> D B E A X<br>y HE v M A<br>5 4<br>Q<br>A<br>A1<br>1 2 3 c<br>e1 bp w M B Lp<br>e<br>detail X<br>0 1 2 mm<br>scale<br>DIMENSIONS (mm are the original dimensions)<br>A1<br>UNIT A max bp c D E [(2)] e e1 HE Lp Q v w y<br>1.1 0.3 0.25 2.2 1.35 2.2 0.45 0.25<br>mm 0.1 1.3 0.65 0.2 0.2 0.1<br>0.8 0.2 0.10 1.8 1.15 2.0 0.15 0.15<br>OUTLINE REFERENCES EUROPEAN<br>ISSUE DATE<br>VERSION IEC JEDEC JEITA PROJECTION<br>04-11-16<br> SOT353 SC-88A<br>06-03-16<br>**----- End of picture text -----**<br> ## **Fig 8. Package outline SOT353 (SC-88A)** © NXP B.V. 2009. All rights reserved. PSSI2021SAY_3 **Product data sheet** **Rev. 03 — 27 August 2009** **8 of 12** **PSSI2021SAY** **NXP Semiconductors** **Constant current source in SOT353 package** ## **10. Packing information** ## **Table 9. Packing methods** The indicated -xxx are the last three digits of the 12NC ordering code ~~.~~ [1] |**Type number**<br>**Package**<br>**Description**|**Packing quantity**| |---|---| ||**3000**| |PSSI2021SAY<br>SOT353<br>4 mm pitch, 8 mm tape and reel|-115| [1] For further information and the availability of packing methods, see Section 13. © NXP B.V. 2009. All rights reserved. PSSI2021SAY_3 **Product data sheet** **Rev. 03 — 27 August 2009** **9 of 12** **PSSI2021SAY** **NXP Semiconductors** **Constant current source in SOT353 package** ## **11. Revision history** ## **Table 10. Revision history** |**Document ID**|**Release date**<br>**Data sheet status**<br>**Change notice**||**Supersedes**| |---|---|---|---| |PSSI2021SAY_3|20090827<br>Product data sheet<br>-||PSSI2021SAY_2| |Modifcations:|**•** This data sheet was changed to refect the new company name NXP Semiconductors,<br>including new legal defnitions and disclaimers. No changes were made to the technical||| ||content.||| ||**•**<br>T<br>ab<br>le2 “Pinning”: amended||| ||**•**<br>Figure 8“P<br>ac<br>kage outline SO<br>T353 (SC-88A)”: updated||| |PSSI2021SAY_2|20041020<br>Product data sheet<br>-||PSSI2021SAY_1| |PSSI2021SAY_1|20010507<br>Product specifcation<br>-||-| © NXP B.V. 2009. All rights reserved. PSSI2021SAY_3 **Product data sheet** **Rev. 03 — 27 August 2009** **10 of 12** **PSSI2021SAY** **NXP Semiconductors** **Constant current source in SOT353 package** ## **12. Legal information** ## **12.1 Data sheet status** |**Document statu**|**s**<br>**[1]**<br>**[2]**<br>**Product status**<br>**[3]**<br>**Defnition**| |---|---| |Objective [short] data sheet<br>Development<br>This document contains data from the objective specifcation for product development.|| |Preliminary [short] data sheet<br>Qualifcation<br>This document contains data from the preliminary specifcation.|| |Product [short] data sheet<br>Production<br>This document contains the product specifcation.|| [1] Please consult the most recently issued document before initiating or completing a design. [2] [3] The product status of device(s) described in this document may have changed since this document was published and may differ in case of multiple devices. The latest product status information is available on the Internet at URL http://www.nxp.com. ## **12.2** **Draft —** The document is a draft version only. The content is still under internal review and subject to formal approval, which may result in modifications or additions. NXP Semiconductors does not give any representations or warranties as to the accuracy or completeness of information included herein and shall have no liability for the consequences of use of such information. **Short data sheet —** A short data sheet is an extract from a full data sheet with the same product type number(s) and title. A short data sheet is intended for quick reference only and should not be relied upon to contain detailed and full information. For detailed and full information see the relevant full data sheet, which is available on request via the local NXP Semiconductors sales office. In case of any inconsistency or conflict with the short data sheet, the full data sheet shall prevail. ## **12.3 Disclaimers** **General —** Information in this document is believed to be accurate and reliable. However, NXP Semiconductors does not give any representations or warranties, expressed or implied, as to the accuracy or completeness of such information and shall have no liability for the consequences of use of such information. **Right to make changes —** NXP Semiconductors reserves the right to make changes to information published in this document, including without limitation specifications and product descriptions, at any time and without notice. This document supersedes and replaces all information supplied prior to the publication hereof. **Suitability for use —** NXP Semiconductors products are not designed, authorized or warranted to be suitable for use in medical, military, aircraft, space or life support equipment, nor in applications where failure or malfunction of an NXP Semiconductors product can reasonably be expected to result in personal injury, death or severe property or environmental damage. NXP Semiconductors accepts no liability for inclusion and/or use of NXP Semiconductors products in such equipment or applications and therefore such inclusion and/or use is at the customer’s own risk. **Applications —** Applications that are described herein for any of these products are for illustrative purposes only. NXP Semiconductors makes no representation or warranty that such applications will be suitable for the specified use without further testing or modification. **Limiting values —** the Absolute Maximum Ratings System of IEC 60134) may cause permanent damage to the device. Limiting values are stress ratings only and operation of the device at these or any other conditions above those given in the Characteristics sections of this document is not implied. Exposure to limiting values for extended periods may affect device reliability. **Terms and conditions of sale —** NXP Semiconductors products are sold subject to the general terms and conditions of commercial sale, as published at http://www.nxp.com/profile/terms, including those pertaining to warranty, intellectual property rights infringement and limitation of liability, unless explicitly otherwise agreed to in writing by NXP Semiconductors. In case of any inconsistency or conflict between information in this document and such terms and conditions, the latter will prevail. **No offer to sell or license —** Nothing in this document may be interpreted or construed as an offer to sell products that is open for acceptance or the grant, conveyance or implication of any license under any copyrights, patents or other industrial or intellectual property rights. **Export control —** This document as well as the item(s) described herein may be subject to export control regulations. Export might require a prior authorization from national authorities. **Quick reference data —** The Quick reference data is an extract of the product data given in the Limiting values and Characteristics sections of this document, and as such is not complete, exhaustive or legally binding. ## **12.4 Trademarks** Notice: All referenced brands, product names, service names and trademarks are the property of their respective owners. ## **13. Contact information** For more information, please visit: **http://www.nxp.com** **salesaddresses@nxp.com** © NXP B.V. 2009. All rights reserved. PSSI2021SAY_3 **Product data sheet** **Rev. 03 — 27 August 2009** **11 of 12** **PSSI2021SAY** **NXP Semiconductors** **Constant current source in SOT353 package** ## **14. Contents** |**1**|**Product profle . . . . . . . . . . . . . . . . . . . . . . . . . . 1**| |---|---| |1.1|General description. . . . . . . . . . . . . . . . . . . . . . 1| |1.2|Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1| |1.3|Applications . . . . . . . . . . . . . . . . . . . . . . . . . . . 1| |1.4|Quick reference data. . . . . . . . . . . . . . . . . . . . . 1| |**2**|**Pinning information. . . . . . . . . . . . . . . . . . . . . . 2**| |**3**|**Ordering information . . . . . . . . . . . . . . . . . . . . . 2**| |**4**|**Marking . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2**| |**5**|**Limiting values. . . . . . . . . . . . . . . . . . . . . . . . . . 3**| |**6**|**Thermal characteristics. . . . . . . . . . . . . . . . . . . 3**| |**7**|**Characteristics. . . . . . . . . . . . . . . . . . . . . . . . . . 3**| |**8**|**Application information. . . . . . . . . . . . . . . . . . . 5**| |8.1|Typical application circuits . . . . . . . . . . . . . . . . 6| |**9**|**Package outline . . . . . . . . . . . . . . . . . . . . . . . . . 8**| |**10**|**Packing information. . . . . . . . . . . . . . . . . . . . . . 9**| |**11**|**Revision history. . . . . . . . . . . . . . . . . . . . . . . . 10**| |**12**|**Legal information. . . . . . . . . . . . . . . . . . . . . . . 11**| |12.1|Data sheet status . . . . . . . . . . . . . . . . . . . . . . 11| |12.2|Defnitions. . . . . . . . . . . . . . . . . . . . . . . . . . . . 11| |12.3|Disclaimers . . . . . . . . . . . . . . . . . . . . . . . . . . . 11| |12.4|Trademarks. . . . . . . . . . . . . . . . . . . . . . . . . . . 11| |**13**|**Contact information. . . . . . . . . . . . . . . . . . . . . 11**| |**14**|**Contents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12**| **==> picture [151 x 121] intentionally omitted <==** Please be aware that important notices concerning this document and the product(s) described herein, have been included in section ‘Legal information’. **© NXP B.V. 2009.** **All rights reserved.** For more information, please visit: http://www.nxp.com For sales office addresses, please send an email to: salesaddresses@nxp.com **Date of release: 27 August 2009 Document identifier: PSSI2021SAY_3**
Updated at June 1, 2026
Nexperia is a dedicated global leader in discretes, logic, and MOSFET devices. Built on over half a century of semiconductor expertise and operating independently since 2017, the company produces consistently reliable components at an exceptional volume of 85 billion units annually. With its own manufacturing facilities, Nexperia delivers industry-leading small packages that combine power and thermal efficiency with best-in-class quality, meeting the rigorous standards of the automotive sector. Our extensive Nexperia portfolio is heavily focused on discrete semiconductors, providing engineers with a robust selection of core building blocks. This includes a comprehensive range of diodes and rectifiers, featuring a vast selection of Zener single diodes and Schottky diodes designed for precise voltage regulation and efficient power routing. Additionally, we offer an expansive array of bipolar transistors and single MOSFETs tailored for reliable switching and amplification in demanding applications. Beyond these primary offerings, the lineup extends into specialized circuit protection and passive components. This includes transient voltage suppressor (TVS) diodes, Zener array diodes, and small signal diodes, alongside dual MOSFETs and fast recovery rectifiers. For comprehensive design needs, the selection also encompasses integrated passive filters, common mode chokes, and precision timers and oscillators, ensuring a complete solution for high-performance electronic systems.
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