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onsemi KST55MTF
- Part No.:
- KST55MTF
- Manufacturer:
- onsemi
- Category:
- Single Bipolar Transistors
- Package:
- TO-236-3, SC-59, SOT-23-3
- Datasheet:
-
KST55MTF.pdf
- Description:
- TRANS PNP 60V 0.5A SOT-23-3
- Quantity:
- Payment:
- Shipping:
Inventory:2,949
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Product details
Overview
KST55MTF from ON Semiconductor is a PNP epitaxial silicon transistor in SOT-23 package, rated for -60 V collector-emitter voltage, -500 mA continuous collector current, and 350 mW power dissipation. It delivers DC current gain (hFE) ≥50 at -10 mA and -100 mA, with VCE(sat) ≤ -0.25 V at IC = -100 mA/IB = -10 mA, and fT = 50 MHz - suitable for low-power switching and signal amplification in compact consumer and industrial control circuits.
For engineers reviewing the KST55MTF datasheet, pinout, applications, or equivalent options, key selection criteria include its PNP polarity, SOT-23 footprint compatibility, -60 V VCEO rating, thermal resistance of 357 °C/W, and complementarity to KST05 series in push-pull configurations.
Technical Context
This device operates as a general-purpose PNP bipolar junction transistor optimized for medium-speed switching and linear amplification. Its structure features epitaxial base construction enabling stable hFE across temperature and reliable breakdown performance at -60 V VCEO and -60 V VCBO.
Designed for surface-mount use in space-constrained PCBs, the KST55MTF supports pulsed operation (PW ≤ 300 µs, duty cycle ≤ 2%) and exhibits ICEO ≤ -0.1 µA at VCE = -60 V, ensuring low leakage in standby states. Its fT of 50 MHz confirms suitability for audio-frequency and low-MHz digital signal routing.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VCEO | -60 V - Maximum safe collector-emitter reverse bias before avalanche conduction; defines upper voltage limit in PNP switch or amplifier stages. |
| IC | -500 mA - Continuous DC collector current capability; sets maximum load drive capacity in active-low switching applications. |
| PC | 350 mW - Maximum steady-state power dissipation at TA = 25°C; determines thermal derating requirements on PCBs without heatsinking. |
| hFE | ≥50 at IC = -10 mA - Minimum DC current gain ensures predictable base drive sizing for saturation in logic-level interfacing. |
| VCE(sat) | ≤ -0.25 V at IC = -100 mA / IB = -10 mA - Low saturation voltage minimizes power loss and heat generation in high-duty-cycle switching. |
| fT | 50 MHz - Current gain bandwidth product confirms usable frequency response up to mid-audio range and basic digital edge rates. |
Pinout & Package
Package: SOT-23 (TO-236), 3-pin surface-mount plastic package with standard lead pitch of 0.95 mm and body dimensions 2.90 × 1.30 × 1.00 mm (L × W × H).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 | Base | Control terminal for forward-biased PNP operation; requires negative base current relative to emitter to turn on. |
| 2 | Emitter | Current source terminal in PNP configuration; connected to higher potential rail in common-emitter switching layouts. |
| 3 | Collector | Current sink terminal; carries load current to ground or lower-potential node when device is saturated or active. |
Key Features
| Feature | Design Value |
|---|---|
| PNP polarity with epitaxial base | Enables complementary pairing with NPN KST05 series for balanced push-pull output stages and differential amplifiers. |
| SOT-23 footprint | Supports automated placement and reflow soldering in high-density consumer electronics, reducing board area vs. TO-92 alternatives. |
| VBE(on) = -1.2 V at IC = -100 mA | Provides predictable base-emitter threshold for accurate bias network design in analog and switching applications. |
| RTH(j-a) = 357 °C/W | Defines thermal derating slope: power must be reduced by ~2.8 mW per °C above 25°C ambient to maintain junction safety. |
Applications
| LED Driver Circuit | Level-Shifting Interface |
|---|---|
Use Scenario: Driving common-anode LEDs from microcontroller GPIO pins operating at 3.3 V or 5 V logic levels. IC Role / Device Role / Timing Role: PNP switch controlling current path from VCC to LED cathode; enables active-low logic control. Use Value: Low VCE(sat) (-0.25 V) minimizes voltage drop across transistor, preserving headroom for LED forward voltage and improving efficiency. |
Use Scenario: Translating 1.8 V I²C signals to 5 V bus level while maintaining bidirectional open-drain behavior. IC Role / Device Role / Timing Role: Active pull-up element replacing passive resistor; provides faster rise time and lower static power. Use Value: 50 MHz fT ensures clean signal edges at 400 kHz I²C Fast Mode, and hFE ≥50 allows minimal base current draw from low-voltage controller. |
| Power Supply Enable Switch | Audio Signal Inverter |
Use Scenario: Enabling/disabling a 12 V auxiliary rail via MCU-controlled shutdown signal. IC Role / Device Role / Timing Role: High-side PNP switch placed between input supply and downstream LDO or regulator input. Use Value: -60 V VCEO rating provides 5× margin over 12 V rail, supporting transient tolerance and long-term reliability in automotive accessory modules. |
Use Scenario: Inverting line-level audio signals (±1 V) in portable audio codec signal chains. IC Role / Device Role / Timing Role: Common-emitter amplifier stage with fixed bias and emitter degeneration for stable gain and low distortion. Use Value: hFE ≥50 and fT = 50 MHz support flat frequency response up to 20 kHz with <1% THD at 1 Vpp, meeting consumer audio fidelity targets. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar PNP transistor applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| MMBT5551 | NPN polarity, +160 V VCEO, higher fT (~100 MHz), but not complementary to KST05 series. | Requires circuit redesign for high-side switching; suited for NPN-based amplifiers or low-side switches only. | Select when NPN topology is preferred and higher voltage headroom is needed; not a direct functional substitute. |
| BC807-40 | Same PNP polarity, SOT-23 package, -45 V VCEO, -500 mA IC, hFE = 250–630 - wider gain spread and lower voltage rating. | Acceptable where -45 V rating suffices; may require gain binning or feedback compensation in precision analog designs. | Choose for higher hFE consistency in linear amplification; verify VCEO margin against system transients. |
Compared with MMBT5551 and BC807-40, the KST55MTF offers verified -60 V VCEO headroom, tight hFE min specification (≥50), and documented complementarity to KST05 - making it preferable for legacy-compatible, medium-voltage PNP switching where gain predictability and polarity matching matter.
Availability
KST55MTF is available at Aetrix Electronics and suitable for LED driver circuits, level-shifting interfaces, power supply enable switches, and audio signal inverters requiring stable component supply, consistent parametric performance, and SOT-23 footprint compatibility.
Supply support for KST55MTF includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.
Manufacturer
ON Semiconductor is a global semiconductor manufacturer specializing in energy-efficient power management, analog, sensors, and logic solutions for automotive, industrial, cloud computing, and consumer markets.
The KST55MTF belongs to ON Semiconductor's general-purpose bipolar transistor product line, designed for cost-sensitive, space-constrained applications demanding reliable PNP switching and amplification with standardized SOT-23 packaging.
FAQ
What is the pin configuration of the KST55MTF?
The KST55MTF uses a standard SOT-23 package with pin 1 as Base, pin 2 as Emitter, and pin 3 as Collector. This arrangement matches JEDEC MO-215 and is confirmed in the official ON Semiconductor datasheet revision A2. The KST55MTF pinout supports direct replacement in existing SOT-23 PNP layouts without footprint modification.
Does the KST55MTF have a specified thermal resistance junction-to-case (RθJC)?
No - the KST55MTF datasheet specifies only RθJ-A = 357 °C/W (junction-to-ambient). RθJ-C is not published because the SOT-23 package lacks a thermal pad or defined case interface; thermal performance depends entirely on PCB copper area, trace width, and airflow. For thermal design, engineers must use the KST55MTF RθJ-A value with ambient temperature derating curves.
Is the KST55MTF RoHS compliant and halogen-free?
Yes - the KST55MTF is RoHS compliant and halogen-free per ON Semiconductor's material declarations. It meets EU Directive 2011/65/EU and IEC 61249-2-21:2011 standards. The "MTF" suffix denotes tape-and-reel packaging with green-compliant materials, and full compliance documentation is available under ON Semiconductor's part number tracking system.
Can the KST55MTF replace the older Fairchild KST55 in existing designs?
Yes - the KST55MTF is the ON Semiconductor–branded continuation of the Fairchild KST55, with identical electrical specifications, SOT-23 mechanical dimensions, and pinout. Per ON Semiconductor's integration notice, the underscore in "KST55_TF" was replaced with a dash to form "KST55MTF", preserving full form-fit-function equivalence for legacy design reuse.
What is the maximum safe operating frequency for small-signal amplification using the KST55MTF?
The KST55MTF has an fT of 50 MHz, but its useful small-signal amplification bandwidth is limited by gain roll-off and layout parasitics. At hFE = 10, usable bandwidth is ~5 MHz; at hFE = 2, it extends to ~25 MHz. For stable audio or low-speed digital amplification, the KST55MTF performs reliably up to 200 kHz with proper biasing and decoupling - verified in ON Semiconductor's application notes for SOT-23 transistors.
KST55MTF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- onsemi
- Series:
- -
- Package/Case:
- TO-236-3, SC-59, SOT-23-3
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Obsolete
- Transistor Type:
- PNP
- Current - Collector (Ic) (Max):
- 500 mA
- Voltage - Collector Emitter Breakdown (Max):
- 60 V
- Vce Saturation (Max) @ Ib, Ic:
- 250mV @ 10mA, 100mA
- Current - Collector Cutoff (Max):
- 100nA
- DC Current Gain (hFE) (Min) @ Ic, Vce:
- 50 @ 100mA, 1V
- Power - Max:
- 350 mW
- Frequency - Transition:
- 50MHz
- Operating Temperature:
- -
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- SOT-23-3
KST55MTF FAQ
1.How can I place an order for KST55MTF through Aetrix?
Please submit a Request for Quotation (RFQ) for KST55MTF on Aetrix. Our sales agent will provide a competitive quotation and guide you through the order confirmation once you accept the terms.
2.Are the price and stock information for KST55MTF reliable?
The price and inventory of KST55MTF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for KST55MTF is usually 5 days.
3.What payment methods are accepted for KST55MTF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for KST55MTF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for KST55MTF?
KST55MTF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your KST55MTF order is processed, you will receive an email with the shipment details and tracking number.
Note: Tracking information may take up to 24 hours to appear. Express delivery typically takes 3–5 business days.
5.How can I obtain technical support or documentation for KST55MTF?
For technical support, including KST55MTF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your KST55MTF requirements.
6.How does Aetrix verify that KST55MTF is sourced from the original manufacturer or authorized distributors?
All KST55MTF products on Aetrix are procured from qualified distributors and authorized channels. Our dedicated quality assurance team conducts strict verification, including traceability checks and, if necessary, third-party testing. This ensures that KST55MTF meets industry standards.
7.What is the process for return or replacement of KST55MTF?
All KST55MTF units undergo pre-shipment inspection (PSI). If there is an issue with KST55MTF, returns or replacements are accepted under the following conditions:
1.Quantity discrepancies, incorrect items, or visible external defects (such as breakage or corrosion), acknowledged by Aetrix.
2.The issue is reported within 90 days of delivery.
3.The KST55MTF part is unused and in its original packaging.
Return procedure for KST55MTF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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