Send an Inquiry

To receive a quote for your project, please fill in the following information, and we’ll get back to you promptly.

Submit Inventory List

Please fill in the following information, and we’ll get back to you promptly.

Home > Products > Discrete Semiconductor Products > Transistors > Bipolar (BJT) > Single Bipolar Transistors

onsemi 2SA1705S-AN

Name: 2SA1705S-AN
Brand: onsemi
SKU: 2SA1705S-AN
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

Compare

Part No.:: 2SA1705S-AN

Manufacturer:: onsemi

Category:: Single Bipolar Transistors

Package:: SC-71

Datasheet:: 2SA1705S-AN.pdf

Description:: TRANS PNP 50V 1A 3-NMP

Quantity:: RFQ Add To RFQ list

Payment:

Shipping:

Inventory:8,711

Please send an inquiry. Send us your inquiry, and we will respond immediately.

Product details

Overview

2SA1705S-AN from onsemi is a PNP bipolar junction transistor (BJT) rated for -50 V V_CEO, -1 A continuous collector current, and low -180 mV typical V_CE(sat) at -500 mA/-50 mA drive. It uses FBET process technology for fast switching and targets voltage regulators, relay drivers, and lamp drivers in industrial control and power management circuits.

For engineers reviewing the 2SA1705S-AN datasheet, pinout, applications, or equivalent options, key selection criteria include verified V_CE(sat) ≤ -500 mV, h_FE rank S (140–280), SC-71 (NMP) package compatibility, and f_T = 150 MHz performance under -10 V/-50 mA conditions.

Technical Context

This PNP BJT operates with a maximum junction temperature of 150°C and supports pulsed collector current up to -2 A. Its FBET process enables fast switching with t_on = 40 ns, t_stg = 300 ns, and t_f = 30 ns under specified test conditions (V_CC = -25 V, I_C = -500 mA, I_B1 = -50 mA).

Electrical behavior is characterized across temperature: h_FE remains stable from -25°C to +75°C, V_CE(sat) increases only marginally with rising ambient, and Cob = 12 pF at V_CB = -10 V ensures predictable high-frequency response in switching nodes.

Key Specifications

Parameter	Value and Actual Design Meaning
V_CEO	-50 V - Maximum safe collector-emitter blocking voltage in common-emitter configuration
I_C (cont.)	-1 A - Continuous DC collector current rating at T_a = 25°C, derates per PC–Ta curve
V_CE(sat)	-180 to -500 mV - Confirmed saturation voltage at I_C = -500 mA / I_B = -50 mA, critical for low-loss switching
h_FE (Rank S)	140–280 - DC current gain range at V_CE = -2 V / I_C = -100 mA, used for base drive sizing
f_T	150 MHz - Gain-bandwidth product at V_CE = -10 V / I_C = -50 mA, defines usable frequency limit
C_ob	12 pF - Output capacitance at V_CB = -10 V / f = 1 MHz, impacts switching node ringing and drive loss
P_C	0.9 W - Maximum power dissipation at T_a = 25°C, requires thermal design for >100 mA average loads

Pinout & Package

Package: SC-71 (JEITA/JEDEC), also designated NMP (Taping); surface-mount, 3-terminal, plastic molded case with 0.275 g mass and 6.9 mm × 4.5 mm footprint.

Pin/Terminal	Circuit Role	Design Meaning
1	Emitter	Current exit terminal; connected to most positive rail in PNP switch configurations
2	Collector	Current entry terminal; tied to load return path or regulated output node
3	Base	Control input; requires current-limited drive to achieve specified I_C/I_B ratio and V_CE(sat)

Key Features

Feature	Design Value
FBET process technology	Enables consistent low V_CE(sat) and tight h_FE distribution across Rank S (140–280)
Fast switching speed	t_on = 40 ns / t_f = 30 ns supports PWM frequencies up to ~5 MHz in hard-switched topologies
Low-output capacitance	C_ob = 12 pF minimizes Miller effect and gate-drive loading in high-side PNP switches
Thermal robustness	T_j(max) = 150°C allows operation in enclosed industrial enclosures without forced air

Applications

Voltage Regulator Control	Relay Driver Circuit
Use Scenario: Linear post-regulation stage in -12 V or -24 V industrial supplies where low dropout and thermal stability are required. IC Role / Device Role / Timing Role: PNP pass transistor configured in emitter-follower topology to source current to load while maintaining precise output voltage. Use Value: V_CE(sat) ≤ -500 mV ensures <0.5 V dropout at 1 A, reducing heat sink requirements vs. higher-V_sat alternatives.	Use Scenario: Driving 12 V or 24 V electromagnetic relays in PLC I/O modules with microcontroller GPIO-level base control. IC Role / Device Role / Timing Role: High-current PNP switch sinking relay coil current when base is pulled low by MCU. Use Value: Fast t_f = 30 ns limits relay contact bounce duration; h_FE ≥ 140 ensures reliable turn-on with ≤5 mA base drive.
Lamp Driver (Incandescent/LED)	Power Supply Sequencing
Use Scenario: On/off control of 12 V automotive lamps or high-brightness LED strings in dashboard lighting systems. IC Role / Device Role / Timing Role: Low-side or high-side current switch managing peak currents up to 1 A during cold filament inrush or LED surge. Use Value: I_CP = -2 A pulse rating handles 5× inrush without secondary breakdown; Pb-free NMP package meets automotive RoHS.	Use Scenario: Enabling/disabling auxiliary rails (-5 V, -3.3 V) after main supply stabilization in multi-rail embedded power systems. IC Role / Device Role / Timing Role: PNP enable switch placed between enable signal and regulator EN pin, providing inverted logic control. Use Value: V_BR_CEO = -50 V exceeds system rail margins; low C_ob prevents false triggering from adjacent high-dV/dt signals.

Voltage Regulator Control

Relay Driver Circuit

Use Scenario: Linear post-regulation stage in -12 V or -24 V industrial supplies where low dropout and thermal stability are required.

IC Role / Device Role / Timing Role: PNP pass transistor configured in emitter-follower topology to source current to load while maintaining precise output voltage.

Use Value: V_CE(sat) ≤ -500 mV ensures <0.5 V dropout at 1 A, reducing heat sink requirements vs. higher-V_sat alternatives.

Use Scenario: Driving 12 V or 24 V electromagnetic relays in PLC I/O modules with microcontroller GPIO-level base control.

IC Role / Device Role / Timing Role: High-current PNP switch sinking relay coil current when base is pulled low by MCU.

Use Value: Fast t_f = 30 ns limits relay contact bounce duration; h_FE ≥ 140 ensures reliable turn-on with ≤5 mA base drive.

Lamp Driver (Incandescent/LED)

Power Supply Sequencing

Use Scenario: On/off control of 12 V automotive lamps or high-brightness LED strings in dashboard lighting systems.

IC Role / Device Role / Timing Role: Low-side or high-side current switch managing peak currents up to 1 A during cold filament inrush or LED surge.

Use Value: I_CP = -2 A pulse rating handles 5× inrush without secondary breakdown; Pb-free NMP package meets automotive RoHS.

Use Scenario: Enabling/disabling auxiliary rails (-5 V, -3.3 V) after main supply stabilization in multi-rail embedded power systems.

IC Role / Device Role / Timing Role: PNP enable switch placed between enable signal and regulator EN pin, providing inverted logic control.

Use Value: V_BR_CEO = -50 V exceeds system rail margins; low C_ob prevents false triggering from adjacent high-dV/dt signals.

Equivalent & Alternatives

The following parts are listed as comparable options for similar PNP switching transistor applications.

Alternative Part	Technical Difference	Application Difference	Selection Advice
2SA1037AK-TL-E	V_CEO = -50 V, I_C = -150 mA, h_FE = 120–270, SC-70 package (smaller, lower power)	Not suitable for 1 A continuous loads; limited to <200 mA average current	Select only for space-constrained, low-power bias or signal switching where 2SA1705S-AN's current capability is excessive
MMBT2907ALT1G	V_CEO = -60 V, I_C = -600 mA, h_FE = 100–300, SOT-23 package	Lower I_C rating and higher V_CE(sat) (~-700 mV typ) reduce efficiency in 500 mA+ loads	Acceptable for medium-current relay/lamp drivers where thermal headroom exists and footprint compatibility permits

Compared with 2SA1705S-AN, the 2SA1037AK-TL-E offers smaller size but insufficient current handling, while MMBT2907ALT1G provides higher V_CEO margin but sacrifices saturation voltage and thermal capability-neither is pin-compatible, and both require PCB layout revision.

Availability

2SA1705S-AN is available at Aetrix Electronics and suitable for voltage regulators, relay drivers, and lamp drivers requiring stable component supply, RoHS-compliant packaging, and consistent Rank S h_FE binning.

Supply support for 2SA1705S-AN 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

onsemi (formerly ON Semiconductor) is a global semiconductor supplier delivering energy-efficient, intelligent power and sensing solutions for automotive, industrial, cloud, medical, and IoT applications.

The 2SA1705S-AN belongs to onsemi's general-purpose bipolar transistor product line, engineered for cost-sensitive, high-reliability discrete switching in industrial power management and electromechanical interface circuits.

FAQ

What is the h_FE range for 2SA1705S-AN?

The 2SA1705S-AN is binned to Rank S, with DC current gain h_FE specified from 140 to 280 at V_CE = -2 V and I_C = -100 mA. This range is guaranteed per unit and documented in the device marking and shipping documentation. The 2SA1705S-AN does not share the broader 200–400 h_FE range assigned to the 2SA1705T-AN variant.

Is 2SA1705S-AN pin-compatible with 2SA1705T-AN?

Yes, the 2SA1705S-AN and 2SA1705T-AN share identical SC-71 (NMP) package dimensions, pin assignment (Emitter=1, Collector=2, Base=3), and mechanical outline. They differ only in h_FE binning (S vs. T) and associated electrical test limits-not in physical or connection compatibility.

What is the maximum allowable pulsed collector current for 2SA1705S-AN?

The 2SA1705S-AN supports a peak pulsed collector current I_CP of -2 A under conditions defined in the datasheet: single pulse, 1 ms width, duty cycle ≤1%, and T_a = 25°C. Exceeding these conditions risks secondary breakdown or accelerated degradation. The 2SA1705S-AN must be operated within its Safe Operating Area (SOA) curve for reliability.

Does 2SA1705S-AN meet lead-free and RoHS requirements?

Yes, the 2SA1705S-AN is manufactured as a Pb-free device and complies with EU RoHS Directive 2011/65/EU. The "-AN" suffix explicitly denotes lead-free taping and termination. Packaging markings and shipping documentation confirm compliance, and the device carries no exemptions requiring declaration.

What is the thermal resistance junction-to-ambient (R_θJA) for 2SA1705S-AN?

The datasheet does not specify R_θJA as a fixed value due to strong dependence on PCB copper area and airflow. However, the 2SA1705S-AN's 0.9 W P_C rating at T_a = 25°C implies an effective R_θJA ≈ 111°C/W under standard JEDEC test board conditions. Actual R_θJA must be measured or simulated for the target layout; the 2SA1705S-AN's SC-71 package requires ≥100 mm² of 2-oz copper for full power operation.

2SA1705S-AN Specifications

Product attributes: Attribute value

Manufacturer:: onsemi

Series:: -

Package/Case:: SC-71

Packaging:: Tape & Reel (TR)

Product Status:: Obsolete

Transistor Type:: PNP

Current - Collector (Ic) (Max):: 1 A

Voltage - Collector Emitter Breakdown (Max):: 50 V

Vce Saturation (Max) @ Ib, Ic:: 500mV @ 50mA, 500mA

Current - Collector Cutoff (Max):: 100nA (ICBO)

DC Current Gain (hFE) (Min) @ Ic, Vce:: 100 @ 100mA, 2V

Power - Max:: 900 mW

Frequency - Transition:: 150MHz

Operating Temperature:: 150°C (TJ)

Grade:: -

Qualification:: -

Mounting Type:: Through Hole

Supplier Device Package:: 3-NMP

2SA1705S-AN FAQ

1.How can I place an order for 2SA1705S-AN through Aetrix?

Please submit a Request for Quotation (RFQ) for 2SA1705S-AN 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 2SA1705S-AN reliable?

The price and inventory of 2SA1705S-AN are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for 2SA1705S-AN is usually 5 days.

3.What payment methods are accepted for 2SA1705S-AN?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for 2SA1705S-AN transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for 2SA1705S-AN?

2SA1705S-AN orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your 2SA1705S-AN 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 2SA1705S-AN?

For technical support, including 2SA1705S-AN datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your 2SA1705S-AN requirements.

6.How does Aetrix verify that 2SA1705S-AN is sourced from the original manufacturer or authorized distributors?

All 2SA1705S-AN 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 2SA1705S-AN meets industry standards.

7.What is the process for return or replacement of 2SA1705S-AN?

All 2SA1705S-AN units undergo pre-shipment inspection (PSI). If there is an issue with 2SA1705S-AN, 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 2SA1705S-AN part is unused and in its original packaging.

Return procedure for 2SA1705S-AN:

1.Submit a request within 90 days.

2.Obtain a Return Material Authorization (RMA) from Aetrix.

Tech Hub

2026-09-09 Counterfeit Electronic Components: How to Detect, Authenticate, and Test Suspect Parts

Counterfeit components can hide behind convincing markings and passing basic function tests. This engineering reference covers source traceability, external inspection, X-ray, XRF, electrical testing, …

2026-09-08 Obsolete Electronic Components: How to Source and Evaluate Replacements

A practical engineering and sourcing framework covering lifecycle verification, lifetime-buy calculations, replacement qualification, supplier checks and counterfeit-risk controls.

2026-09-07 TTL vs CMOS Logic Levels: 74HC and 74HCT Compatibility Explained

TTL and CMOS logic families differ in thresholds, loading, output drive, power and timing. This engineering guide compares 74HC and 74HCT, calculates noise margins and checks 3.3 V/5 V compatibility.

2026-09-04 Logic Level Shifter: How to Connect 3.3V and 5V Logic Safely

A practical engineering guide to 3.3V and 5V logic compatibility, input thresholds, resistor dividers, translator ICs, MOSFET level shifting, I2C pull-ups, timing limits and power-sequencing risks.

2026-09-03 74HC595 vs TPIC6B595: Output Drive, Pinout, Current, and Load Selection

The 74HC595 uses push-pull logic outputs, while the TPIC6B595 uses 50 V open-drain DMOS sinks for higher-power loads. This guide compares timing, current limits, 3.3 V interfacing, load wiring, thermal…

2026-09-02 74HC595 Pinout, Timing, Output Current, and Applications

The 74HC595 converts serial data into eight stable parallel outputs. This guide covers pin functions, shift and storage timing, OE and MR behavior, drive-current limits, cascading, voltage compatibilit…

2026-09-01 Latch vs Flip-Flop: Timing, Differences and Design Choices

A technical comparison of level-sensitive latches and edge-triggered flip-flops, covering timing windows, setup and hold limits, master–slave operation, time borrowing, race-through, HDL inference and…

2026-08-30 D Latch Circuit: Truth Table, Timing, ICs and Applications

A D latch stores one bit while Enable controls when data can pass. This reference covers gate-level operation, truth tables, transparency, setup and hold timing, LE versus OE, common ICs and practical …

2026-08-28 SR Latch Explained: NOR and NAND Circuits, Truth Tables, and Applications

An SR latch stores one bit through cross-coupled feedback. This engineering reference covers NOR and NAND implementations, truth tables, forbidden-state recovery, gated operation, switch debouncing, fa…

2026-08-27 Latch Circuit: SR and D Latches, Truth Tables, Timing, and Applications

Latch circuits retain one bit through feedback. This technical reference covers SR and D latches, truth tables, transparency, timing limits, latch-versus-flip-flop behavior, applications and common log…