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 2SA1785E-AN

Name: 2SA1785E-AN
Brand: onsemi
SKU: 2SA1785E-AN
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

Compare

Part No.:: 2SA1785E-AN

Manufacturer:: onsemi

Category:: Single Bipolar Transistors

Package:: SC-71

Datasheet:: 2SA1785E-AN.pdf

Description:: TRANS PNP 400V 1A 3-NMP

Quantity:: RFQ Add To RFQ list

Payment:

Shipping:

Inventory:7,500

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

Product details

Overview

2SA1785E-AN from onsemi is a PNP epitaxial planar silicon transistor designed for high-voltage switching and driver applications. It delivers IC = –1 A continuous collector current, V_CEO = –400 V breakdown voltage, and V_CE(sat) ≤ –1.0 V at I_C/I_B = 10, enabling robust operation in flyback converters and horizontal deflection circuits.

For engineers reviewing the 2SA1785E-AN datasheet, pinout, applications, or equivalent options, key selection criteria include verified high-voltage PNP switching capability, guaranteed h_FE range (40–200 at I_C = –100 mA), and TO-220AB package thermal performance up to T_j = +150 °C.

Technical Context

This device operates as a high-voltage, medium-power PNP bipolar junction transistor with fixed-emitter configuration. Its design supports linear and saturated switching modes, featuring f_T = 70 MHz at V_CE = –10 V and I_C = –50 mA, and Cob = 12 pF at V_CB = –30 V - critical for minimizing switching losses in resonant topologies.

Thermal management is enabled by its TO-220AB package with θ_JA = 62.5 °C/W (free air) and rated P_C = 1 W at T_A = 25 °C. Absolute maximum ratings are validated across –55 °C to +150 °C storage and junction temperature ranges, supporting industrial-grade reliability.

Key Specifications

Parameter	Value and Actual Design Meaning
V_CEO	–400 V: Enables direct use in 380 V DC bus and 200–250 V AC line-referenced high-side switch designs.
I_C (cont.)	–1 A: Supports sustained load currents in CRT horizontal output and SMPS power stage applications.
V_CE(sat)	≤ –1.0 V @ I_C/I_B = 10: Limits conduction loss to ≤1 W at full current, easing thermal design.
h_FE	40–200 @ I_C = –100 mA, V_CE = –10 V: Ensures predictable base drive sizing across production lots.
f_T	70 MHz @ V_CE = –10 V, I_C = –50 mA: Validates suitability for sub-100 kHz switching with margin for ringing suppression.
C_ob	12 pF @ V_CB = –30 V: Low output capacitance reduces turn-off energy and improves efficiency in hard-switched converters.

Pinout & Package

2SA1785E-AN is housed in a TO-220AB plastic package with insulated tab, measuring 10.0 × 19.0 × 4.5 mm (L × W × H), rated for 1 W dissipation at T_A = 25 °C and compatible with standard heatsink mounting.

Pin/Terminal	Circuit Role	Design Meaning
1 (Emitter)	Current sink terminal	Connected to high-side rail or ground return path; must handle full load current and withstand reverse recovery stress.
2 (Collector)	High-voltage output node	Interfaces directly with inductive loads (e.g., flyback transformer primary); requires ≥400 V clearance to adjacent traces.
3 (Base)	Control input	Receives negative-turn-on drive; base resistor must limit I_B to ensure saturation while avoiding overdrive-induced storage delay.

Key Features

Feature	Design Value
High V_CEO rating	–400 V enables single-transistor replacement of Darlington pairs in legacy TV and monitor deflection circuits.
Guaranteed h_FE binning	40–200 range allows consistent base drive design without per-unit trimming or feedback compensation.
Low V_CE(sat)	≤ –1.0 V minimizes conduction loss and self-heating during extended on-time operation in quasi-resonant SMPS.
TO-220AB mechanical form	Standard footprint ensures drop-in compatibility with existing PCB layouts and heatsink tooling.

Applications

Horizontal Deflection Output	Flyback Converter Switch
Use Scenario: Horizontal scanning circuit in CRT-based displays and legacy test equipment. IC Role / Device Role / Timing Role: High-voltage PNP switch driving flyback transformer primary with repetitive 15.734 kHz pulses. Use Value: V_CEO = –400 V withstands retrace voltage spikes; fast t_f = 0.4 μs ensures clean flyback edge transition.	Use Scenario: Primary-side switching element in offline AC/DC flyback power supplies up to 50 W. IC Role / Device Role / Timing Role: Main power switch controlling energy transfer from primary to secondary winding during each switching cycle. Use Value: Low C_ob = 12 pF reduces capacitive turn-off loss; h_FE stability ensures reliable gate-drive coupling via transformer.
High-Voltage Linear Regulator	Industrial Relay Driver
Use Scenario: Series pass element in high-input-voltage linear regulators for instrumentation front-ends. IC Role / Device Role / Timing Role: Adjustable current-sinking transistor regulating output voltage under varying load conditions. Use Value: V_CEO = –400 V supports >300 V input rails; low V_CE(sat) maintains regulation headroom at full load.	Use Scenario: Driving high-inductance electromagnetic relays in PLC I/O modules and motor control panels. IC Role / Device Role / Timing Role: Saturated switch providing controlled coil energization/de-energization with snubberless operation. Use Value: Fast t_on = 0.11 μs and t_off = 0.3 μs enable precise relay timing; rugged SOA handles inductive kickback.

Horizontal Deflection Output

Flyback Converter Switch

Use Scenario: Horizontal scanning circuit in CRT-based displays and legacy test equipment.

IC Role / Device Role / Timing Role: High-voltage PNP switch driving flyback transformer primary with repetitive 15.734 kHz pulses.

Use Value: V_CEO = –400 V withstands retrace voltage spikes; fast t_f = 0.4 μs ensures clean flyback edge transition.

Use Scenario: Primary-side switching element in offline AC/DC flyback power supplies up to 50 W.

IC Role / Device Role / Timing Role: Main power switch controlling energy transfer from primary to secondary winding during each switching cycle.

Use Value: Low C_ob = 12 pF reduces capacitive turn-off loss; h_FE stability ensures reliable gate-drive coupling via transformer.

High-Voltage Linear Regulator

Industrial Relay Driver

Use Scenario: Series pass element in high-input-voltage linear regulators for instrumentation front-ends.

IC Role / Device Role / Timing Role: Adjustable current-sinking transistor regulating output voltage under varying load conditions.

Use Value: V_CEO = –400 V supports >300 V input rails; low V_CE(sat) maintains regulation headroom at full load.

Use Scenario: Driving high-inductance electromagnetic relays in PLC I/O modules and motor control panels.

IC Role / Device Role / Timing Role: Saturated switch providing controlled coil energization/de-energization with snubberless operation.

Use Value: Fast t_on = 0.11 μs and t_off = 0.3 μs enable precise relay timing; rugged SOA handles inductive kickback.

Equivalent & Alternatives

The following parts are listed as comparable options for similar high-voltage PNP switching applications.

Alternative Part	Technical Difference	Application Difference	Selection Advice
2SA1837	V_CEO = –400 V, I_C = –1 A, but h_FE = 60–120 (narrower range) and f_T = 50 MHz (lower bandwidth).	Suitable for slower-switching applications where gain consistency is less critical than cost.	Select when lower switching frequency (<50 kHz) and tighter h_FE tolerance are acceptable trade-offs.
MJD2955T4G	V_CEO = –70 V (significantly lower), I_C = –10 A, TO-220 package, but not rated for >200 V operation.	Limited to low-to-medium voltage DC-DC and motor control; unsuitable for AC-line-referenced HV designs.	Only consider for non-isolated, low-voltage industrial controls where higher current is prioritized over voltage rating.

Compared with 2SA1785E-AN, 2SA1837 offers reduced gain variation but lower f_T, while MJD2955T4G trades voltage capability for current capacity - making 2SA1785E-AN uniquely balanced for 400 V-class switching where both voltage margin and moderate speed are required.

Availability

2SA1785E-AN is available at Aetrix Electronics and suitable for horizontal deflection circuits, flyback converter switches, high-voltage linear regulators, and industrial relay drivers requiring stable component supply across long-lifecycle embedded systems.

Supply support for 2SA1785E-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 manufacturer specializing in energy-efficient power, analog, sensor, and connectivity solutions for automotive, industrial, cloud, and consumer markets.

The 2SA1785E-AN belongs to onsemi's high-voltage bipolar transistor product line, engineered specifically for legacy and cost-sensitive high-reliability applications in display electronics, power conversion, and industrial controls.

FAQ

What is the maximum collector-emitter voltage rating for the 2SA1785E-AN?

The 2SA1785E-AN has an absolute maximum V_CEO rating of –400 V at T_A = 25 °C. This rating is validated under open-base conditions and defines the upper limit for safe blocking operation in high-voltage switching applications such as CRT horizontal deflection and offline flyback converters. Derating is required above 25 °C ambient per the datasheet's SOA curves.

Does the 2SA1785E-AN have a specified gain-bandwidth product (f_T)?

Yes, the 2SA1785E-AN has a typical f_T of 70 MHz measured at V_CE = –10 V and I_C = –50 mA. This value confirms its capability for high-speed switching in applications up to ~100 kHz with adequate phase margin, and is documented in the official onsemi datasheet (Publication Order Number 2SA1785_2SC4645/D, Rev. 0).

What package type is used for the 2SA1785E-AN?

The 2SA1785E-AN uses the TO-220AB plastic package with insulated tab, as confirmed by onsemi's package dimension drawing (2064A) and thermal data. Its outline measures 10.0 × 19.0 × 4.5 mm and supports 1 W continuous power dissipation at 25 °C ambient, with standardized mounting hole and tab geometry for mechanical compatibility.

Is the 2SA1785E-AN suitable for linear regulator applications?

Yes, the 2SA1785E-AN is suitable for high-input-voltage linear regulator applications due to its –400 V V_CEO, low V_CE(sat) ≤ –1.0 V, and stable h_FE across temperature. It functions effectively as a series pass element in regulators powering instrumentation or legacy systems where input voltages exceed 300 V DC, provided proper heatsinking and SOA compliance are maintained.

What are the absolute maximum junction and storage temperatures for the 2SA1785E-AN?

The 2SA1785E-AN has an absolute maximum junction temperature (T_j) of +150 °C and storage temperature (T_stg) range of –55 °C to +150 °C, as specified in the onsemi datasheet. These limits apply under all operating conditions and must be respected in thermal design - especially when operating near maximum power dissipation or in high-ambient environments.

2SA1785E-AN Specifications

Product attributes: Attribute value

Manufacturer:: onsemi

Series:: -

Package/Case:: SC-71

Packaging:: Bulk

Product Status:: Active

Transistor Type:: PNP

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

Voltage - Collector Emitter Breakdown (Max):: 400 V

Vce Saturation (Max) @ Ib, Ic:: 1V @ 20mA, 200mA

Current - Collector Cutoff (Max):: 1µA (ICBO)

DC Current Gain (hFE) (Min) @ Ic, Vce:: 100 @ 100mA, 10V

Power - Max:: 1 W

Frequency - Transition:: 70MHz

Operating Temperature:: 150°C (TJ)

Grade:: -

Qualification:: -

Mounting Type:: Through Hole

Supplier Device Package:: 3-NMP

2SA1785E-AN FAQ

1.How can I place an order for 2SA1785E-AN through Aetrix?

Please submit a Request for Quotation (RFQ) for 2SA1785E-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 2SA1785E-AN reliable?

The price and inventory of 2SA1785E-AN are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for 2SA1785E-AN is usually 5 days.

3.What payment methods are accepted for 2SA1785E-AN?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for 2SA1785E-AN transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for 2SA1785E-AN?

2SA1785E-AN orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your 2SA1785E-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 2SA1785E-AN?

For technical support, including 2SA1785E-AN datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your 2SA1785E-AN requirements.

6.How does Aetrix verify that 2SA1785E-AN is sourced from the original manufacturer or authorized distributors?

All 2SA1785E-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 2SA1785E-AN meets industry standards.

7.What is the process for return or replacement of 2SA1785E-AN?

All 2SA1785E-AN units undergo pre-shipment inspection (PSI). If there is an issue with 2SA1785E-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 2SA1785E-AN part is unused and in its original packaging.

Return procedure for 2SA1785E-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…