onsemi KSA1175YTA

Overview

KSA1175YTA from ON Semiconductor (formerly Fairchild) is a PNP epitaxial silicon transistor designed for low-frequency amplifier and switching applications, with V_CEO = −50 V, I_C = −150 mA, P_C = 250 mW, h_FE = 350–700 (Y-class), and TO-92S package. It serves as a complement to the NPN KSC2785 in push-pull or differential pair configurations.

For engineers reviewing the KSA1175YTA datasheet, pinout, applications, or equivalent options, key selection criteria include guaranteed h_FE range (350–700), low V_CE(sat) (−0.18 V min at I_C = −100 mA), noise figure (6.0–20 dB), f_T up to 180 MHz, and TO-92S mechanical compatibility in space-constrained analog designs.

Technical Context

This PNP bipolar junction transistor operates in linear amplification and saturated switching modes. Its DC current gain is binned per Y-class (h_FE = 350–700), and it delivers V_CE(sat) ≤ −0.3 V at I_C = −100 mA / I_B = −10 mA, enabling efficient low-voltage switching.

With f_T = 50–180 MHz and C_ob = 2.8 pF at V_CB = −10 V, the KSA1175YTA supports audio-frequency amplification and medium-speed digital signal routing while maintaining low capacitive loading on driving stages.

Key Specifications

Pinout & Package

Package: TO-92S (3-lead plastic through-hole), lead-to-lead width 2.31 mm ±0.20 mm, body height 4.00 mm ±0.20 mm, standard EIAJ outline.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar PNP small-signal transistor applications.

Compared with MPSA92 and BC557B, the KSA1175YTA offers superior h_FE consistency (350–700), lower V_CE(sat), and TO-92S compactness-making it optimal for space-limited, low-distortion audio and precision switching where gain matching matters.

Availability

KSA1175YTA is available at Aetrix Electronics and suitable for audio preamplifiers, relay drivers, differential amplifier stages, and LED current switches requiring stable component supply and tight h_FE binning.

Supply support for KSA1175YTA 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 (acquired Fairchild Semiconductor in 2016) is a global supplier of energy-efficient semiconductor components for automotive, industrial, cloud computing, and IoT applications.

The KSA1175YTA belongs to Fairchild's legacy small-signal transistor family, engineered specifically for low-noise, low-distortion analog amplification and reliable low-voltage switching in cost-sensitive consumer and industrial electronics.

FAQ

What is the h_FE range guaranteed for KSA1175YTA?

The KSA1175YTA is Y-class binned with a guaranteed DC current gain (h_FE) range of 350 to 700 when measured at V_CE = −6 V and I_C = −1 mA. This tight binning enables predictable biasing in amplifier and switching circuits without post-manufacturing sorting. The KSA1175YTA datasheet confirms this classification under "hFE Classification" table.

Is KSA1175YTA pin-compatible with KSC2785?

No-KSA1175YTA (PNP) and KSC2785 (NPN) are complementary devices but not pin-compatible; they share functional symmetry (e.g., same V_CEO, I_C, package), but KSA1175YTA uses E-B-C pinout (1–2–3), whereas KSC2785 uses E-C-B. Direct substitution requires PCB layout revision. The KSA1175YTA datasheet explicitly states "Complement to KSC2785", not pin-for-pin replacement.

What is the maximum operating junction temperature for KSA1175YTA?

The KSA1175YTA has a maximum rated junction temperature (T_J) of 150°C, as specified in its Absolute Maximum Ratings table. Derating is required above 25°C ambient; power dissipation must be reduced linearly beyond that point per the thermal resistance curve. This T_J limit ensures long-term reliability in enclosed audio enclosures or industrial control housings where the KSA1175YTA operates.

Does KSA1175YTA support audio-frequency amplification?

Yes-the KSA1175YTA supports audio-frequency amplification with f_T up to 180 MHz and noise figure as low as 6.0 dB at 100 Hz, making it suitable for microphone preamps and tone control stages. Its h_FE stability over I_C (per Figure 2) and low V_CE(sat) preserve signal integrity across the 20 Hz–20 kHz band. These characteristics are confirmed in the KSA1175YTA Typical Characteristics section.

What package type does KSA1175YTA use?

KSA1175YTA uses the TO-92S package-a compact, 3-lead through-hole plastic case with standardized EIAJ outline, measuring 4.00 mm × 2.31 mm × 3.72 mm. Pin 1 is Emitter, Pin 2 is Collector, Pin 3 is Base. This package is distinct from standard TO-92 due to tighter dimensional tolerances and optimized lead spacing for automated insertion. The KSA1175YTA package drawing is provided in the datasheet Rev. A2.