onsemi TIP112

Overview

TIP112 from ON Semiconductor is an NPN epitaxial silicon Darlington transistor in a TO-220 package, rated for 100 V V_CEO, 2 A DC collector current, and 50 W collector dissipation at T_C = 25°C. It features monolithic construction with built-in base-emitter shunt resistors (R₁ ≈ 10 kΩ, R₂ ≈ 0.6 kΩ), h_FE ≥ 1000 at I_C = 1 A, and V_CE(sat) ≤ 2.5 V at I_C = 2 A / I_B = 8 mA - used in industrial linear power control and relay driver circuits.

For engineers reviewing the TIP112 datasheet, pinout, applications, or equivalent options, key selection considerations include its 100 V blocking capability, integrated bias resistors enabling single-resistor base drive, low saturation voltage under 2 A load, thermal derating behavior above 25°C case temperature, and compatibility with TO-220 heatsink mounting in high-current switching designs.

Technical Context

The TIP112 implements a two-stage monolithic Darlington configuration with internal base-emitter shunt resistors to ensure reliable turn-off and reduce external component count. Its high h_FE (≥1000 at 1 A) enables direct microcontroller GPIO driving without additional amplification stages.

It operates as a medium-power, medium-voltage linear/switching amplifier with defined safe operating area (SOA) limits up to 100 V and 2 A DC, and supports pulsed operation up to 4 A with duty cycle ≤2% and pulse width ≤300 μs per electrical characteristics table.

Key Specifications

Pinout & Package

Package: TO-220 3L (Single Gauge), through-hole, vertical mounting with metal tab electrically connected to collector. Requires mechanical isolation when mounted to heatsink unless collector is at system ground potential.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar NPN Darlington transistor applications.

Compared with BD679A and TIP122, the TIP112 provides superior DC current gain stability at 1–2 A loads and full 100 V blocking margin, making it preferred for industrial 48 V systems where both voltage headroom and gain consistency are critical.

Availability

TIP112 is available at Aetrix Electronics and suitable for industrial relay drivers, linear power regulators, and DC motor controllers requiring stable component supply across extended production lifecycles.

Supply support for TIP112 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 power management, analog, sensor, and discrete solutions for automotive, industrial, and cloud power applications.

The TIP112 belongs to ON Semiconductor's legacy high-voltage bipolar transistor product line, designed specifically for ruggedized industrial switching and linear regulation where reliability, voltage margin, and simplified drive requirements are prioritized.

FAQ

What is the maximum continuous collector current for the TIP112?

The TIP112 has a maximum DC collector current rating of 2 A at case temperature T_C = 25°C. This value decreases with rising case temperature per the power derating curve in the datasheet - for example, at T_C = 100°C, the usable I_C drops to approximately 1.2 A. Sustained operation near 2 A requires effective heatsinking to maintain T_C ≤ 50°C. The TIP112 also supports 4 A pulsed current with ≤2% duty cycle and pulse width ≤300 μs.

Does the TIP112 require external base resistors for proper operation?

No, the TIP112 does not require external base resistors for basic on/off switching because it integrates monolithic base-emitter shunt resistors (R₁ ≈ 10 kΩ, R₂ ≈ 0.6 kΩ). These resistors ensure reliable turn-off by bleeding off stored charge and prevent false triggering from leakage or noise. However, an external series base resistor is still needed to limit drive current from the controlling source - typically sized to deliver 8–15 mA at the chosen V_BE (~2.8 V).

What is the collector-emitter saturation voltage of the TIP112 under full load?

The TIP112 specifies V_CE(sat) ≤ 2.5 V at I_C = 2 A and I_B = 8 mA. At lower currents such as I_C = 1 A, V_CE(sat) is typically ≤ 1.8 V. This saturation voltage directly determines conduction loss (P_cond = V_CE(sat) × I_C) and impacts thermal design - e.g., at 2 A, conduction loss is ≤5 W, requiring appropriate heatsinking to maintain junction temperature below 150°C.

Can the TIP112 replace the TIP122 in existing designs?

The TIP112 can often replace the TIP122 in existing designs due to identical TO-220 package, pinout, and 100 V V_CEO rating. However, the TIP112 guarantees h_FE ≥ 1000 at I_C = 1 A, whereas the TIP122 specifies h_FE ≥ 1000 at I_C = 0.5 A. For applications operating near 1–2 A, the TIP112 provides more consistent gain margin. Verify base drive capability and thermal performance in the target circuit before substitution.

What is the safe operating area (SOA) limitation for the TIP112 at 50 V V_CE?

Per the SOA graph in the TIP112 datasheet, at V_CE = 50 V, the maximum allowable DC collector current is approximately 1.4 A. For pulsed operation (≤300 μs, ≤2% duty), the limit rises to ~2.5 A. Exceeding these boundaries risks secondary breakdown or thermal runaway. Designers must ensure that the operating point - defined by simultaneous V_CE and I_C - remains within the SOA envelope across all conditions, including transients and startup surges.