NXP Semiconductors PDTC124XS,126

Overview

PDTC124XS,126 from NXP Semiconductors is an NPN resistor-equipped transistor (RET) in TO-92 through-hole package (SOT54), featuring integrated bias resistors R1 = 22 kΩ and R2/R1 = 2.1, V_CEO = 50 V, I_O = 100 mA, and P_tot = 500 mW at T_amb ≤ 25 °C - used for general-purpose switching in industrial control logic interfaces.

For engineers reviewing the PDTC124XS,126 datasheet, PDTC124XS,126 pinout, PDTC124XS,126 application, or PDTC124XS,126 equivalent, key selection criteria include its fixed internal resistor ratio, TO-92 mechanical compatibility, DC current gain (h_FE ≥ 80 at I_C = 5 mA), saturation voltage (V_CEsat ≤ 150 mV), and off-state input threshold (V_I(off) ≤ 0.5 V).

Technical Context

This device integrates two precision bias resistors (R1 = 22 kΩ ± 30 %, R2/R1 = 2.1 ± 21 %) to eliminate external base drive components, enabling direct microcontroller GPIO interfacing without discrete pull-up/pull-down networks. Its NPN topology supports low-side switching with emitter-grounded configuration.

The PDTC124XS,126 operates within −65 °C to +150 °C junction temperature range and delivers h_FE ≥ 80 at V_CE = 5 V and I_C = 5 mA, while maintaining V_CEsat ≤ 150 mV at I_C = 10 mA / I_B = 0.5 mA - confirming suitability for saturated-switching applications requiring predictable turn-on behavior.

Key Specifications

Pinout & Package

PDTC124XS,126 uses the SOT54 (SC-43A/TO-92) through-hole plastic package with 3 leads and standard 2.54 mm lead pitch. Package dimensions: 5.2 × 5.0 × 14.5 mm (L × W × H), with lead length ≥ 3.6 mm and body height ≤ 4.8 mm.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar NPN resistor-equipped transistor applications.

Compared with PDTC124XS,126, PDTC124XK,115 offers identical functionality in SMT form but sacrifices thermal headroom and mechanical compatibility, while MMBT3904,135 increases design complexity and variability despite lower unit cost.

Availability

PDTC124XS,126 is available at Aetrix Electronics and suitable for industrial control logic interfaces, microcontroller output drivers, and relay control circuits requiring stable component supply and long-term obsolescence management.

Supply support for PDTC124XS,126 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

NXP Semiconductors is a global semiconductor company headquartered in Eindhoven, Netherlands, specializing in secure connectivity solutions for automotive, industrial, and IoT applications.

The PDTC124XS,126 belongs to NXP's Resistor-Equipped Transistor (RET) family, designed specifically to simplify discrete switching circuits by integrating precision bias networks - targeting cost-sensitive, high-volume industrial and consumer control systems.

FAQ

What is the pin configuration of PDTC124XS,126?

The PDTC124XS,126 uses SOT54 (TO-92) packaging with three leads: Pin 1 is input (base), Pin 2 is output (collector), and Pin 3 is GND (emitter). This pinout is confirmed in Table 3 of the NXP datasheet and matches standard TO-92 mechanical orientation for low-side switching applications. The PDTC124XS,126 does not share pinout with SOT23 or SOT323 variants in the same series.

Does PDTC124XS,126 support 3.3 V microcontroller logic levels?

Yes, PDTC124XS,126 supports 3.3 V logic drive: its typical on-state input voltage V_I(on) is 1.1 V at I_C = 2 mA, well below 3.3 V, and off-state threshold V_I(off) is ≤ 0.5 V - ensuring clean turn-on and turn-off with standard CMOS outputs. The PDTC124XS,126 achieves full saturation with I_B = 0.5 mA, which corresponds to ~150 µA base current from a 3.3 V source through R1.

What is the maximum ambient temperature for continuous operation of PDTC124XS,126?

The PDTC124XS,126 has an ambient temperature range of −65 °C to +150 °C per Table 6, but its usable continuous operating range depends on power dissipation. At 500 mW P_tot, derating begins above 25 °C ambient; for example, at 75 °C ambient, maximum allowable power drops to ~250 mW. The PDTC124XS,126 junction temperature must remain ≤ 150 °C under all conditions.

Can PDTC124XS,126 replace a standard 2N3904 in existing designs?

PDTC124XS,126 is not a drop-in replacement for 2N3904 due to integrated bias resistors and different pinout: it requires no external base resistors but cannot be used in configurations needing variable base drive or linear amplification. The PDTC124XS,126 is optimized for digital switching, whereas 2N3904 serves broader analog/digital roles. Direct substitution may cause incorrect biasing or open-circuit failure.

What is the thermal resistance of PDTC124XS,126?

The PDTC124XS,126 has a junction-to-ambient thermal resistance R_th(j-a) of 250 K/W in free air when mounted on an FR4 PCB with standard footprint (Table 7). This value assumes single-sided copper, tin-plated traces, and no heatsinking - meaning a 125 °C junction-to-ambient delta corresponds to 500 mW dissipation, aligning with its rated P_tot. The PDTC124XS,126 thermal performance is superior to SMT variants like PDTC124XK due to larger TO-92 mass and lead-frame conduction path.