onsemi MMBTA64LT3G

Overview

MMBTA64LT3G from onsemi is a PNP silicon Darlington transistor in SOT-23 package, rated for −30 V_CEO, −500 mA continuous collector current, and 300 mW dissipation on alumina substrate. It delivers DC current gain of 10,000–20,000 at −100 mA, with V_CE(sat) ≤ −1.5 V and V_BE(on) ≤ −2.0 V, enabling high-gain low-base-drive switching in space-constrained industrial control interfaces.

For engineers reviewing the MMBTA64LT3G datasheet, pinout, applications, or equivalent options, key selection criteria include verified Darlington gain range, SOT-23 thermal derating behavior, −30 V breakdown margin, and AEC-Q101 qualification status for automotive-grade reliability validation.

Technical Context

This device implements a monolithic PNP Darlington pair with integrated base-emitter resistor network absent-requiring external base drive control. Its f_T = 125 MHz supports moderate-speed switching up to ~100 kHz with stable gain across −55°C to +150°C junction temperature range.

Thermal performance is defined for two mounting conditions: 556°C/W R_JA on FR-5 board and 417°C/W on 0.4×0.3×0.024 in. 99.5% alumina substrate. Safe operating area (SOA) curves confirm single-pulse capability up to 1 A for 1 ms at V_CE = −10 V.

Key Specifications

Pinout & Package

MMBTA64LT3G uses the SOT-23 (TO-236) package per Case 318 Style 6, with 2.90 × 1.30 × 1.00 mm footprint and 1.90 mm lead pitch. Pin 1 = Base, Pin 2 = Emitter, Pin 3 = Collector.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MMBTA64LT1G, MMBTA64LT3G offers identical performance in a higher-density reel format, while ZTX951 trades gain and size for voltage headroom-making MMBTA64LT3G optimal for modern SMT-based, high-reliability, medium-voltage switching where space and AEC-Q101 compliance are critical.

Availability

MMBTA64LT3G is available at Aetrix Electronics and suitable for industrial relay drivers, automotive LED tail lights, and low-power HVAC sensors requiring stable component supply, RoHS-compliant sourcing, and AEC-Q101 traceability.

Supply support for MMBTA64LT3G 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 specializing in energy-efficient power management, analog, sensing, and connectivity solutions for automotive, industrial, and cloud infrastructure markets.

MMBTA64LT3G belongs to onsemi's general-purpose bipolar transistor portfolio, engineered for high-reliability discrete switching in cost-sensitive, space-constrained applications demanding AEC-Q101 qualification and Pb-free compliance.

FAQ

What is the maximum safe operating voltage for MMBTA64LT3G in a 24 V industrial control system?

The MMBTA64LT3G has a guaranteed V_CEO rating of −30 V, making it suitable for 24 V nominal systems with transient margins. Under worst-case load-dump conditions (ISO 7637-2 Pulse 5a), peak voltages may reach −35 V; operation within this envelope requires external clamping or derating. The MMBTA64LT3G remains within safe limits if V_CE does not exceed −30 V continuously or −35 V transiently for <100 ms.

Does MMBTA64LT3G require a base resistor, and what value is recommended for driving a 300 mA relay coil?

Yes, MMBTA64LT3G requires an external base resistor to limit drive current and ensure saturation. For a 300 mA load with h_FE ≥ 10,000, a base current of ≥30 μA suffices. With a 3.3 V MCU GPIO and V_BE(on) ≈ −2.0 V, a 43 kΩ resistor yields ~30 μA-verified in Figure 3 of the datasheet. The MMBTA64LT3G achieves full saturation under this condition with V_CE(sat) ≤ −1.5 V.

How does the thermal performance of MMBTA64LT3G differ between FR-5 PCB and alumina substrate mounting?

On FR-5 board, MMBTA64LT3G has R_JA = 556°C/W and PD = 225 mW at 25°C, derating by 1.8 mW/°C. On 0.4×0.3 in. alumina, R_JA improves to 417°C/W with PD = 300 mW and 2.4 mW/°C derating. This means the MMBTA64LT3G can dissipate ~33% more power on ceramic before reaching T_J(max) = +150°C-critical for sealed enclosures or high-ambient environments.

Is MMBTA64LT3G pin-compatible with MMBTA63LT3G, and what design impact does substituting them have?

Yes, MMBTA64LT3G and MMBTA63LT3G share identical SOT-23 pinout (Style 6: Pin 1=Base, Pin 2=Emitter, Pin 3=Collector) and package dimensions. However, MMBTA63LT3G has lower h_FE (5,000–10,000) and is optimized for lower-current loads. Substituting MMBTA64LT3G into an MMBTA63LT3G design improves gain margin but may increase base drive sensitivity; verify stability under worst-case V_BE and temperature extremes for the MMBTA64LT3G.

What packaging format does MMBTA64LT3G ship in, and how does it differ from MMBTA64LT1G?

MMBTA64LT3G ships in tape-and-reel format with 8,000 units per reel, whereas MMBTA64LT1G ships with 3,000 units per reel. Both use Pb-free SOT-23 packaging and identical marking ('V' code for MMBTA64). The MMBTA64LT3G reel size reduces SMT line changeovers in high-volume manufacturing, while electrical and thermal specifications remain fully identical-no redesign or validation is needed when switching between MMBTA64LT1G and MMBTA64LT3G.