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Home > Products > Discrete Semiconductor Products > Transistors > Bipolar (BJT) > Single Bipolar Transistors

onsemi MMBTA70LT1

Name: MMBTA70LT1
Brand: onsemi
SKU: MMBTA70LT1
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: MMBTA70LT1

Manufacturer:: onsemi

Category:: Single Bipolar Transistors

Package:: TO-236-3, SC-59, SOT-23-3

Datasheet:: MMBTA70LT1.pdf

Description:: TRANS PNP 40V 0.1A SOT23-3

Quantity:: RFQ Add To RFQ list

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Product details

Overview

MMBTA70LT1 from onsemi is a general-purpose PNP silicon bipolar junction transistor in SOT-23 package, rated for −40 V V_CEO, −100 mA I_C, and 225 mW power dissipation on FR-5 board; it delivers h_FE = 40–400 at −5 mA/−10 V, V_CE(sat) ≤ −0.25 V at −10 mA/−1 mA drive, and f_T = 125 MHz - used in low-power signal switching and amplification stages of portable audio bias networks and LED driver current sinks.

For engineers reviewing the MMBTA70LT1 datasheet, pinout, applications, or equivalent options, key selection criteria include verified PNP polarity, SOT-23 pin configuration (Base–Emitter–Collector), guaranteed −40 V breakdown, noise performance below 5 nV/√Hz at 1 kHz, and thermal resistance of 556 °C/W on standard PCBs.

Technical Context

This PNP BJT operates in active and saturation regions with defined DC gain linearity across −0.1 to −100 mA collector current and stable V_CE(sat) under I_C/I_B = 10. Its f_T = 125 MHz enables use in RF predriver and oscillator buffer stages up to ~30 MHz fundamental frequency.

Thermal design relies on two validated dissipation modes: 225 mW at 25°C on FR-5 (derating 1.8 mW/°C) and 300 mW on alumina (derating 2.4 mW/°C), with corresponding R_JA values of 556 °C/W and 417 °C/W - critical for thermally constrained space-constrained designs.

Key Specifications

Parameter	Value and Actual Design Meaning
V_CEO	−40 V - Maximum safe collector-emitter voltage before avalanche breakdown; defines rail compatibility in negative-supply logic interfaces.
I_C (cont.)	−100 mA - Continuous collector current limit; sets maximum load drive capability in discrete switch or current-source configurations.
h_FE	40–400 - DC current gain range at −5 mA/−10 V; determines base drive requirements and stability margin in linear amplifier feedback loops.
V_CE(sat)	≤ −0.25 V at −10 mA/−1 mA - Low saturation voltage ensures minimal power loss and heat generation in switching applications.
f_T	125 MHz - Transition frequency confirms usable bandwidth for high-speed digital buffering and narrowband RF amplification.
C_obo	≤ 4.0 pF at −10 V - Output capacitance impacts high-frequency gain roll-off and switching speed in tuned circuits.
R_JA (FR-5)	556 °C/W - Junction-to-ambient thermal resistance on standard epoxy PCB; used to calculate temperature rise under real operating power.

Pinout & Package

SOT-23 (TO-236) surface-mount package, 2.90 × 1.30 × 1.00 mm body size, 1.90 mm lead pitch, JEDEC case 318, Style 6 marking. RoHS-compliant, Pb-free, halogen-free/BFR-free construction.

Pin/Terminal	Circuit Role	Design Meaning
1	Base	Control terminal for forward-biased PNP operation; requires negative base current relative to emitter to turn on.
2	Emitter	Current source terminal in PNP topology; connected to higher potential (e.g., V_CC) in common-emitter switch configurations.
3	Collector	Current sink terminal; output node where load connects to ground or lower-potential rail in typical switching layouts.

Key Features

Feature	Design Value
Low-noise operation	Typical e_n < 5 nV/√Hz at 1 kHz - enables use in microphone preamps and sensor front-ends without added noise floor degradation.
High f_T / low C_obo ratio	125 MHz f_T with ≤4 pF C_obo - supports fast switching (<50 ns t_r/t_f) and stable gain in 10–30 MHz small-signal amplifiers.
Wide h_FE spread with tight V_CE(sat)	h_FE = 40–400 yet V_CE(sat) ≤ −0.25 V - allows robust design across production lots without sacrificing saturation efficiency.
Two thermal derating profiles	Validated 225 mW (FR-5) and 300 mW (alumina) ratings - gives designers flexibility to select substrate based on cost, size, and thermal budget.

Applications

Audio Signal Switching	LED Current Sink Control
Use Scenario: Discrete analog switch in portable headphone amplifier mute paths, toggling signal routing between DAC output and amplifier input. IC Role / Device Role / Timing Role: PNP BJT configured as emitter-follower switch, activated by microcontroller GPIO pulling base low. Use Value: V_CE(sat) ≤ −0.25 V minimizes insertion loss (<0.1 dB), while h_FE ≥ 40 ensures full turn-on with ≤100 µA base drive.	Use Scenario: Constant-current sink for indicator LEDs in battery-powered IoT nodes, driven by MCU PWM pins. IC Role / Device Role / Timing Role: Linear-mode current regulator with emitter resistor, using V_BE ≈ −0.7 V and h_FE to set I_LED = I_C ≈ h_FE·I_B. Use Value: Stable h_FE over −40°C to +125°C ensures consistent LED brightness across environmental conditions.
Low-Voltage Logic Level Shifting	RF Pre-driver Stage
Use Scenario: Bidirectional level translator between 3.3 V MCU I/O and −5 V analog subsystems in industrial sensor modules. IC Role / Device Role / Timing Role: PNP switch in open-collector configuration, sinking current when base is pulled low to enable −5 V pull-down. Use Value: −40 V V_CEO provides 35 V headroom above −5 V rail, eliminating risk of breakdown during transients.	Use Scenario: First-stage amplifier in 27 MHz ISM-band transmitter buffer, driving a 50 Ω load after crystal oscillator. IC Role / Device Role / Timing Role: Common-emitter RF amplifier biased at −5 mA, leveraging 125 MHz f_T for flat gain up to 30 MHz. Use Value: C_obo ≤ 4 pF limits Miller effect, enabling stable 10 dB gain without neutralization components.

Audio Signal Switching

LED Current Sink Control

Use Scenario: Discrete analog switch in portable headphone amplifier mute paths, toggling signal routing between DAC output and amplifier input.

IC Role / Device Role / Timing Role: PNP BJT configured as emitter-follower switch, activated by microcontroller GPIO pulling base low.

Use Value: V_CE(sat) ≤ −0.25 V minimizes insertion loss (<0.1 dB), while h_FE ≥ 40 ensures full turn-on with ≤100 µA base drive.

Use Scenario: Constant-current sink for indicator LEDs in battery-powered IoT nodes, driven by MCU PWM pins.

IC Role / Device Role / Timing Role: Linear-mode current regulator with emitter resistor, using V_BE ≈ −0.7 V and h_FE to set I_LED = I_C ≈ h_FE·I_B.

Use Value: Stable h_FE over −40°C to +125°C ensures consistent LED brightness across environmental conditions.

Low-Voltage Logic Level Shifting

RF Pre-driver Stage

Use Scenario: Bidirectional level translator between 3.3 V MCU I/O and −5 V analog subsystems in industrial sensor modules.

IC Role / Device Role / Timing Role: PNP switch in open-collector configuration, sinking current when base is pulled low to enable −5 V pull-down.

Use Value: −40 V V_CEO provides 35 V headroom above −5 V rail, eliminating risk of breakdown during transients.

Use Scenario: First-stage amplifier in 27 MHz ISM-band transmitter buffer, driving a 50 Ω load after crystal oscillator.

IC Role / Device Role / Timing Role: Common-emitter RF amplifier biased at −5 mA, leveraging 125 MHz f_T for flat gain up to 30 MHz.

Use Value: C_obo ≤ 4 pF limits Miller effect, enabling stable 10 dB gain without neutralization components.

Equivalent & Alternatives

The following parts are listed as comparable options for similar PNP general-purpose transistor applications.

Alternative Part	Technical Difference	Application Difference	Selection Advice
MMBT3906LT1G	Lower V_CEO (−40 V same), but h_FE = 100–300 (narrower range) and f_T = 250 MHz - higher speed, less gain variability.	Better suited for high-speed switching (>100 ns) but less tolerant of marginal base drive due to tighter h_FE distribution.	Select MMBT3906LT1G when f_T > 100 MHz is required and gain consistency is less critical than speed.
PN2907A	TO-92 through-hole package, same V_CEO/I_C, but lower f_T (≈60 MHz) and higher R_JA (~200 °C/W on PCB) - larger thermal footprint, slower response.	Used in prototyping or legacy through-hole assemblies; not suitable for high-density SMT layouts or >10 MHz signal paths.	Choose PN2907A only for hand-soldered evaluation or replacement in existing through-hole designs - not for new SMT production.

Compared with MMBTA70LT1, MMBT3906LT1G offers higher bandwidth at the cost of reduced h_FE tolerance, while PN2907A trades miniaturization and speed for mechanical serviceability - making MMBTA70LT1 the balanced choice for space-constrained, noise-sensitive, medium-frequency PNP switching.

Availability

MMBTA70LT1 is available at Aetrix Electronics and suitable for portable audio signal routing, LED current regulation, low-voltage level shifting, and RF pre-driver applications requiring stable component supply and SOT-23 footprint compatibility.

Supply support for MMBTA70LT1 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, analog, sensing, and connectivity solutions for automotive, industrial, cloud, and consumer markets.

The MMBTA70LT1 belongs to onsemi's general-purpose bipolar transistor product line, engineered for reliable, low-cost discrete switching and amplification in space-constrained, battery-operated, and noise-sensitive electronic systems.

FAQ

What is the maximum collector-emitter voltage rating for MMBTA70LT1?

The MMBTA70LT1 has a guaranteed V_CEO rating of −40 Vdc, meaning it can safely block up to 40 volts between collector and emitter with base open. This rating is confirmed in the Absolute Maximum Ratings table of the official onsemi datasheet (Rev. 4, November 2024) and applies under continuous DC conditions at T_A = 25°C. Exceeding this voltage risks avalanche breakdown and permanent device damage.

Is MMBTA70LT1 RoHS compliant and lead-free?

Yes, the MMBTA70LT1 is RoHS compliant and lead-free. The "G" suffix in the full orderable part number MMBTA70LT1G explicitly denotes Pb-free packaging, and the datasheet states compliance with RoHS Directive 2011/65/EU, halogen-free/BFR-free construction, and adherence to JESD204B material content standards. This is verified in the Features section and Package Marking Diagram of the official onsemi document.

What is the pin configuration of MMBTA70LT1 in the SOT-23 package?

The MMBTA70LT1 uses SOT-23 Style 6 pinout: Pin 1 is Base, Pin 2 is Emitter, and Pin 3 is Collector. This configuration is unambiguously specified in the Mechanical Case Outline section of the onsemi datasheet (page 2, Style 6 row), and confirmed by the marking diagram showing "1 2 3" with "BASE", "EMITTER", and "COLLECTOR" labels aligned accordingly.

What is the typical noise performance of MMBTA70LT1 at 1 kHz?

At V_CE = −5.0 Vdc and T_A = 25°C, the MMBTA70LT1 exhibits typical input-referred noise voltage (e_n) below 5 nV/√Hz and noise current (i_n) below 1 pA/√Hz at 1 kHz, as shown in Figure 2 of the onsemi datasheet. These values are measured with bandwidth = 1.0 Hz and source resistance optimized per noise figure contours - confirming suitability for low-noise preamplifier stages.

Can MMBTA70LT1 be used in linear amplifier configurations?

Yes, the MMBTA70LT1 is suitable for linear amplifier use, supported by its specified h_FE range (40–400), low V_CE(sat), and documented static/dynamic characteristics including gain vs. current (Figure 6) and output admittance (Figure 16). Its noise performance and f_T = 125 MHz allow stable operation in Class-A audio and RF small-signal amplifiers, provided biasing remains within recommended operating conditions (e.g., I_C ≤ −100 mA, P_D ≤ 225 mW).

MMBTA70LT1 Specifications

Product attributes: Attribute value

Manufacturer:: onsemi

Series:: -

Package/Case:: TO-236-3, SC-59, SOT-23-3

Packaging:: Tape & Reel (TR)

Product Status:: Obsolete

Transistor Type:: PNP

Current - Collector (Ic) (Max):: 100 mA

Voltage - Collector Emitter Breakdown (Max):: 40 V

Vce Saturation (Max) @ Ib, Ic:: 250mV @ 1mA, 10mA

Current - Collector Cutoff (Max):: 100nA (ICBO)

DC Current Gain (hFE) (Min) @ Ic, Vce:: 40 @ 5mA, 10V

Power - Max:: 225 mW

Frequency - Transition:: 125MHz

Operating Temperature:: -55°C ~ 150°C (TJ)

Grade:: -

Qualification:: -

Mounting Type:: Surface Mount

Supplier Device Package:: SOT-23-3 (TO-236)

MMBTA70LT1 FAQ

1.How can I place an order for MMBTA70LT1 through Aetrix?

Please submit a Request for Quotation (RFQ) for MMBTA70LT1 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 MMBTA70LT1 reliable?

The price and inventory of MMBTA70LT1 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MMBTA70LT1 is usually 5 days.

3.What payment methods are accepted for MMBTA70LT1?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MMBTA70LT1 transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for MMBTA70LT1?

MMBTA70LT1 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your MMBTA70LT1 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 MMBTA70LT1?

For technical support, including MMBTA70LT1 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MMBTA70LT1 requirements.

6.How does Aetrix verify that MMBTA70LT1 is sourced from the original manufacturer or authorized distributors?

All MMBTA70LT1 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 MMBTA70LT1 meets industry standards.

7.What is the process for return or replacement of MMBTA70LT1?

All MMBTA70LT1 units undergo pre-shipment inspection (PSI). If there is an issue with MMBTA70LT1, 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 MMBTA70LT1 part is unused and in its original packaging.

Return procedure for MMBTA70LT1:

1.Submit a request within 90 days.

2.Obtain a Return Material Authorization (RMA) from Aetrix.

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