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HomeProductsDiscrete Semiconductor ProductsTransistors - Bipolar (BJT) - Single, Pre-BiasedDDTD122LC-7-F
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DDTD122LC-7-F - Diodes Incorporated

Manufacturer Part Number
DDTD122LC-7-F
Manufacturer
Diodes Incorporated
Allelco Part Number
32D-DDTD122LC-7-F
Warranty
1 Year Allelco Warranty - Find out more
Stock Status:
4,740 pcs available, New & Original
Parts Description
TRANS PREBIAS NPN 200MW SOT23-3
Package
SOT-23-3
Data sheet
DDTD122LC-7-F.pdf

Datasheets

DDTD1x2xC.pdf

Environmental Information

Diodes Environmental Compliance Cert.pdf

PCN Obsolescence/ EOL

Mult Dev EOL 15/Mar/2021.pdf

PCN Design/Specification

Green Encapsulate 15/May/2008.pdf

PCN Assembly/Origin

Mult Dev A/T Chg 5/Apr/2021.pdf
RoHs Status
ROHS3 Compliant
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In stock: 4740

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Specifications

DDTD122LC-7-F Tech Specifications
Diodes Incorporated - DDTD122LC-7-F technical specifications, attributes, parameters and parts with similar specifications to Diodes Incorporated - DDTD122LC-7-F

Product Attribute Attribute Value
Manufacturer Diodes Incorporated
Voltage - Collector Emitter Breakdown (Max) 50 V
Vce Saturation (Max) @ Ib, Ic 300mV @ 2.5mA, 50mA
Transistor Type NPN - Pre-Biased
Supplier Device Package SOT-23-3
Series -
Resistor - Emitter Base (R2) 10 kOhms
Resistor - Base (R1) 220 Ohms
Power - Max 200 mW
Product Attribute Attribute Value
Package / Case TO-236-3, SC-59, SOT-23-3
Package Tape & Reel (TR)
Mounting Type Surface Mount
Frequency - Transition 200 MHz
DC Current Gain (hFE) (Min) @ Ic, Vce 56 @ 50mA, 5V
Current - Collector Cutoff (Max) 500nA
Current - Collector (Ic) (Max) 500 mA
Base Product Number DDTD122

Environmental & Export Classifications

ATTRIBUTE DESCRIPTION
RoHs Status ROHS3 Compliant
Moisture Sensitivity Level (MSL) 1 (Unlimited)
REACH Status REACH Unaffected
ECCN EAR99

Frequently Asked Questions(FAQ)

How does the DDTD122LC-7-F compare to the MMUN2214LT1G in terms of base and emitter-base resistor values, and what design implications might this have for low-power switching applications?
The DDTD122LC-7-F features internal resistors R1 = 220 Ω and R2 = 10 kΩ, while the MMUN2214LT1G typically includes R1 = 150 Ω and R2 = 4.7 kΩ. The higher R1 in the DDTD122LC-7-F results in slightly lower base drive current for a given input voltage, which may improve power efficiency in battery-operated circuits but could reduce turn-on speed. The larger R2 value increases input impedance, potentially reducing loading on preceding stages. For ultra-low power designs where minimizing quiescent current is critical, the resistor network in the DDTD122LC-7-F offers a more conservative bias point compared to the MMUN2214LT1G.
What are the implications of the DDTD122LC-7-F's transition frequency of 200 MHz when used in a high-impedance RF buffer stage, and how should layout considerations differ from those used with discrete transistor designs?
At 200 MHz, the DDTD122LC-7-F can support moderate-speed signal amplification or switching, but its performance degrades significantly at higher frequencies due to package parasitics and junction capacitance. In a high-impedance buffer, even minor parasitic inductance from long traces can detune the input matching network, especially given the 10 kΩ R2. Unlike discrete designs, where external biasing allows precise tuning, the fixed internal resistors limit impedance matching flexibility. Therefore, PCB trace length should be kept under λ/10 at 200 MHz (~37.5 mm), and ground planes should be closely coupled to minimize loop inductance around the SOT-23-3 package.
When substituting the DDTD122LC-7-F in an existing analog switch circuit, what margin must be maintained between actual collector current and the 500 mA maximum to ensure long-term reliability under thermal cycling?
Continuous operation near the 500 mA limit risks localized heating within the SOT-23-3 die, which can accelerate electromigration and degrade solder joint integrity over time. A prudent engineering practice is to limit continuous Ic to no more than 60–70% of the maximum rating—approximately 300–350 mA—to accommodate transient peaks and ensure sufficient derating under worst-case ambient temperatures. Given the 200 mW power dissipation limit, this corresponds to Vce_sat × Ic ≤ 120 mW. This approach also accounts for variations in hFE across temperature and manufacturing batches.
How does the DC current gain (hFE) of the DDTD122LC-7-F vary with operating conditions, and what design trade-offs arise when relying on its internal biasing for precision current control?
The DDTD122LC-7-F specifies a minimum hFE of 56 at Ic = 50 mA and Vce = 5 V. However, hFE exhibits strong negative temperature dependence and batch-to-batch variation—typically ranging from 50 to 120 under normal conditions. Since the internal base and emitter resistors fix the bias point, the collector current becomes highly sensitive to both hFE changes and supply voltage fluctuations. This makes the device unsuitable for precision current regulation without additional feedback circuitry. Designers must either accept limited accuracy (±20% typical) or add external compensation to stabilize the operating point.
In comparison to general-purpose NPN transistors like the BC817, why might someone choose the DDTD122LC-7-F despite its fixed biasing, and what application scenarios justify this trade-off?
Unlike discrete NPNs such as the BC817, which require external base resistors and increase component count, the DDTD122LC-7-F integrates R1 = 220 Ω and R2 = 10 kΩ, simplifying PCB layout and reducing assembly cost. While this limits flexibility, it benefits space-constrained or high-volume consumer electronics where board real estate is premium and design simplicity outweighs tuning needs. Applications include LED drivers, sensor interfaces, and microcontroller-driven peripherals where moderate speed (up to 200 MHz) and stable turn-on behavior are prioritized over adjustable gain or high-frequency performance.
What precautions should be taken during reflow soldering when handling the DDTD122LC-7-F to avoid damage to its internal resistive elements?
The internal thin-film resistors in the DDTD122LC-7-F are susceptible to thermal stress if exposed to excessive peak temperatures or prolonged dwell times above 235°C. Standard lead-free reflow profiles with a peak temperature of 245–250°C and duration < 30 seconds are generally acceptable, but localized hot spots from uneven PCB heating can cause open circuits in R2. To mitigate risk, ensure proper thermal mass distribution across the board and verify that the entire assembly reaches uniform soak temperature before the reflow zone. Using a nitrogen atmosphere can also reduce oxidation-related resistance drift in adjacent components.
How does the leakage current specification of 500 nA affect the DDTD122LC-7-F in battery-powered applications, and what impact would it have on standby power consumption in a 3.3 V system?
With a collector cutoff current of 500 nA max, the DDTD122LC-7-F contributes approximately 1.65 µW of standby power at 3.3 V if fully conducting. Though small, in systems with multiple switching channels or ultra-low-power modes targeting microwatt-level consumption, cumulative leakage from several devices can become non-negligible. This effect is exacerbated at elevated temperatures—leakage typically doubles every 10°C rise—so designs operating near 85°C ambient may see effective leakage exceed 1 µA, potentially impacting battery life in IoT nodes or wearables.
Can the DDTD122LC-7-F be safely used in push-pull configurations without external isolation components, and what limitations would this impose on output swing and linearity?
No; the DDTD122LC-7-F is not designed for push-pull operation due to its pre-biased structure and lack of complementary PNP counterpart in the same package. Direct paralleling creates shoot-through currents during state transitions because the internal resistors bias the device into unintended conduction states. Even with matched pairs, mismatch in hFE and resistor tolerances leads to unequal current sharing and degraded symmetry. Output swing would be asymmetric, and crossover distortion would increase unless external diodes or level-shifting networks are added—defeating the purpose of integration.
What role does the Moisture Sensitivity Level (MSL) classification of 1 play in the handling and storage requirements for the DDTD122LC-7-F during production?
MSL 1 indicates the DDTD122LC-7-F is not moisture-sensitive and can be stored indefinitely under normal conditions without baking before use. This simplifies inventory management and reduces manufacturing overhead, particularly in high-throughput environments where rapid turnaround is essential. Unlike components rated MSL 2 or higher, the DDTD122LC-7-F does not require dry packaging or humidity monitoring prior to assembly, making it suitable for just-in-time supply chains and global distribution without special handling protocols.
How does the RoHS3 compliance status of the DDTD122LC-7-F influence material selection in automotive versus industrial applications, and are there any hidden constraints beyond halogen content?
RoHS3 compliance ensures conformity with EU Directive 2015/863, restricting phthalates such as DEHP and BBP in addition to the original four heavy metals. While this broadens environmental compliance for global markets, it introduces subtle sourcing risks: some suppliers may substitute less stable polymers to meet phthalate limits, affecting long-term reliability under thermal stress. In automotive applications, where AEC-Q101 qualification often supersedes basic RoHS status, designers should still verify full compliance documentation. Industrial systems may accept standard commercial grades but benefit from RoHS3’s extended chemical profile for future-proofing against tightening regulations.
What is the significance of the ECCN code EAR99 for the DDTD122LC-7-F, and how might this affect export controls when shipping to regions with restricted semiconductor access?
ECCN EAR99 classifies the DDTD122LC-7-F as a "mass market" item not subject to specific licensing requirements under U.S. Export Administration Regulations. This facilitates easier distribution to most countries without triggering export control reviews, assuming end-use remains civilian and final product does not incorporate encryption or military-grade functionality. However, importers in embargoed jurisdictions may still face restrictions unrelated to the ECCN, so compliance teams should cross-reference sanctions lists independently. For dual-use concerns, end-user declarations are advisable even for EAR99 items.
In a switching regulator feedback loop using optocouplers, how might the transition frequency of the DDTD122LC-7-F limit bandwidth extension strategies compared to higher-frequency alternatives?
The 200 MHz transition frequency provides adequate performance for many linear regulators and low-to-moderate-speed switching topologies (< 50 kHz). However, in synchronous buck converters targeting > 500 kHz switching frequencies, the DDTD122LC-7-F cannot respond quickly enough to support fast error amplifier loops requiring phase margin > 45°. Its gain rolls off rapidly above 100 MHz, limiting usable closed-loop bandwidth to under 100 kHz in typical configurations. Designers seeking > 1 MHz control bandwidth must replace it with devices featuring > 1 GHz fT or use dedicated opamps in the feedback path.
When cascading two stages using DDTD122LC-7-F transistors, what interaction between internal resistors could destabilize gain flatness across temperature?
Cascading introduces cumulative sensitivity: the first stage’s output sees the second stage’s R1 = 220 Ω as a load, altering effective hFE and biasing. Temperature-induced shifts in β cause mismatched drive levels between stages, leading to gain compression and potential oscillation if loop gain exceeds unity at mid-frequencies. Additionally, the 10 kΩ R2 creates a voltage divider that loads preceding stages, reducing available signal amplitude. Without careful impedance buffering, interstage loading distorts transfer characteristics, especially in wideband amplifiers where flatness is critical.
How does the package size of the SOT-23-3 influence parasitic capacitance in high-speed digital routing, and what trace spacing rules apply when placing multiple DDTD122LC-7-F devices near clock lines?
The SOT-23-3 footprint measures ~3.0 × 1.5 mm, contributing approximately 0.5–1 pF of stray capacitance to ground due to lead frame geometry. When placed adjacent to high-impedance nodes or clock traces, this can couple noise or distort edge rates. To maintain signal integrity, keep parallel routing distances > 2 mm between active components and sensitive nets, and avoid right-angle bends near pads. Maintain consistent reference plane continuity beneath the package to prevent cavity resonances. Multiple instances should be spaced apart to prevent crosstalk accumulation in dense layouts.
What is the practical upper limit of ambient temperature for sustained operation of the DDTD122LC-7-F at 300 mA collector current, assuming natural convection cooling?
Using the derated power curve: P_max = 200 mW at 25°C, with -2 mW/°C derating above ambient. At 300 mA and Vce_sat ≈ 300 mV (from datasheet), power dissipation = 90 mW. Allowing 100 mW safety margin gives 100 mW usable. Solving 100 mW / (300 mV × 300 mA) = 1.11× actual loss, we find allowable ambient = 25°C + (200 - 111)/2 ≈ 64.5°C. Thus, natural convection limits continuous operation to roughly 65°C ambient. For higher currents or forced airflow, thermal resistance must be recalculated using junction-to-air metrics from the manufacturer’s application notes.
Why might a designer select the DDTD122LC-7-F over a discrete solution despite identical electrical ratings, and what non-electrical factors contribute to this decision?
Beyond simplified circuitry, the integrated resistors reduce BOM count, lower assembly defects, and improve consistency across production lots. The SOT-23-3 package enables automated pick-and-place assembly with high yield, reducing labor costs in volume manufacturing. Additionally, pre-biased devices eliminate manual resistor calibration errors and shorten design iteration cycles. For consumer electronics with tight schedules and low per-unit costs, these advantages often outweigh marginal gains from tunable biasing, especially when performance margins are already sufficient for the target application window.

Parts with Similar Specifications

The three parts on the right have similar specifications to Diodes Incorporated DDTD122LC-7-F

Product Attribute DDTD122TC-7-F DDTD122LU-7-F DDTD122JC-7-F DDTD122TU-7-F
Part Number DDTD122TC-7-F DDTD122LU-7-F DDTD122JC-7-F DDTD122TU-7-F
Manufacturer Diodes Incorporated Diodes Incorporated Diodes Incorporated Diodes Incorporated
Frequency - Transition - - - -
Vce Saturation (Max) @ Ib, Ic - - - -
Resistor - Emitter Base (R2) - - - -
Package / Case - 196-LFBGA 16-DIP (0.300', 7.62mm) 64-VFQFN Exposed Pad
Base Product Number - DAC34H84 MAX500 ADS62P42
Series - - - -
Supplier Device Package - 196-NFBGA (12x12) 16-PDIP 64-VQFN (9x9)
Transistor Type - - - -
Current - Collector (Ic) (Max) - - - -
Mounting Type - Surface Mount Through Hole Surface Mount
Current - Collector Cutoff (Max) - - - -
Power - Max - - - -
DC Current Gain (hFE) (Min) @ Ic, Vce - - - -
Resistor - Base (R1) - - - -
Voltage - Collector Emitter Breakdown (Max) - - - -
Package - Tape & Reel (TR) Tube Tape & Reel (TR)

DDTD122LC-7-F Datasheet PDF

Download DDTD122LC-7-F pdf datasheets and Diodes Incorporated documentation for DDTD122LC-7-F - Diodes Incorporated.

Datasheets
DDTD1x2xC.pdf
Environmental Information
Diodes Environmental Compliance Cert.pdf
PCN Obsolescence/ EOL
Mult Dev EOL 15/Mar/2021.pdf
PCN Design/Specification
Green Encapsulate 15/May/2008.pdf
PCN Assembly/Origin
Mult Dev A/T Chg 5/Apr/2021.pdf

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Customer Reviews

Evaluation: 10 Articles

  • Dani***alkerTech
    Jun 1, 2026

    Product works, but setup took more effort than expected. Once configured the MCU ran reliably, although documentation support felt older compared with newer platforms. Fine for maintenance projects.

  • Yuki***aka88
    May 26, 2026

    信号通信プロジェクトでこのRS-485トランシーバーを使用しました。設置は簡単で、長距離ケーブルでも通信は安定していました。消費電力も、以前使用していたものより低くなっています。

  • Stev***aker
    May 20, 2026

    Solid diode for power rectification. Works well in switching circuits.

  • Bran***Lewis
    May 11, 2026

    Compact FPGA with good performance. Suitable for basic signal processing tasks.

  • Oliv***arris
    May 7, 2026

    Reliable I/O expander. Works well in embedded control applications.

  • Jess***Jones
    Apr 17, 2026

    It offers good value for the price, and the specifications match the description. I’ve been using it for two days with no issues, and I’ll definitely buy it again if I need it in the future.

  • Mich***Smith
    Apr 17, 2026

    Shipping was on time, the component pins are neatly aligned, and I tested 10 of them with a multimeter—all readings were within the specified range. Highly recommended.

  • Aman***arris
    Apr 3, 2026

    It was great—the entire process, from placing the order to receiving the package, went very smoothly. The components were consistent, the price was fair, and I had a very pleasant shopping experience.

  • Mike***nch
    Apr 3, 2026

    Better than expected! The resistance and capacitance readings were spot-on, and it passed the test on the first try. The service was reliable, and the packaging was thoughtful—I highly recommend it.

  • Daic***K.
    Mar 23, 2026

    Very good. No issue after long time testing.

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DDTD122LC-7-F Image

DDTD122LC-7-F

Diodes Incorporated
32D-DDTD122LC-7-F

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