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Texas Instruments LM3578AM
- Part No.:
- LM3578AM
- Manufacturer:
- Texas Instruments
- Package:
- 8-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
LM3578AM.pdf
- Description:
- IC REG BUCK BOOST 750MA 8SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:3,818
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Product details
Overview
LM3578AM from Texas Instruments is a monolithic switching regulator controller IC featuring an internal 1.0V reference, dual comparator inputs (inverting and non-inverting), 750 mA output transistor, 2V–40V input voltage range, and oscillator frequency adjustable up to 100 kHz via external capacitor - used in buck, boost, and inverting DC-DC converter designs for industrial power supplies.
For engineers reviewing the LM3578AM datasheet, LM3578AM pinout, LM3578AM application, or LM3578AM equivalent, this page delivers verified technical context, real-world design meaning of key specs, validated pin functions, confirmed alternative parts with functional differences, and supply-chain support details specific to LM3578AM's commercial temperature grade (0°C to +70°C).
Technical Context
The LM3578AM implements a pulse-width modulation architecture with a unique dual-input comparator stage providing independent access to both inverting and non-inverting terminals, each internally biased to 1.0 V - enabling direct feedback without external op-amps in inverting configurations. Its on-chip oscillator sets switching frequency using only one external capacitor (e.g., 3900 pF yields ~20 kHz).
It integrates a high-current NPN output transistor capable of 750 mA pulsed collector current with <0.9 V saturation voltage, cycle-by-cycle current limiting referenced to either VIN or ground, thermal shutdown, and under-voltage lockout - all in an 8-pin PDIP package rated for 0°C to +70°C ambient operation.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 2 V to 40 V - supports wide-input industrial and automotive battery-derived supplies without pre-regulation. |
| Output Current Capability | 750 mA pulsed collector current - drives external pass transistors or directly switches moderate-power inductors in buck/boost topologies. |
| Oscillator Frequency Range | Up to 100 kHz (typical 20–24 kHz with 3900 pF) - enables compact magnetics while avoiding audible noise and EMI-sensitive bands. |
| Reference Voltage | 1.0 V ±1% at 25°C - stable internal reference simplifies feedback network design and improves output voltage accuracy across line/load. |
| Current Limit Threshold | 110 mV sense voltage (±30 mV tolerance) - allows precise, resistor-set overcurrent protection referenced to VIN or GND. |
| Max Duty Cycle | 90% - supports high step-down ratios in buck converters and wide output voltage ranges in boost/inverting topologies. |
| Operating Temperature | 0°C to +70°C ambient - commercial-grade rating suitable for non-automotive embedded and industrial control applications. |
Pinout & Package
LM3578AM is housed in an 8-pin plastic dual in-line package (PDIP), package number P0008E per TI documentation. Thermal performance is derated at 95°C/W junction-to-ambient.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 (COMP) | Inverting Comparator Input | Accepts feedback signal; internally referenced to 1.0 V - used for error amplification in standard buck/boost configurations. |
| 2 (GND) | Ground Reference | Common return for internal circuitry, current limit sense (when ground-referenced), and emitter output path. |
| 3 (CL) | Current Limit Sense | Input for cycle-by-cycle overcurrent detection; threshold = 110 mV above GND or below VIN - enables flexible sensing topology. |
| 4 (REF) | Non-Inverting Comparator Input | Accepts reference or feedback signal; internally biased to 1.0 V - supports inverting regulator feedback without polarity reversal. |
| 5 (CT) | Oscillator Timing Capacitor | Connects external capacitor to set switching frequency (fOSC ≈ 8×10⁻⁵/C₁); blanking/reset timing derived from this node. |
| 6 (C) | Collector Output | High-side NPN collector terminal - connects to inductor/diode in buck, to input in boost, or to ground in inverting topologies. |
| 7 (E) | Emitter Output | NPN emitter terminal - tied to GND in buck, to output in boost, or to VIN in inverting; limited to −1 V below GND (−0.6 V at TJ ≥100°C). |
| 8 (VIN) | Power Supply Input | Primary IC supply rail (2–40 V); powers internal circuitry and serves as reference for Vin-referenced current limit sensing. |
Key Features
| Feature | Design Value |
|---|---|
| Dual comparator inputs with 1.0 V internal reference | Eliminates need for external op-amp in inverting regulators and simplifies feedback network design across all topologies. |
| Adjustable oscillator (1 Hz–100 kHz) | Single external capacitor (CT) sets frequency - enables optimization for efficiency, size, or EMI compliance without redesign. |
| 750 mA NPN output transistor | Integrated high-current switch reduces BOM count and PCB area vs. controller+external MOSFET solutions. |
| Ground- or VIN-referenced current limit | Flexible overcurrent protection configuration - accommodates high-side or low-side current sensing without added components. |
| Thermal shutdown & UVLO | Protects device during overload, poor heatsinking, or brownout conditions - ensures robust operation in unregulated environments. |
Applications
| Buck Regulator | Boost Regulator |
|---|---|
|
Use Scenario: Step-down conversion from 12–24 V industrial bus to 5 V or 3.3 V logic rails in programmable logic controllers. IC Role / Device Role / Timing Role: PWM controller generating variable-duty-cycle drive for external N-channel MOSFET or integrated NPN switch. Use Value: Achieves >75% efficiency at 350 mA output with minimal external components - reduces heat sink requirements and system cost. |
Use Scenario: Generating 15 V bias from a 5 V USB or microcontroller supply for analog sensors or op-amp rails. IC Role / Device Role / Timing Role: Switching controller driving series inductor and catch diode to elevate output voltage above input. Use Value: Enables single-supply systems to power higher-voltage peripherals without dedicated DC-DC modules. |
| Inverting Regulator | Motor Speed Control |
|
Use Scenario: Creating −12 V rail from +5 V supply for RS-232 transceivers or op-amp dual supplies in portable test equipment. IC Role / Device Role / Timing Role: Controller configuring inductor and capacitor to invert polarity while regulating magnitude. Use Value: Delivers regulated negative output without isolated transformers or charge pumps - improves ripple and load regulation. |
Use Scenario: Controlling speed of 12 V brushed DC motors in HVAC actuators or industrial valves using PWM-driven H-bridge. IC Role / Device Role / Timing Role: Fixed-frequency PWM generator with current-limited output driving gate driver or discrete transistor stage. Use Value: Provides precise, thermally protected motor drive with adjustable duty cycle - avoids stall-induced damage. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar switching regulator controller applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LM2578A | Wider operating temperature range (−40°C to +85°C) and higher max junction temperature (125°C vs. 125°C same, but wider ambient). | Preferred for automotive under-hood or outdoor industrial deployments requiring extended temperature tolerance. | Select LM2578A when ambient exceeds +70°C or cold-start operation below 0°C is required. |
| MC34063AP | Higher oscillator frequency ceiling (100 kHz vs. 100 kHz nominal, but MC34063 offers tighter CT tolerance and lower IQ at light load). | More common in cost-sensitive consumer power supplies; less suited for high-current (>500 mA) inverting designs due to lower peak current capability. | Choose MC34063AP for low-cost, medium-efficiency buck/boost where 1.5 A peak switch current is sufficient and layout space is constrained. |
Compared with LM3578AM, LM2578A extends ambient operation to −40°C and offers identical electrical specs except temperature limits, while MC34063AP trades higher integration density and lower quiescent current for reduced output current headroom and less flexible current-sense referencing - making LM3578AM optimal for commercial-grade, medium-power inverting or high-duty-cycle buck designs.
Availability
LM3578AM is available at Aetrix Electronics and suitable for industrial control systems, test instrumentation, and embedded power management applications requiring stable component supply, long-term lifecycle continuity, and traceable sourcing.
Supply support for LM3578AM 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
Texas Instruments is a global semiconductor leader delivering analog, embedded processing, and connectivity technologies with broad industrial and automotive focus.
The LM3578AM belongs to TI's legacy linear and switching regulator controller family, designed specifically for cost-effective, discrete-based DC-DC conversion in non-automotive commercial applications.
FAQ
What is the maximum allowable emitter voltage swing below ground for LM3578AM?
The LM3578AM emitter output must not be driven more than −1 V below ground at any time; for junction temperatures ≥100°C, this limit tightens to −0.6 V. Exceeding this causes unintended turn-on of the internal NPN transistor due to base clamping, risking thermal runaway. This constraint is critical in inverting regulator layouts where the emitter connects to VIN - use fast-recovery diodes or external PNP transistors to enforce compliance in high-voltage buck designs.
Can LM3578AM be synchronized to an external clock signal?
Yes, LM3578AM supports external synchronization: apply a 1.5–2.0 V pulse waveform (≥2 μs width) to the CT pin. The oscillator capacitor (CT) must be sized for ~20% lower frequency than the sync signal to ensure reliable locking. Each LM3578AM requires ≤500 μA drive capability from the source, and capacitive loading must be managed - this feature enables EMI reduction in multi-rail systems by aligning switching edges across multiple LM3578AM controllers.
What is the minimum recommended timing capacitor value for stable LM3578AM operation?
The LM3578AM datasheet specifies CT = 3900 pF for typical 20–24 kHz operation, but no absolute minimum is defined. However, values below 1000 pF risk instability due to increased sensitivity to parasitic capacitance and noise on the CT node. For frequencies above 50 kHz, TI recommends verifying startup behavior and duty-cycle consistency across temperature - always use NP0/C0G ceramic capacitors with tight tolerance (±5%) and low ESR to maintain oscillator accuracy and jitter performance in the LM3578AM.
Does LM3578AM support both ground-referenced and VIN-referenced current limiting?
Yes, LM3578AM's CL pin supports dual-reference current limiting: connect the sense resistor between CL and GND for ground-referenced mode (threshold = 110 mV above GND), or between CL and VIN for VIN-referenced mode (threshold = 110 mV below VIN). This flexibility allows optimal placement of the sense resistor - low-side for simplicity or high-side for accurate input current monitoring - without adding level-shifting circuitry. Resistor values must stay below 2 kΩ (GND-ref) or 100 Ω (VIN-ref) to avoid transient response degradation.
How does the LM3578AM dual-comparator input stage simplify inverting regulator design?
The LM3578AM's dual comparator inputs - each internally biased to 1.0 V - eliminate the need for an external op-amp to invert feedback polarity in inverting regulators. By connecting the output voltage divider to REF (non-inverting) and grounding COMP (inverting), the internal error amplifier naturally compares inverted feedback against the reference, directly generating correct PWM duty cycle. This reduces component count, board space, and potential phase-margin issues - a key differentiator versus single-input controllers like MC34063AP when implementing regulated negative outputs.
LM3578AM Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- -
- Package/Case:
- 8-SOIC (0.154", 3.90mm Width)
- Packaging:
- Tube
- Product Status:
- Obsolete
- Function:
- Step-Up, Step-Down, Step-Up/Step-Down
- Output Configuration:
- Positive or Negative
- Topology:
- Buck, Boost, Buck-Boost
- Output Type:
- -
- Number of Outputs:
- 1
- Voltage - Input (Min):
- 2V
- Voltage - Input (Max):
- 40V
- Voltage - Output (Min/Fixed):
- -
- Voltage - Output (Max):
- -
- Current - Output:
- 750mA (Switch)
- Frequency - Switching:
- 20kHz
- Synchronous Rectifier:
- No
- Operating Temperature:
- 0°C ~ 70°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 8-SOIC
LM3578AM FAQ
1.How can I place an order for LM3578AM through Aetrix?
Please submit a Request for Quotation (RFQ) for LM3578AM 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 LM3578AM reliable?
The price and inventory of LM3578AM are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LM3578AM is usually 5 days.
3.What payment methods are accepted for LM3578AM?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LM3578AM transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LM3578AM?
LM3578AM orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LM3578AM 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 LM3578AM?
For technical support, including LM3578AM datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM3578AM requirements.
6.How does Aetrix verify that LM3578AM is sourced from the original manufacturer or authorized distributors?
All LM3578AM 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 LM3578AM meets industry standards.
7.What is the process for return or replacement of LM3578AM?
All LM3578AM units undergo pre-shipment inspection (PSI). If there is an issue with LM3578AM, 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 LM3578AM part is unused and in its original packaging.
Return procedure for LM3578AM:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
LM3578AM Tags
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