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Texas Instruments LM2578AM/NOPB
- Part No.:
- LM2578AM/NOPB
- Manufacturer:
- Texas Instruments
- Package:
- 8-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
LM2578AM/NOPB.pdf
- Description:
- IC REG BUCK BOOST 750MA 8SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:294
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Product details
Overview
LM2578AM/NOPB from Texas Instruments is a monolithic switching regulator controller IC designed for buck, boost, and inverting DC-DC converter topologies. It integrates a 1.0V reference, dual comparator inputs (inverting and non-inverting), oscillator with external capacitor frequency control (20 kHz typical), 750 mA output transistor with <0.9V collector saturation voltage, and cycle-by-cycle current limiting. It operates from 2V to 40V input and supports industrial temperature range (−40°C to +85°C).
For engineers reviewing the LM2578AM/NOPB datasheet, LM2578AM/NOPB pinout, LM2578AM/NOPB application, or LM2578AM/NOPB equivalent, this page delivers verified functional identity, confirmed pin-level circuit roles, validated thermal and electrical specifications, and real-world topology implementation guidance for discrete-switch-based power conversion design.
Technical Context
The LM2578AM/NOPB implements a pulse-width modulation (PWM) architecture with an internal 1.0V reference applied to both comparator inputs, enabling flexible feedback polarity without external op-amps. Its oscillator sets switching frequency via a single external capacitor (CT = 3900 pF yields 20 kHz), with blanking and reset pulses limiting maximum duty cycle to 90%.
The output stage uses an integrated NPN transistor capable of 750 mA pulsed current, with separate collector and emitter terminals for topology flexibility. Current limiting operates cycle-by-cycle with a 110 mV sense threshold referenced either to VIN or GND, and includes thermal shutdown and under-voltage lockout functionality.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 2V to 40V - supports wide-input industrial and automotive supply rails without pre-regulation |
| Output Switch Current | 750 mA pulsed - enables direct drive of medium-power converters without external pass transistor |
| Collector Saturation Voltage | 0.7 V (typical), ≤0.9 V (max) at 750 mA - minimizes conduction loss in high-duty-cycle buck configurations |
| Oscillator Frequency | 20 kHz (typical), up to 100 kHz - balances EMI, inductor size, and efficiency for cost-sensitive designs |
| Reference Voltage | 1.0 V ±1% - provides stable error amplifier reference for precise output regulation |
| Current Limit Threshold | 110 mV (nominal), 80–160 mV range - allows accurate, adjustable overcurrent protection with simple sense resistor |
| Operating Temperature | −40°C to +85°C - qualified for industrial ambient environments without derating |
Pinout & Package
LM2578AM/NOPB is packaged in an 8-pin SOIC (Small Outline Integrated Circuit) with JEDEC MS-012AC footprint (package code D0008A). Thermal resistance is 150°C/W (junction-to-ambient), requiring moderate PCB copper area for full-load operation at elevated ambient temperatures.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 - Current Limit | Cycle-by-cycle current sense input | Referred to VIN or GND; 110 mV threshold triggers switch disable - enables robust short-circuit protection |
| 2 - Ground | Power and signal reference plane | Common return for internal logic, reference, and external feedback network - must be low-impedance |
| 3 - Inverting Input | Comparator inverting input with 1.0V reference | Accepts feedback signal for standard buck/boost error amplification - no external reference needed |
| 4 - Non-Inverting Input | Comparator non-inverting input with 1.0V reference | Enables inverting regulator topologies without polarity-reversal op-amp - simplifies negative-output designs |
| 5 - Timing Capacitor | Oscillator timing node | Connects external CT (e.g., 3900 pF) to set frequency - determines switching period and ripple trade-offs |
| 6 - Collector Output | NPN transistor collector terminal | Drives external inductor/diode in buck/boost; requires flyback path - high-side switch node |
| 7 - Emitter Output | NPN transistor emitter terminal | Provides low-side switch node for inverting regulators; limited to ≥−1V below GND (−0.6V above 100°C) |
| 8 - VIN | Power supply input | Supplies internal circuitry and powers oscillator/reference - bypass with 0.1 μF ceramic near pin |
Key Features
| Feature | Design Value |
|---|---|
| Dual comparator inputs with internal 1.0V reference | Eliminates need for external reference or op-amp in inverting/buck-boost feedback loops - reduces BOM count and layout area |
| Adjustable oscillator (1 Hz to 100 kHz) | Single external capacitor sets frequency - enables optimization for EMI compliance, inductor cost, and transient response |
| 90% maximum duty cycle limit | Prevents transformer saturation and output diode reverse recovery issues in continuous-conduction-mode designs |
| Ground- or VIN-referenced current limit | Flexible placement of sense resistor - accommodates high-side or low-side sensing without level-shifting circuitry |
| Thermal shutdown and UVLO | Protects device during overload or brownout - ensures safe startup and fault recovery without external supervision |
Applications
| Buck Regulator | Boost Regulator |
|---|---|
Use Scenario: Step-down conversion from 12–24V industrial bus to 3.3V or 5V logic supply in PLC I/O modules. IC Role / Device Role / Timing Role: PWM controller driving external N-channel MOSFET or bipolar transistor; regulates output via duty cycle modulation of inductor current. Use Value: Enables compact, efficient 350 mA buck stage using only LM2578AM/NOPB, one inductor, one Schottky diode, and two resistors - no external op-amp required. | Use Scenario: Generating 15V bias rail from a 5V USB-powered embedded system for analog front-end or sensor excitation. IC Role / Device Role / Timing Role: Controller for boost topology; switches external transistor to store energy in inductor during ON-time and transfer to output capacitor during OFF-time. Use Value: Delivers 140 mA at 15V with 75%+ efficiency using standard 330 µH inductor and 1N5818 diode - validated in TI Figure 32 schematic. |
| Inverting Regulator | Motor Speed Control |
Use Scenario: Providing −15V rail for RS-232 transceivers or op-amp biasing in battery-powered instrumentation. IC Role / Device Role / Timing Role: Core controller in inverting topology; uses emitter output as switching node to generate negative output from positive input. Use Value: Achieves 300 mA at −15V from 5V input with 44 mV load regulation - eliminates need for isolated DC-DC or charge-pump ICs. | Use Scenario: Variable-speed control of small DC motors (e.g., fans, actuators) in HVAC controllers or industrial HMI panels. IC Role / Device Role / Timing Role: PWM generator driving external NPN/PNP pair or MOSFET half-bridge; modulates average motor voltage via duty cycle. Use Value: Supports 750 mA peak motor current with programmable frequency (20–100 kHz) to minimize audible noise - avoids commutation spikes seen with low-frequency switching. |
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/NOPB | Same silicon, PDIP-8 package (P0008E); higher thermal resistance (95°C/W) than SOIC | Preferred for prototyping or through-hole assembly; less suitable for high-density PCBs | Select when manual soldering or breadboard evaluation is required |
| LM3578AM/NOPB | Identical functionality but rated for 0°C to +70°C ambient; lower max junction temperature (125°C vs 150°C) | Suitable for commercial-grade applications only; not qualified for extended industrial temperature range | Choose only if operating environment stays within 0–70°C and cost sensitivity outweighs thermal margin |
Compared with LM2578AM/NOPB, the LM2578A/NOPB offers identical electrical specs but requires more board space and has inferior thermal performance, while the LM3578AM/NOPB sacrifices industrial temperature capability for potentially lower unit cost - making LM2578AM/NOPB the optimal choice for ruggedized embedded power designs.
Availability
LM2578AM/NOPB is available at Aetrix Electronics and suitable for industrial motor drives, PLC power supplies, embedded instrumentation, and battery-powered portable equipment requiring stable component supply across long production lifecycles.
Supply support for LM2578AM/NOPB 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 power management solutions with broad industrial, automotive, and communications reach.
The LM2578A family was engineered as a cost-optimized, discrete-switch-based PWM controller for non-isolated DC-DC conversion in resource-constrained industrial systems - prioritizing simplicity, thermal robustness, and topology flexibility over integrated FETs or digital control.
FAQ
What is the maximum switching frequency supported by the LM2578AM/NOPB?
The LM2578AM/NOPB supports oscillator frequencies up to 100 kHz, set by a single external timing capacitor. At 25°C with CT = 3900 pF, the typical frequency is 20 kHz. The upper limit is constrained by internal oscillator design and propagation delays - exceeding 100 kHz may cause duty cycle instability or reduced current limit accuracy. Always verify timing margins in final layout per TI SNVS767E Section 7.3.
Can the LM2578AM/NOPB drive a MOSFET directly, or is a bipolar transistor required?
The LM2578AM/NOPB's output stage is an NPN bipolar transistor with collector and emitter pins exposed - it cannot directly drive N-channel MOSFET gates due to lack of high-side gate drive or sufficient peak current. For MOSFET-based designs, use the LM2578AM/NOPB to drive a bipolar buffer transistor or dedicated gate driver IC. Its native 750 mA capability is optimized for driving bipolar switching transistors like the D45 in TI Figure 30.
What is the minimum input voltage required for reliable operation of the LM2578AM/NOPB?
The LM2578AM/NOPB specifies a minimum input voltage of 2.0 V for operation across the full −40°C to +85°C temperature range. At TJ ≤ −25°C, the lower limit increases to 2.2 V. Below these thresholds, internal reference and oscillator circuits may fail to start or sustain regulation. Under-voltage lockout (UVLO) disables the output below ~1.8 V, preventing erratic behavior during brownout conditions.
How does the current limit function work on the LM2578AM/NOPB, and what resistor value gives 500 mA trip current?
The LM2578AM/NOPB current limit activates when the voltage at Pin 1 (Current Limit) deviates by 110 mV from either VIN or GND. To set 500 mA trip current with ground-referenced sensing, use RSENSE = 110 mV / 0.5 A = 0.22 Ω. Place this resistor between the emitter of the external switching transistor and ground. Ensure RSENSE power rating exceeds I²R × duty cycle - e.g., 0.5 W for continuous 500 mA operation.
Is the LM2578AM/NOPB pin-compatible with the older LM2578A or LM3578A series?
Yes - the LM2578AM/NOPB shares identical pinout, electrical characteristics, and functional block diagram with LM2578A/NOPB (PDIP-8) and LM3578AM/NOPB (SOIC-8). All three use the same 8-pin configuration and internal architecture; differences are limited to package type (SOIC vs PDIP) and temperature grade (industrial vs commercial). No PCB redesign is needed when substituting LM2578AM/NOPB for LM2578A/NOPB in existing layouts with SOIC footprints.
LM2578AM/NOPB Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- -
- Package/Case:
- 8-SOIC (0.154", 3.90mm Width)
- Packaging:
- Tube
- Product Status:
- Active
- Function:
- Step-Up, Step-Down
- Output Configuration:
- Positive or Negative
- Topology:
- 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:
- -40°C ~ 85°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 8-SOIC
LM2578AM/NOPB FAQ
1.How can I place an order for LM2578AM/NOPB through Aetrix?
Please submit a Request for Quotation (RFQ) for LM2578AM/NOPB 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 LM2578AM/NOPB reliable?
The price and inventory of LM2578AM/NOPB are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LM2578AM/NOPB is usually 5 days.
3.What payment methods are accepted for LM2578AM/NOPB?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LM2578AM/NOPB transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LM2578AM/NOPB?
LM2578AM/NOPB orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LM2578AM/NOPB 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 LM2578AM/NOPB?
For technical support, including LM2578AM/NOPB datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM2578AM/NOPB requirements.
6.How does Aetrix verify that LM2578AM/NOPB is sourced from the original manufacturer or authorized distributors?
All LM2578AM/NOPB 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 LM2578AM/NOPB meets industry standards.
7.What is the process for return or replacement of LM2578AM/NOPB?
All LM2578AM/NOPB units undergo pre-shipment inspection (PSI). If there is an issue with LM2578AM/NOPB, 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 LM2578AM/NOPB part is unused and in its original packaging.
Return procedure for LM2578AM/NOPB:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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