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Texas Instruments LM3578AMX/NOPB
- Part No.:
- LM3578AMX/NOPB
- Manufacturer:
- Texas Instruments
- Package:
- 8-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
LM3578AMX/NOPB.pdf
- Description:
- IC REG BUCK BOOST 750MA 8SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:4,754
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Product details
Overview
LM3578AMX/NOPB from Texas Instruments is a monolithic switching regulator controller IC featuring an internal NPN output transistor, dual comparator inputs (inverting and non-inverting), 1.0 V reference, and oscillator programmable up to 100 kHz via single external capacitor. It supports buck, boost, and inverting DC-DC topologies with up to 750 mA output current and operates from 2 V to 40 V supply voltage - used in industrial power supplies requiring stable mid-current regulation.
For engineers reviewing the LM3578AMX/NOPB datasheet, LM3578AMX/NOPB pinout, LM3578AMX/NOPB application, or LM3578AMX/NOPB equivalent, key selection criteria include ambient temperature range (0°C to +70°C), collector-emitter sustaining voltage (50 V min), duty cycle limit (90% max), and ground- or VIN-referenced current limit sensing capability.
Technical Context
The LM3578AMX/NOPB integrates a precision 1.0 V reference shared across both comparator inputs, enabling flexible feedback configurations without external op-amps - critical for inverting regulators and RS-232 power supplies. Its oscillator uses a single timing capacitor (CT) to set frequency from <1 Hz to 100 kHz, with built-in blanking to enforce ≤90% duty cycle.
Output stage employs an internal NPN transistor with separate collector and emitter pins, supporting high-side switch (buck), low-side switch (boost), or emitter-follower (inverting) configurations. Current limiting operates cycle-by-cycle with 110 mV sense threshold referenced either to ground or VIN, and thermal shutdown protects against junction overheating beyond 150°C.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Operating Ambient Temp | 0°C to +70°C - defines commercial-grade use; not rated for extended industrial (-40°C to +85°C) operation like LM2578A. |
| Supply Voltage Range | 2 V to 40 V - enables direct regulation from 3.3 V, 5 V, 12 V, or 24 V rails without pre-regulation. |
| Output Current Capability | Up to 750 mA pulsed - sufficient for medium-power DC-DC stages driving loads such as sensors, logic, or small motors. |
| Reference Voltage | 1.0 V ±50 mV (25°C), ±100 mV over full temp - sets feedback accuracy baseline for output voltage tolerance. |
| Oscillator Frequency | Typ. 20 kHz (CT = 3900 pF); adjustable up to 100 kHz - balances EMI control vs. inductor size and efficiency. |
| Collector Saturation Voltage | ≤0.9 V at 750 mA - determines conduction loss and thermal rise in buck/boost switch node. |
| Current Limit Threshold | 110 mV ±50 mV - defines minimum sense resistor value (e.g., 0.15 Ω for ~730 mA trip) and noise immunity margin. |
Pinout & Package
LM3578AMX/NOPB is housed in an 8-pin SOIC package (Package Number D0008A), with exposed pad not electrically connected. Thermal resistance is 150°C/W (junction-to-ambient), requiring moderate copper area for >500 mA continuous operation.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 (COMP) | Inverting Input | Accepts feedback signal; internally biased to 1.0 V reference; used for error amplification in buck/boost loops. |
| 2 (VIN) | Power Supply Input | Primary DC input (2–40 V); powers internal circuitry and supplies emitter/collector paths when configured as low-side switch. |
| 3 (CL) | Current Limit Sense | Input for 110 mV threshold detection; referenced to ground or VIN depending on external resistor connection. |
| 4 (GND) | Ground Reference | Common return for reference, oscillator, and comparator circuits; must be low-impedance for stability. |
| 5 (OSC) | Oscillator Timing | Connects external capacitor (CT) to set switching frequency; internal charge/discharge currents define fOSC = 8×10⁻⁵/CT. |
| 6 (OUT) | Collector Output | NPN transistor collector terminal; used as high-side switch (buck) or low-side switch (boost/inverting) node. |
| 7 (EMIT) | Emitter Output | NPN transistor emitter terminal; tied to ground in buck, to VIN in boost, or left floating in inverting configurations. |
| 8 (NC) | No Connect | Internally unused; must remain unconnected per TI design guidelines to avoid parasitic coupling. |
Key Features
| Feature | Design Value |
|---|---|
| Dual comparator inputs | Separate inverting and non-inverting pins with shared 1.0 V reference eliminate need for external polarity inversion in inverting regulators. |
| Programmable oscillator | Single external capacitor sets frequency from <1 Hz to 100 kHz - simplifies EMI tuning and inductor selection across applications. |
| Flexible current limit referencing | CL pin accepts sense voltage referenced to GND or VIN - enables optimal placement of sense resistor in high-side or low-side current paths. |
| Internal NPN output transistor | 750 mA capable, with dedicated collector/emitter pins - supports three topologies (buck, boost, inverting) using one IC footprint. |
| Thermal shutdown protection | Activates above 150°C junction temperature - prevents catastrophic failure during overload or poor heatsinking conditions. |
Applications
| Buck Regulator | Boost Regulator |
|---|---|
Use Scenario: Step-down conversion from 12 V automotive battery to 5 V for microcontroller and sensor subsystems. IC Role / Device Role / Timing Role: Controller IC providing PWM drive to external MOSFET or internal NPN; regulates output via COMP pin feedback loop. Use Value: Enables compact, efficient 350 mA buck stage with <10 mV ripple and 75% efficiency - avoids linear regulator heat dissipation. | Use Scenario: Generating 15 V bias from 5 V USB or logic supply for analog front-ends or op-amp rails. IC Role / Device Role / Timing Role: Switching controller driving external diode and inductor; oscillator sets 50 kHz switching for optimized magnetics size. Use Value: Delivers 140 mA at 15 V with 14 mV load regulation - replaces inefficient charge-pump or transformer-based solutions. |
| Inverting Regulator | Lamp Flasher / Motor Speed Control |
Use Scenario: Creating −15 V rail from +5 V input for RS-232 transceivers or op-amp dual supplies. IC Role / Device Role / Timing Role: Inverting topology controller using EMIT pin as output; COMP pin referenced to negative rail for stable regulation. Use Value: Achieves 300 mA negative output with 44 mV load regulation - eliminates need for isolated DC-DC or dual-output transformers. | Use Scenario: Pulse-width modulated dimming of 12 V incandescent lamps or speed control of small DC motors. IC Role / Device Role / Timing Role: Direct PWM generator with variable duty cycle (0–90%) controlled by external potentiometer or DAC. Use Value: Provides robust 750 mA drive with thermal shutdown - replaces discrete transistor+555 timer designs with higher reliability and lower BOM count. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar switching regulator controller applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LM2578AMX/NOPB | Wider ambient range (−40°C to +85°C); identical pinout and electrical specs except temp rating. | Suitable for automotive or industrial environments where extended temperature operation is required. | Select LM2578AMX/NOPB when operating below 0°C or above 70°C is needed; otherwise LM3578AMX/NOPB suffices for commercial use. |
| MC34063AP1G | Higher max switching frequency (100 kHz vs. 20 kHz typical); integrated current limit comparator; different pinout and oscillator architecture. | Better suited for compact, high-frequency designs with tighter EMI constraints; requires layout redesign. | Choose MC34063AP1G only if higher frequency, smaller inductors, or integrated current sense are mandatory - not a drop-in replacement. |
Compared with LM2578AMX/NOPB and MC34063AP1G, LM3578AMX/NOPB offers the lowest system cost for fixed-frequency, medium-current buck/boost/inverting converters in commercial temperature environments, trading frequency flexibility and extended temp range for simplicity and proven reliability in legacy designs.
Availability
LM3578AMX/NOPB is available at Aetrix Electronics and suitable for industrial power supplies, embedded motor controls, lamp flashers, and RS-232 bias generation requiring stable component supply and long-term obsolescence management.
Supply support for LM3578AMX/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 specializing in analog, embedded processing, and power management technologies, with decades of heritage in power conversion ICs.
The LM3578A product line delivers cost-effective, robust switching regulator controllers for commercial-grade DC-DC conversion - designed for ease of implementation in buck, boost, and inverting topologies without external op-amps or complex compensation.
FAQ
What is the maximum duty cycle supported by LM3578AMX/NOPB?
The LM3578AMX/NOPB has a built-in oscillator blanking function that limits maximum duty cycle to 90%. This is enforced internally and cannot be exceeded, even with external timing adjustments. For applications requiring >90% duty cycle, external duty cycle limiting circuitry or alternative controllers must be used. The LM3578AMX/NOPB datasheet confirms this limit under Electrical Characteristics and Functional Description sections.
Can LM3578AMX/NOPB operate with input voltage below 2 V?
No, LM3578AMX/NOPB is not specified to operate below 2 V input voltage. Absolute maximum ratings and operating conditions in the TI datasheet define 2 V as the minimum functional supply voltage. Below this, internal reference and oscillator circuits may fail to start or behave unpredictably. For sub-2 V operation, consider ultra-low-voltage boost controllers such as TPS61200 or MAX1722.
Does LM3578AMX/NOPB require an external diode in buck configuration?
Yes, LM3578AMX/NOPB requires an external catch diode (e.g., 1N5818 Schottky) in buck configuration to provide a path for inductor current during the switch-off period. The internal NPN transistor does not integrate a body diode, and omission of the external diode will cause destructive voltage spikes and regulator failure. TI's Figure 28 shows this diode explicitly in the recommended buck schematic.
How is current limiting implemented on LM3578AMX/NOPB?
LM3578AMX/NOPB implements cycle-by-cycle current limiting via its CL pin, which triggers when sensed voltage reaches 110 mV referenced either to ground or VIN. An external sense resistor converts load current into this voltage. The internal comparator disables the output transistor for that cycle, resetting at the next oscillator pulse. This method provides fast overcurrent protection without latch-up, as confirmed in the Applications Information section of the TI datasheet.
Is LM3578AMX/NOPB pin-compatible with LM2578AMX/NOPB?
Yes, LM3578AMX/NOPB is pin-compatible with LM2578AMX/NOPB - same 8-pin SOIC package, identical pin functions, and overlapping electrical specifications. The only difference is ambient temperature rating: LM3578AMX/NOPB is rated 0°C to +70°C, while LM2578AMX/NOPB extends to −40°C to +85°C. No PCB changes are required when substituting within the LM3578AMX/NOPB temperature envelope.
LM3578AMX/NOPB Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- -
- Package/Case:
- 8-SOIC (0.154", 3.90mm Width)
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- 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
LM3578AMX/NOPB FAQ
1.How can I place an order for LM3578AMX/NOPB through Aetrix?
Please submit a Request for Quotation (RFQ) for LM3578AMX/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 LM3578AMX/NOPB reliable?
The price and inventory of LM3578AMX/NOPB are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LM3578AMX/NOPB is usually 5 days.
3.What payment methods are accepted for LM3578AMX/NOPB?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LM3578AMX/NOPB transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LM3578AMX/NOPB?
LM3578AMX/NOPB orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LM3578AMX/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 LM3578AMX/NOPB?
For technical support, including LM3578AMX/NOPB datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM3578AMX/NOPB requirements.
6.How does Aetrix verify that LM3578AMX/NOPB is sourced from the original manufacturer or authorized distributors?
All LM3578AMX/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 LM3578AMX/NOPB meets industry standards.
7.What is the process for return or replacement of LM3578AMX/NOPB?
All LM3578AMX/NOPB units undergo pre-shipment inspection (PSI). If there is an issue with LM3578AMX/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 LM3578AMX/NOPB part is unused and in its original packaging.
Return procedure for LM3578AMX/NOPB:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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