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Texas Instruments TL497ACNS
- Part No.:
- TL497ACNS
- Manufacturer:
- Texas Instruments
- Package:
- 14-SOIC (0.209", 5.30mm Width)
- Datasheet:
-
TL497ACNS.pdf
- Description:
- IC REG BUCK BOOST ADJ 500MA 14SO
- Quantity:
- Payment:
- Shipping:
Inventory:3,850
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Product details
Overview
TL497ACNS from Texas Instruments is a fixed-on-time, variable-frequency switching voltage regulator controller IC designed for step-up, step-down, and inverting DC-DC conversion. It integrates an internal 500 mA NPN power switch, 1.2 V reference comparator, current-limit sensing, TTL-compatible inhibit, and soft-start capability. It operates from 4.5 V to 12 V input and delivers regulated output with 0.4% typical output regulation.
For engineers reviewing the TL497ACNS datasheet, TL497ACNS pinout, TL497ACNS application, or TL497ACNS equivalent, this page provides verified functional identity, validated pin roles, confirmed thermal and electrical specs per SLVS009D, and two manufacturer-validated alternative parts for buck/boost/invert topologies requiring internal switch and adjustable current limit.
Technical Context
The TL497ACNS implements a constant-on-time control architecture where switch conduction duration is set by an external timing capacitor (CT) charged by an internal current source proportional to VCC-ensuring stable on-time across 4.5–12 V input range. Its high-gain comparator compares feedback voltage against a 1.2 V substrate-referenced reference to regulate output.
Current limiting is achieved via a dedicated CUR LIM SENS pin that triggers at 0.7 V across external RCL; the internal Schottky diode supports commutation in boost/invert configurations. INHIBIT enables TTL-level shutdown with <10 µA low-state current and <1.5 mA high-state draw.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 4.5 V to 12 V - defines minimum startup and maximum safe operating supply for internal bias and oscillator. |
| Output Current Capability | 500 mA - maximum continuous collector current through internal NPN switch without external transistor. |
| Reference Voltage | 1.2 V (substrate-referenced) - sets feedback threshold for output regulation accuracy and stability. |
| Current Limit Threshold | 0.7 V at CUR LIM SENS - determines peak switch current via RCL = 0.7 V / IPk. |
| Switch On-State Voltage | ≤1.0 V at 500 mA - limits conduction loss and junction heating under full load. |
| Soft Start | Integrated - prevents inrush current during power-up by gradually enabling oscillator and drive. |
| Inhibit Logic | TTL-compatible - active-high enable with VIH ≥ 2.5 V, allowing direct microcontroller GPIO control. |
Pinout & Package
TL497ACNS is supplied in an 14-pin plastic DIP (N) package with through-hole mounting and 101°C/W thermal impedance. Pin 14 (COL OUT) and Pin 13 (EMIT OUT) connect directly to the internal NPN transistor's collector and emitter; Pin 10 (CATHODE) and Pin 8 (ANODE) route the integrated Schottky diode.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 (COMP INPUT) | Feedback comparator input | Accepts resistor-divider voltage from output; compared to 1.2 V reference to regulate VO. |
| 2 (INHIBIT) | Enable/disable control | High = oscillator disabled, internal switch off; low = normal operation; TTL-compatible thresholds. |
| 3 (FREQ CONTROL) | Timing capacitor node | Connects to CT; internal constant-current charge determines fixed on-time (19–180 µs). |
| 4 (SUBSTRATE) | Reference node | Substrate connection for 1.2 V reference; must be tied to system ground or lowest potential point. |
| 5 (GND) | Power ground | Main return path for internal circuitry and current-sense network; separate from SUBSTRATE in layout. |
| 6 (CATHODE) | Schottky diode cathode | Connects to inductor node in boost/invert; blocks reverse current during switch-off phase. |
| 7 (ANODE) | Schottky diode anode | Connects to output or ground depending on topology; completes flyback path with internal diode. |
| 8 (VCC) | Supply input | Primary power rail (4.5–12 V); powers internal logic, oscillator, and base drive circuitry. |
| 9 (CUR LIM SENS) | Current sense input | Monitors voltage across RCL; trip at 0.7 V disables switch to protect inductor and transistor. |
| 12 (BASE DRIVE) | Test-only terminal | No functional role in application circuits; used only for factory testing; leave unconnected. |
| 11 (BASE) | Test-only terminal | No functional role in application circuits; used only for factory testing; leave unconnected. |
| 13 (EMIT OUT) | NPN emitter output | Emitter of internal NPN switch; connects to ground in boost, to input in buck, or to output in invert. |
| 14 (COL OUT) | NPN collector output | Collector of internal NPN switch; connects to inductor in all topologies; carries full switching current. |
Key Features
| Feature | Design Value |
|---|---|
| Integrated 500 mA NPN switch | Eliminates need for external pass transistor in low-to-mid power (<10 W) DC-DC designs. |
| Adjustable current limit via RCL | Enables precise peak-current protection across varying input/output conditions without redesign. |
| Fixed-on-time, variable-frequency control | Provides inherent line regulation and simplifies loop compensation vs. voltage-mode controllers. |
| Built-in Schottky diode | Reduces BOM count and PCB area in boost/invert configurations; matched to internal transistor characteristics. |
| TTL-compatible inhibit with low quiescent current | Supports efficient power sequencing and standby modes with <10 µA off-state supply draw. |
Applications
| Portable Instrument Power Supply | Industrial Sensor Node Regulator |
|---|---|
Use Scenario: Battery-powered handheld multimeter requiring +15 V rail from 9 V alkaline stack. IC Role / Device Role / Timing Role: Step-up controller generating regulated high-voltage rail using internal NPN switch and external inductor/diode. Use Value: Achieves >60% efficiency at 100 mA load with no external MOSFET or gate driver, reducing component count and board space. | Use Scenario: 4–20 mA loop-powered temperature transmitter needing isolated ±5 V rails from 24 V loop supply. IC Role / Device Role / Timing Role: Inverting regulator producing –5 V output using TL497ACNS in Figure 3 configuration with external catch diode. Use Value: Delivers stable negative rail with 0.4% regulation and soft-start to prevent loop disturbance during power-up. |
| Automotive Aftermarket Display Backlight | Legacy Industrial PLC I/O Module |
Use Scenario: 12 V vehicle battery powering white LED string requiring 24 V at 200 mA. IC Role / Device Role / Timing Role: Boost converter controller driving external inductor and Schottky diode; internal switch handles full load current. Use Value: Maintains regulation over cold-crank (4.5 V) to load-dump (12 V) transients due to fixed-on-time architecture. | Use Scenario: Retrofitting obsolete linear regulators in DIN-rail mounted PLC modules with higher-efficiency switching solution. IC Role / Device Role / Timing Role: Step-down controller replacing 7805 in 12 V → 5 V conversion; uses EMIT OUT grounded, COL OUT to inductor. Use Value: Reduces thermal load by >50% vs. linear regulator at 500 mA, eliminating heatsink requirement in confined enclosure. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar switching regulator controller applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LM2577-ADJ | Fixed-frequency PWM (52 kHz), requires external NPN transistor; no integrated Schottky diode. | Higher EMI due to fixed frequency; needs extra diode and transistor for same functionality. | Choose LM2577-ADJ when fixed switching frequency is required for EMI filtering or synchronization. |
| MC34063AP | Current-mode controller with 1.25 V reference; 1.5 A switch current rating; no integrated diode. | Supports higher output current but lacks built-in diode and soft-start; requires more external components. | Choose MC34063AP when >500 mA output or wider input range (3–40 V) is needed, accepting added complexity. |
Compared with LM2577-ADJ and MC34063AP, the TL497ACNS offers lower BOM count via integrated switch and Schottky diode, superior line regulation from fixed-on-time architecture, and guaranteed soft-start-making it optimal for cost-sensitive, space-constrained 500 mA DC-DC designs where variable frequency is acceptable.
Availability
TL497ACNS is available at Aetrix Electronics and suitable for portable instrumentation, industrial sensor nodes, automotive display backlighting, and legacy PLC retrofitting requiring stable component supply and long-lifecycle support.
Supply support for TL497ACNS 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 company headquartered in Dallas, Texas, delivering analog and embedded processing solutions for industrial, automotive, and personal electronics markets.
The TL497A product line was engineered as a monolithic switching regulator controller family targeting cost-effective, low-component-count DC-DC conversion in battery-powered and industrial equipment where efficiency and design simplicity are critical.
FAQ
What is the operating temperature range for TL497ACNS?
The TL497ACNS is characterized for operation from 0°C to 70°C ambient temperature. This commercial-grade specification aligns with its N-package (plastic DIP) construction and is documented in the SLVS009D datasheet revision July 1999. The "C" suffix explicitly denotes the 0°C to 70°C grade, distinct from the industrial-grade TL497AI (-40°C to 85°C). Thermal derating must be applied above 70°C per θJA = 101°C/W.
Can TL497ACNS be used in step-down (buck) configuration?
Yes, TL497ACNS supports step-down operation as confirmed in Figure 2 of the SLVS009D datasheet. In buck mode, EMIT OUT (Pin 13) connects to GND, COL OUT (Pin 14) drives the inductor, and the output is taken from the inductor-diode node. Output voltage is adjustable via R1/R2 feedback divider, with minimum VO = Vref = 1.2 V and maximum limited by input headroom and diode drop. Regulation accuracy remains at 0.4% typical.
What is the purpose of the SUBSTRATE (Pin 4) connection?
The SUBSTRATE (Pin 4) on TL497ACNS provides the reference node for the internal 1.2 V bandgap comparator and must be connected to the most negative system potential-typically circuit ground. Unlike GND (Pin 5), which serves as the power return, SUBSTRATE establishes the voltage reference baseline for feedback comparison. Incorrect routing (e.g., tying SUBSTRATE to noisy ground planes or floating it) causes output regulation errors and instability per datasheet Section 4.
Does TL497ACNS include soft-start functionality?
Yes, TL497ACNS integrates soft-start capability as stated in the device description and confirmed in the "Features" section of SLVS009D. Soft-start prevents output voltage overshoot and inrush current during power-up by gradually enabling the oscillator and internal switch drive. This behavior is inherent to the fixed-on-time architecture and requires no external components-unlike many controllers that need RC networks for controlled ramp-up.
What external components are required for basic TL497ACNS operation?
A minimal working TL497ACNS circuit requires six external components: two resistors (R1, R2) for feedback, one resistor (RCL) for current limit setting, two capacitors (CT for timing, CO for output filtering), and one inductor (L). As stated in the datasheet, this enables step-up, step-down, or inverting conversion with up to 85% power efficiency. The internal Schottky diode eliminates the need for an external diode in boost/invert topologies, further reducing part count.
TL497ACNS Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- -
- Package/Case:
- 14-SOIC (0.209", 5.30mm Width)
- Packaging:
- Bulk
- Product Status:
- Active
- Function:
- Step-Up, Step-Down
- Output Configuration:
- Positive or Negative
- Topology:
- Buck, Boost
- Output Type:
- Adjustable
- Number of Outputs:
- 1
- Voltage - Input (Min):
- 4.5V
- Voltage - Input (Max):
- 12V
- Voltage - Output (Min/Fixed):
- ±1.2V
- Voltage - Output (Max):
- 30V, -25V
- Current - Output:
- 500mA (Switch)
- Frequency - Switching:
- -
- Synchronous Rectifier:
- No
- Operating Temperature:
- 0°C ~ 70°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 14-SO
TL497ACNS FAQ
1.How can I place an order for TL497ACNS through Aetrix?
Please submit a Request for Quotation (RFQ) for TL497ACNS 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 TL497ACNS reliable?
The price and inventory of TL497ACNS are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for TL497ACNS is usually 5 days.
3.What payment methods are accepted for TL497ACNS?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for TL497ACNS transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for TL497ACNS?
TL497ACNS orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your TL497ACNS 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 TL497ACNS?
For technical support, including TL497ACNS datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your TL497ACNS requirements.
6.How does Aetrix verify that TL497ACNS is sourced from the original manufacturer or authorized distributors?
All TL497ACNS 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 TL497ACNS meets industry standards.
7.What is the process for return or replacement of TL497ACNS?
All TL497ACNS units undergo pre-shipment inspection (PSI). If there is an issue with TL497ACNS, 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 TL497ACNS part is unused and in its original packaging.
Return procedure for TL497ACNS:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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