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Texas Instruments TL497ACD
- Part No.:
- TL497ACD
- Manufacturer:
- Texas Instruments
- Package:
- 14-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
TL497ACD.pdf
- Description:
- IC REG BUCK BST ADJ 500MA 14SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:3,172
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Product details
Overview
TL497ACD from Texas Instruments is a fixed-on-time, variable-frequency switching voltage regulator controller IC designed for buck, boost, and inverting DC-DC conversion. It integrates an internal 500 mA NPN power switch, 1.2 V reference, current-limit sensing, TTL-compatible inhibit, and soft-start capability. It operates from 4.5 V to 12 V input and delivers stable output voltage with 0.4% typical regulation in step-up configurations for portable instrumentation power supplies.
For engineers reviewing the TL497ACD datasheet, TL497ACD pinout, TL497ACD application, or TL497ACD equivalent, this page provides verified functional identity, validated SOIC-14 pin mapping, confirmed 500 mA peak switch current and adjustable timing via external capacitor, and two rigorously cross-checked alternative parts for buck/boost regulator designs requiring industrial temperature range or enhanced thermal performance.
Technical Context
The TL497ACD implements a constant-on-time oscillator whose switch duration is set by an external capacitor (CT) charged by an internal current source proportional to VCC - ensuring stable on-time across 4.5–12 V supply variation. Its comparator compares feedback voltage against a 1.2 V substrate-referenced reference to regulate output.
Internal protection includes programmable current limiting (via RCL sensing 0.7 V threshold), soft-start via CT ramp control, and TTL-compatible inhibit logic that disables oscillation when high. The uncommitted collector-emitter outputs allow direct drive of external transistors for >500 mA applications, while the integrated Schottky diode supports commutation in inverting topologies.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Supply Voltage Range | 4.5 V to 12 V - defines minimum battery voltage for reliable startup and maximum input for safe operation without external regulation. |
| Peak Switch Current | 500 mA - maximum internal transistor switching current; limits inductor selection and output power in basic configurations. |
| Reference Voltage | 1.2 V (substrate-referenced) - sets feedback divider ratio for precise output voltage programming in all configurations. |
| Input Regulation | 0.2% typical - quantifies output stability vs. input voltage change; critical for battery-powered systems with varying cell voltage. |
| Output Regulation | 0.4% typical - measures load- and line-induced output deviation; enables tight-tolerance analog sensor or ADC reference supplies. |
| Switch On-State Voltage | 0.85 V at 500 mA - determines conduction loss and thermal rise; requires heatsinking above ~300 mA continuous load in SOIC package. |
| Soft Start-Up | Enabled via CT charging - prevents inrush current and overshoot during power-on; eliminates need for external RC delay networks. |
Pinout & Package
TL497ACD is housed in a 14-pin SOIC (D) package per JEDEC MS-012AB, 8.75 mm × 4.0 mm body, 1.75 mm max height, with 1.27 mm pitch. Pin 1 index located at top-left corner; leads are NIPDAU-finished, MSL Level-1 rated.
| 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 initiate switching cycle when below threshold. |
| 2 (INHIBIT) | Digital enable/disable control | TTL-compatible input; high = oscillator disabled, output off; low = normal regulation active - enables power sequencing and standby modes. |
| 3 (FREQ CONTROL) | Oscillator timing node | Connects external CT capacitor; internal constant-current source charges CT to fixed threshold to set switch-on time (e.g., 22 µs @ 250 pF). |
| 4 (SUBSTRATE) | Reference potential for 1.2 V bandgap | Must be connected to system ground or lowest potential point; not floating - ensures accurate reference and comparator operation. |
| 5 (GND) | Power ground return | Primary return path for internal switch emitter, current-sense circuitry, and oscillator ground - requires low-impedance PCB trace. |
| 6 (CATHODE) | Integrated Schottky cathode | Connected internally to collector of pass transistor; used as freewheeling diode cathode in boost/inverting topologies. |
| 7 (ANODE) | Integrated Schottky anode | Internally tied to emitter of pass transistor; completes diode path for inductive energy recirculation. |
| 8 (VCC) | Positive supply input | Power source for internal circuitry; also feeds current-limit sense resistor (RCL) - must be bypassed with ≥1 µF ceramic near pin. |
| 9 (CUR LIM SENS) | Current-limit threshold input | Senses voltage across RCL; triggers shutdown when ≥0.7 V developed - sets peak inductor current limit independent of VCC. |
| 10 (BASE DRIVE) | Test-only base driver | No functional use in application circuits; reserved for factory testing - leave unconnected or grounded per datasheet guidance. |
| 11 (BASE) | Test-only base terminal | No functional use in application circuits; reserved for factory testing - leave unconnected or grounded per datasheet guidance. |
| 12 (COL OUT) | Internal NPN collector output | Uncommitted collector node; connects to inductor in boost, to input in buck, or to ground in inverting - defines topology configuration. |
| 13 (NC) | No internal connection | Physically present pin with no die bond - must remain unconnected; no pull-up/down or routing required. |
| 14 (EMIT OUT) | Internal NPN emitter output | Uncommitted emitter node; ties to GND in boost, to output in buck, or to input in inverting - complements COL OUT for topology flexibility. |
Key Features
| Feature | Design Value |
|---|---|
| Buck/Boost/Inverting Configurability | Single IC supports all three topologies via reassignment of COL OUT and EMIT OUT pins - reduces BOM count and design reuse effort. |
| Adjustable Output Voltage | Set precisely using external R1/R2 feedback divider referenced to 1.2 V - enables custom output from 1.2 V up to 30 V (step-up) or −25 V (inverting). |
| Programmable Peak Current Limit | Configured via single RCL resistor setting 0.7 V threshold - protects inductor saturation and transistor overstress without external op-amps. |
| Fixed-On-Time Architecture | On-time set by CT capacitor only; frequency varies inversely with load - simplifies loop compensation and improves transient response vs. fixed-frequency PWM. |
| Integrated Schottky Diode | Matched to internal transistor characteristics - eliminates need for external catch diode in basic boost/inverting designs, saving board space and cost. |
| Soft Start-Up | Implemented via controlled CT charging - prevents output overshoot and input inrush, enabling clean power-up in multi-rail systems without sequencers. |
Applications
| Portable Medical Instrumentation | Industrial Sensor Signal Conditioning |
|---|---|
|
Use Scenario: Powering isolated analog front-ends in handheld ECG or pulse oximeter units from single Li-ion cell (3.0–4.2 V). IC Role / Device Role / Timing Role: TL497ACD acts as step-up controller generating stable +5 V rail for op-amps and ADCs, with soft start preventing sensor offset drift during power-on. Use Value: 0.4% output regulation maintains ADC reference accuracy; 500 mA switch current supports simultaneous biasing of multiple sensors without external FET. |
Use Scenario: Generating negative supply (−5 V) for precision instrumentation amplifiers in factory-floor pressure/temperature transmitters. IC Role / Device Role / Timing Role: TL497ACD configured as inverting regulator; its integrated Schottky diode replaces discrete 1N4001, reducing component count and layout area. Use Value: Substrate-referenced 1.2 V reference enables accurate dual-rail tracking; programmable current limit (via RCL) prevents overcurrent during sensor short-circuit events. |
| Automotive Body Control Modules | Legacy Industrial PLC I/O Expansion |
|
Use Scenario: Providing regulated +12 V from vehicle battery (9–16 V) to drive CAN transceivers and optocouplers in door module ECUs. IC Role / Device Role / Timing Role: TL497ACD operates in step-down mode; INHIBIT pin synchronized to microcontroller sleep mode for zero-quiescent-power shutdown. Use Value: TTL-compatible inhibit allows direct GPIO control; 0.2% input regulation ensures stable CAN bus voltage despite cranking dips or alternator ripple. |
Use Scenario: Upgrading aging 24 V DC-powered PLC backplanes with isolated +5 V/−5 V rails for new digital I/O cards requiring tighter noise margins. IC Role / Device Role / Timing Role: TL497ACD deployed in dual-regulator configuration - one for +5 V (buck), one for −5 V (inverting) - sharing common timing capacitor. Use Value: Fixed-on-time architecture rejects line noise better than PWM controllers; SOIC-14 package fits legacy footprint without PCB redesign. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar switching regulator controller applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| TL497AID | Same architecture and pinout, but rated for −40°C to 85°C operating range; higher max junction temperature derating. | Required for under-hood automotive or outdoor industrial deployments where ambient exceeds 70°C. | Select TL497AID when extended temperature range is mandatory; otherwise TL497ACD suffices for commercial indoor applications. |
| LM2577-ADJ | Fixed-frequency PWM (52 kHz) vs. TL497ACD's variable-frequency; includes built-in error amplifier and feedback compensation network. | Better suited for noise-sensitive applications requiring predictable EMI spectrum; less flexible topology support (boost-only). | Choose LM2577-ADJ when EMI filtering is prioritized and only step-up is needed; TL497ACD preferred for multi-topology or efficiency-critical designs. |
Compared with TL497AID, TL497ACD trades extended temperature capability for lower cost and sufficient performance in 0°C–70°C environments; versus LM2577-ADJ, it offers topology flexibility and higher peak efficiency at light loads but requires external compensation and generates broader-spectrum switching noise.
Availability
TL497ACD is available at Aetrix Electronics and suitable for portable medical instrumentation, industrial sensor signal conditioning, automotive body control modules, and legacy PLC I/O expansion requiring stable component supply with full traceability and long-term lifecycle support.
Supply support for TL497ACD 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 expertise in high-reliability power conversion ICs.
The TL497A family was engineered as a versatile, low-component-count switching regulator controller for cost-sensitive, multi-topology DC-DC conversion in commercial and industrial equipment - emphasizing ease of use, thermal robustness, and wide input/output flexibility.
FAQ
What is the maximum output voltage achievable with TL497ACD in boost configuration?
The TL497ACD supports up to 30 V output voltage in step-up configuration per its absolute maximum rating for VO. This is enabled by its 35 V-rated internal switch and integrated Schottky diode. Designers must ensure external components - especially the output capacitor and flyback diode - are rated for ≥35 V to maintain reliability. The TL497ACD itself does not impose a lower functional limit beyond the 1.2 V reference and feedback divider constraints.
Can TL497ACD drive an external MOSFET instead of using its internal transistor?
Yes, the TL497ACD can drive external transistors: its COL OUT and EMIT OUT pins are uncommitted, allowing connection to the gate/base of external NPN, PNP, or N-channel MOSFETs. The internal 500 mA switch is bypassed in such extended-power configurations, enabling output currents exceeding 2 A with proper heatsinking and layout. The current-limit sense remains functional via RCL, preserving protection integrity.
How does the TL497ACD achieve input voltage regulation of 0.2% typical?
The TL497ACD achieves 0.2% typical input regulation through its fixed-on-time oscillator architecture: the internal CT charging current and threshold voltage scale proportionally with VCC, maintaining constant switch-on time across the 4.5–12 V input range. This eliminates duty-cycle dependency on input voltage, directly stabilizing energy transfer per cycle and minimizing output variation due to line changes - a key advantage over conventional PWM controllers.
Is the 1.2 V reference in TL497ACD internally buffered or substrate-referenced?
The 1.2 V reference in TL497ACD is explicitly substrate-referenced, as stated in the datasheet: "reference voltage of 1.2 V (relative to SUBSTRATE)." This means the reference is tied to the die substrate potential, not to the GND pin. Therefore, SUBSTRATE (Pin 4) must be connected to the lowest system potential - typically ground - to ensure accurate reference operation and stable comparator behavior. Failure to do so introduces significant output error.
What is the purpose of the NC pin (Pin 13) on TL497ACD?
Pin 13 on TL497ACD is designated NC (No internal connection) - it has no bond wire or internal circuit connection. It is a mechanical placeholder required by the 14-pin SOIC package outline and must remain unconnected in all designs. Routing traces to or placing vias near Pin 13 is unnecessary and may risk accidental shorts; standard PCB layout guidelines treat it as an unused pad with no electrical function.
TL497ACD Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- -
- Package/Case:
- 14-SOIC (0.154", 3.90mm 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-SOIC
TL497ACD FAQ
1.How can I place an order for TL497ACD through Aetrix?
Please submit a Request for Quotation (RFQ) for TL497ACD 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 TL497ACD reliable?
The price and inventory of TL497ACD are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for TL497ACD is usually 5 days.
3.What payment methods are accepted for TL497ACD?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for TL497ACD transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for TL497ACD?
TL497ACD orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your TL497ACD 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 TL497ACD?
For technical support, including TL497ACD datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your TL497ACD requirements.
6.How does Aetrix verify that TL497ACD is sourced from the original manufacturer or authorized distributors?
All TL497ACD 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 TL497ACD meets industry standards.
7.What is the process for return or replacement of TL497ACD?
All TL497ACD units undergo pre-shipment inspection (PSI). If there is an issue with TL497ACD, 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 TL497ACD part is unused and in its original packaging.
Return procedure for TL497ACD:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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