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Analog Devices Inc./Maxim Integrated MAX728CCK
- Part No.:
- MAX728CCK
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Package:
- TO-220-5
- Datasheet:
-
MAX728CCK.pdf
- Description:
- IC REG BUCK 3.3V 2A TO220-5
- Quantity:
- Payment:
- Shipping:
Inventory:1,496
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Product details
Overview
MAX728CCK from Maxim Integrated is a monolithic, bipolar, PWM step-down DC-DC regulator with fixed 3.3V output, 2A on-chip power switch, and 100kHz switching frequency. It operates from an 8V–40V input range, features cycle-by-cycle current limiting, and is housed in a 5-pin TO-220 package for high-current industrial power conversion.
For engineers reviewing the MAX728CCK datasheet, MAX728CCK pinout, MAX728CCK application, or MAX728CCK equivalent, this part supports stable 3.3V/2A distributed power delivery in high-voltage bus systems where thermal management, transient response, and minimal external component count are critical selection criteria.
Technical Context
The MAX728CCK implements a classic buck topology with integrated oscillator, error amplifier, and 2A bipolar power switch. Its fixed 3.3V output is set by internal feedback, and SENSE pin monitoring enables both regulation and low-VOUT frequency scaling to prevent sub-microsecond on-times.
It uses cycle-by-cycle current limiting for overcurrent and short-circuit protection, and its VC pin supports external TTL clock synchronization (115–170kHz) or compensation network connection. The device requires no external power switch or controller logic.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Voltage | Fixed 3.3V ±2.0% over full temperature and line/load range - eliminates need for external resistor divider. |
| Input Voltage Range | 8V to 40V - supports direct connection to unregulated industrial or automotive battery buses without pre-regulation. |
| Switching Frequency | 100kHz (±15%) - balances EMI control, inductor size, and efficiency for medium-power applications. |
| Current Limit | 2.6A typical - provides robust short-circuit protection while sustaining 2A continuous output under thermal limits. |
| Quiescent Current | 8.5mA - enables low-noise operation without significant standby power penalty in always-on systems. |
| Package | 5-pin TO-220 (staggered leads) - thermally optimized for heatsink mounting; case connected to GND for low-noise grounding. |
| Operating Temperature | 0°C to +70°C - validated for commercial-grade embedded power supplies with standard PCB thermal relief. |
Pinout & Package
MAX728CCK is supplied in a 5-pin TO-220 package with staggered leads and case electrically connected to GND. Standard lead form is staggered; straight-lead variants require factory consultation.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VIN | Input Power Supply | Supplies internal circuitry and collector of on-chip bipolar switch; must be bypassed with ≥220µF low-ESR capacitor. |
| VSW | Switch Output | Emitter of internal bipolar switch; swings up to 35V below GND; connects to inductor in buck topology. |
| GND | Ground Reference | Reference for internal bandgap and error amplifier; case is internally tied to GND - requires low-impedance PCB ground plane. |
| VC | Error Amplifier Output | Compensation node; swing limited to –0.7V to +5.8V; supports external sync clock (115–170kHz) or RC compensation. |
| SENSE | Feedback & Current Sense Input | Directly connected to VOUT; sets regulation point and reduces oscillator frequency when VOUT drops below 2.0V (prevents instability). |
Key Features
| Feature | Design Value |
|---|---|
| Integrated 2A bipolar power switch | Eliminates external MOSFET and gate driver; reduces BOM count and layout complexity in compact 3.3V supplies. |
| Fixed 3.3V output voltage | Removes external feedback resistors - improves accuracy, stability, and production consistency across units. |
| Cycle-by-cycle current limiting | Provides immediate shutdown during overload or short-circuit events without requiring external sense resistors or comparators. |
| Low 8.5mA quiescent current | Minimizes no-load power loss in battery-backed or energy-sensitive systems without sacrificing regulation performance. |
| TO-220 thermal package with GND-connected case | Enables direct mechanical and electrical attachment to heatsinks, reducing thermal resistance and simplifying EMI filtering. |
Applications
| Industrial Distributed Power | High-Voltage Bus Converter |
|---|---|
|
Use Scenario: Converting 24V or 36V factory bus voltage to regulated 3.3V for PLC I/O modules and sensor interfaces. IC Role / Device Role / Timing Role: Primary step-down regulator delivering 2A continuous 3.3V with fast transient response to load steps from digital logic. Use Value: Eliminates need for external switch and controller; 100kHz frequency allows use of small, off-the-shelf 100µH inductors. |
Use Scenario: Powering microcontroller-based telemetry nodes from 40V telecom or railway auxiliary rails. IC Role / Device Role / Timing Role: Standalone buck converter providing isolated 3.3V rail with built-in current limiting and thermal robustness. Use Value: Withstands 40V input transients; 2.6A current limit protects against downstream fault propagation without added circuitry. |
| Multiple-Output Buck System | Legacy Embedded Power Supply |
|
Use Scenario: Serving as secondary 3.3V regulator in multi-rail systems where 5V and 3.3V outputs are derived from common high-voltage input. IC Role / Device Role / Timing Role: Dedicated 3.3V channel synchronized via VC pin to avoid beat-frequency noise with other regulators. Use Value: VC pin accepts external TTL clock (115–170kHz), enabling deterministic switching alignment across multiple MAX72x devices. |
Use Scenario: Replacing aging linear regulators in legacy industrial controllers requiring 3.3V/2A with improved efficiency. IC Role / Device Role / Timing Role: Drop-in replacement for obsolete discrete-switcher designs - same TO-220 footprint and pinout. Use Value: Reduces heat sink size by >60% vs. linear solution; maintains compatibility with existing PCB layouts and thermal design. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar step-down regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| MAX728ECK | Wider operating temperature range (–40°C to +85°C); otherwise identical electrical specs and pinout. | Suitable for extended-temperature environments such as outdoor enclosures or vehicle under-hood locations. | Select MAX728ECK when ambient temperature exceeds +70°C or storage conditions include sub-zero exposure. |
| LM2596T-3.3 | CMOS-based; lower quiescent current (5mA); 150kHz switching; requires external diode; different pinout and compensation. | Better light-load efficiency but lacks integrated bipolar switch robustness and cycle-by-cycle current limiting. | Choose LM2596T-3.3 only if board redesign is acceptable and higher-frequency operation with external components is preferred. |
Compared with MAX728ECK and LM2596T-3.3, the MAX728CCK offers guaranteed commercial-temperature operation with fully integrated bipolar switching and proven ruggedness in high-noise industrial settings - making it optimal for cost-sensitive, volume-manufactured equipment where layout and thermal simplicity are prioritized.
Availability
MAX728CCK is available at Aetrix Electronics and suitable for industrial distributed power, high-voltage bus conversion, and legacy embedded power supply applications requiring stable component supply and long-term sourcing continuity.
Supply support for MAX728CCK 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
Maxim Integrated (now part of Analog Devices) is a semiconductor company specializing in high-performance analog, mixed-signal, and power management ICs for industrial, communications, and computing markets.
The MAX727/MAX728/MAX729 family was designed as monolithic, high-current buck regulators targeting space-constrained, high-reliability power conversion where integration, thermal performance, and fault protection are essential.
FAQ
What is the output voltage tolerance of the MAX728CCK over temperature and line/load conditions?
The MAX728CCK has a nominal output voltage of 3.3V with a tolerance of ±2.0% across the full operating temperature range (0°C to +70°C) and input voltage range (8V to 40V). At +25°C, the tighter tolerance is ±0.5%. This specification ensures reliable logic-level compliance for 3.3V microcontrollers and FPGAs without external trimming. The MAX728CCK achieves this using an internal precision bandgap reference and trimmed feedback path.
Can the MAX728CCK be synchronized to an external clock, and what is the supported frequency range?
Yes, the MAX728CCK can be synchronized to an external TTL-compatible clock applied to the VC pin. The supported range is 115kHz to 170kHz. This capability allows noise-sensitive systems to align switching edges and avoid beat frequencies when multiple regulators operate on the same board. The MAX728CCK does not support synchronization outside this band, and no external pull-up or level-shifting is required for TTL input compatibility.
Is the MAX728CCK pin-compatible with the MAX727CCK or MAX729CCK?
Yes, the MAX728CCK is pin-compatible with the MAX727CCK and MAX729CCK - all share identical 5-pin TO-220 packaging, pinout, and electrical interface. The only functional difference is the fixed output voltage: 5V for MAX727CCK, 3.3V for MAX728CCK, and 3V for MAX729CCK. This allows board-level voltage scaling without layout changes, provided thermal and inductor sizing accommodate the respective output current and duty cycle.
What is the maximum allowable input voltage for the MAX728CCK, and what happens beyond that limit?
The absolute maximum input voltage for the MAX728CCK is 45V. Operation above 40V is outside the specified functional range and may cause premature degradation or failure. The internal bipolar switch is rated for 50V collector-to-input voltage, but exceeding 45V violates Absolute Maximum Ratings and risks permanent damage. The MAX728CCK includes no overvoltage protection - external clamping or filtering is required for systems with input transients above 45V.
Why does the MAX728CCK reduce switching frequency when the SENSE pin voltage falls below 2.0V?
The MAX728CCK reduces switching frequency when VSENSE drops below 2.0V to prevent extremely short switch-on times (<1µs), which could cause instability or inadequate current sensing. This behavior is documented in Note 5 of the datasheet and applies specifically to the MAX728 variant. It ensures reliable current limiting and regulation during startup, overload, or output short conditions - a safeguard not dependent on external components. The MAX728CCK implements this internally via oscillator scaling logic tied to the SENSE pin.
MAX728CCK Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Series:
- -
- Package/Case:
- TO-220-5
- Packaging:
- Bulk
- Product Status:
- Active
- Function:
- Step-Down
- Output Configuration:
- Positive
- Topology:
- Buck
- Output Type:
- Fixed
- Number of Outputs:
- 1
- Voltage - Input (Min):
- 8V
- Voltage - Input (Max):
- 40V
- Voltage - Output (Min/Fixed):
- 3.3V
- Voltage - Output (Max):
- -
- Current - Output:
- 2A
- Frequency - Switching:
- 100kHz
- Synchronous Rectifier:
- Yes
- Operating Temperature:
- 0°C ~ 70°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Through Hole
- Supplier Device Package:
- TO-220-5
MAX728CCK FAQ
1.How can I place an order for MAX728CCK through Aetrix?
Please submit a Request for Quotation (RFQ) for MAX728CCK 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 MAX728CCK reliable?
The price and inventory of MAX728CCK are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MAX728CCK is usually 5 days.
3.What payment methods are accepted for MAX728CCK?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MAX728CCK transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for MAX728CCK?
MAX728CCK orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your MAX728CCK 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 MAX728CCK?
For technical support, including MAX728CCK datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MAX728CCK requirements.
6.How does Aetrix verify that MAX728CCK is sourced from the original manufacturer or authorized distributors?
All MAX728CCK 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 MAX728CCK meets industry standards.
7.What is the process for return or replacement of MAX728CCK?
All MAX728CCK units undergo pre-shipment inspection (PSI). If there is an issue with MAX728CCK, 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 MAX728CCK part is unused and in its original packaging.
Return procedure for MAX728CCK:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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