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Analog Devices Inc./Maxim Integrated MAX640EPA
- Part No.:
- MAX640EPA
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Package:
- 8-DIP (0.300", 7.62mm)
- Datasheet:
-
MAX640EPA.pdf
- Description:
- IC REG BUCK ADJ/1.3V 225MA 8PDIP
- Quantity:
- Payment:
- Shipping:
Inventory:2,484
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Product details
Overview
MAX640EPA from Maxim Integrated is a 3.3V fixed-output, step-down DC-DC switching regulator with internal 1A PMOS switch, 10µA quiescent current, and 225mA output capability over 4V–11.5V input range. It employs current-limiting pulse-frequency-modulated (PFM) control for high efficiency across light-to-heavy loads and integrates low-battery detection (LBI/LBO) for portable power management in battery-powered instrumentation.
For engineers reviewing the MAX640EPA datasheet, MAX640EPA pinout, MAX640EPA application, or MAX640EPA equivalent, key selection criteria include its -40°C to +85°C temperature rating in 8-pin plastic DIP, preset 3.3V output accuracy (±4% over full temperature/load), PFM efficiency advantage at light loads, and compatibility with standard 100µH inductors and Schottky diodes like 1N5817.
Technical Context
The MAX640EPA implements a variable-frequency, variable-duty-cycle PFM control scheme that dynamically adjusts tON and tOFF per Equations (1) and (2) to maintain constant peak inductor current-ensuring stable regulation without external compensation. Its error comparator drives an on-demand oscillator only when output voltage dips below regulation, minimizing idle power loss.
It features dual-mode feedback via VFB: grounding VFB selects the factory-trimmed 3.3V output (typical tolerance ±4%), while connecting VFB to an external resistor divider enables adjustable operation down to 1.3V. The integrated low-battery detector compares LBI to a 1.28V bandgap reference and asserts open-drain LBO independently of shutdown state.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Voltage | Fixed 3.3V ±4% over full temperature and load range-guaranteed by correlation to switch timing and feedback threshold parameters. |
| Input Voltage Range | 4.0V to 11.5V-supports 9V battery, 5V rail, or wide-input industrial supplies without external pre-regulation. |
| Max Output Current | 225mA with 100µH inductor-enables compact, low-component-count power conversion for medium-power portable loads. |
| Quiescent Supply Current | 10µA typical at no load-delivers >85% efficiency at 1mA load, critical for battery runtime extension. |
| Switch Type | Internal 1A PMOS power switch-eliminates need for external MOSFET and gate driver, reducing BOM count and layout complexity. |
| Low-Battery Detection | 1.28V LBI threshold with 25µs LBO delay-provides reliable end-of-life signaling for 3.3V systems using simple resistor dividers. |
| Efficiency | Up to 91% at 100mA (VIN = 6V, L = 100µH)-exceeds linear regulators in thermal performance and extends battery life significantly. |
Pinout & Package
MAX640EPA is housed in an 8-pin plastic DIP package (0.300" width), rated for -40°C to +85°C operation, with through-hole mounting and industry-standard SOIC-compatible footprint.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VOUT | Regulated output sense node | Internally connected to voltage divider; must be tied directly to output capacitor for stable regulation. |
| LBO | Open-drain low-battery output | Sinks up to 10mA when LBI < 1.28V; requires external pull-up for logic-level interface to microcontroller. |
| LBI | Low-battery input comparator | Monitors battery voltage via resistor divider; remains active during SHDN for system-level power monitoring. |
| GND | Power and signal reference ground | Must be star-connected with CIN, COUT, and diode anode to minimize ground bounce-induced ripple. |
| LX | PMOS switch drain terminal | Drives external inductor; peak current limited to 600mA-requires ≥100µH inductor to prevent saturation. |
| V+ | Positive supply input | Accepts 4V–11.5V; absolute max 12V-must be decoupled with ≥33µF low-ESR capacitor near pin. |
| VFB | Dual-mode feedback input | Grounded for 3.3V fixed output; connected to resistor divider for adjustable outputs ≥1.3V. |
| SHDN | Active-low shutdown control | Pulled below 0.8V disables LX; pulled above 2V enables regulation-tie to V+ if unused. |
Key Features
| Feature | Design Value |
|---|---|
| Current-limiting PFM control | Delivers >85% efficiency at 1mA load and maintains regulation down to zero load without burst-mode noise. |
| Integrated 1A PMOS switch | Reduces external component count to just inductor, diode, and two capacitors-ideal for space-constrained PCBs. |
| Low-battery detection with LBO | Enables autonomous battery monitoring without MCU intervention-critical for handheld instruments and data loggers. |
| 10µA quiescent current | Extends shelf life and runtime in always-on battery applications such as remote sensors and medical wearables. |
| Fixed 3.3V output with ±4% tolerance | Meets industrial and portable equipment requirements without trimming resistors or calibration overhead. |
Applications
| 9V Battery to 3.3V Conversion | High-Efficiency Linear Regulator Replacement |
|---|---|
Use Scenario: Powering 3.3V microcontrollers and sensors from a single 9V alkaline battery in portable test equipment. IC Role / Device Role / Timing Role: Primary DC-DC step-down regulator delivering regulated 3.3V with PFM-controlled switching frequency. Use Value: Achieves 89% efficiency at 100mA (vs. ~40% for 78L33), extending battery life by >2× and eliminating thermal derating concerns. | Use Scenario: Replacing LM1117-3.3 in embedded controllers where input voltage exceeds 5.5V and heat dissipation is constrained. IC Role / Device Role / Timing Role: Efficient buck converter replacing linear dropout regulator in fixed-voltage power domains. Use Value: Reduces power dissipation from 350mW (linear) to <50mW (switching) at 100mA, enabling fanless enclosure design. |
| Portable Instruments and Handy-Terminals | 5V-to-3.3V Converters |
Use Scenario: Supplying 3.3V logic rails in handheld multimeters and barcode scanners powered by AA/AAA cells. IC Role / Device Role / Timing Role: Core power management IC with integrated low-battery warning for user interface feedback. Use Value: LBI/LBO circuitry provides accurate end-of-life detection at 3.3V system level, improving field reliability and user experience. | Use Scenario: Generating clean 3.3V from existing 5V system rails in industrial I/O modules and communication interfaces. IC Role / Device Role / Timing Role: Secondary point-of-load regulator converting 5V backplane voltage to 3.3V logic supply. Use Value: Delivers 225mA at 3.3V with <10mV ripple (100µH + 100µF), meeting tight noise budgets for ADCs and RF front-ends. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar step-down DC-DC converter applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| TPS62231DRYR | 3.3V fixed, 300mA output, 2.05V–6.5V input, 17µA IQ, 2.5MHz PWM mode | Higher switching frequency enables smaller inductors/caps but lacks low-battery detection | Preferred for space-constrained designs needing higher output current and tighter output tolerance (±1.5%) |
| LT1931ES5#TRMPBF | 3.3V fixed, 1.3A switch, 2.6V–16V input, 100µA IQ, PWM/PFM hybrid control | Higher input range and current drive, but larger SO-5 package and no LBI/LBO pins | Chosen when input voltage may exceed 11.5V or output load exceeds 225mA, accepting higher quiescent current |
Compared with TPS62231DRYR and LT1931ES5#TRMPBF, the MAX640EPA uniquely combines ultra-low 10µA quiescent current, integrated low-battery detection, and DIP packaging for legacy prototyping-making it optimal for cost-sensitive, battery-critical, or through-hole production environments.
Availability
MAX640EPA is available at Aetrix Electronics and suitable for portable instrumentation, battery-powered handheld terminals, and industrial 3.3V point-of-load conversion requiring stable component supply and long-term obsolescence support.
Supply support for MAX640EPA 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 U.S.-based semiconductor company specializing in high-performance analog, mixed-signal, and power management ICs for industrial, automotive, and communications markets.
The MAX639/MAX640/MAX653 family was designed specifically for low-quiescent-current, high-efficiency step-down conversion in portable and battery-operated systems-emphasizing simplicity, reliability, and minimal external component count.
FAQ
What is the guaranteed output voltage tolerance for MAX640EPA across temperature and load?
The MAX640EPA guarantees a 3.3V output with ±4% tolerance over the full operating temperature range (-40°C to +85°C) and load range (0–225mA). This specification is confirmed by correlation to measured switch on-resistance, on/off times, and feedback threshold parameters-not just initial room-temperature testing.
Can MAX640EPA operate from a 3.6V lithium-ion battery?
No-MAX640EPA requires a minimum input voltage of 4.0V per Absolute Maximum Ratings and Electrical Characteristics tables. A 3.6V Li-ion cell falls below this threshold, especially under load or at end-of-discharge. For 3.6V inputs, consider the MAX640ESA's sibling MAX653EPA (3.0V output, 3.5V min input) or a dedicated low-VIN buck converter.
Does MAX640EPA require external compensation components?
No-MAX640EPA uses an internally compensated, on-demand PFM oscillator architecture. No external compensation network is needed. Stability is ensured across all valid input voltages and output loads when using recommended 100µH inductors and standard electrolytic or low-ESR capacitors.
How does the low-battery detection function behave during shutdown mode?
The low-battery comparator remains fully active during shutdown mode: LBI continues monitoring input voltage, and LBO will assert (pull low) whenever LBI drops below 1.28V-even with SHDN held low. This allows continuous battery health monitoring without waking the main regulator.
What is the maximum allowable inductor value for MAX640EPA, and why?
While the datasheet specifies a minimum of 100µH, there is no strict upper limit-but inductance values beyond 470µH reduce efficiency at medium-to-heavy loads due to increased core losses and slower transient response. Typical designs use 100µH (for 225mA max) or 470µH (for lower ripple and better light-load efficiency), both validated in the MAX640EPA's Typical Operating Characteristics graphs.
MAX640EPA Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Series:
- -
- Package/Case:
- 8-DIP (0.300", 7.62mm)
- Packaging:
- Bulk
- Product Status:
- Active
- Function:
- Step-Down
- Output Configuration:
- Positive
- Topology:
- Buck
- Output Type:
- Adjustable (Fixed)
- Number of Outputs:
- 1
- Voltage - Input (Min):
- 4V
- Voltage - Input (Max):
- 11.5V
- Voltage - Output (Min/Fixed):
- 1.3V (3.3V)
- Voltage - Output (Max):
- 11.5V
- Current - Output:
- 225mA
- Frequency - Switching:
- -
- Synchronous Rectifier:
- No
- Operating Temperature:
- -40°C ~ 85°C
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Through Hole
- Supplier Device Package:
- 8-PDIP
MAX640EPA FAQ
1.How can I place an order for MAX640EPA through Aetrix?
Please submit a Request for Quotation (RFQ) for MAX640EPA 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 MAX640EPA reliable?
The price and inventory of MAX640EPA are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MAX640EPA is usually 5 days.
3.What payment methods are accepted for MAX640EPA?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MAX640EPA transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for MAX640EPA?
MAX640EPA orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your MAX640EPA 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 MAX640EPA?
For technical support, including MAX640EPA datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MAX640EPA requirements.
6.How does Aetrix verify that MAX640EPA is sourced from the original manufacturer or authorized distributors?
All MAX640EPA 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 MAX640EPA meets industry standards.
7.What is the process for return or replacement of MAX640EPA?
All MAX640EPA units undergo pre-shipment inspection (PSI). If there is an issue with MAX640EPA, 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 MAX640EPA part is unused and in its original packaging.
Return procedure for MAX640EPA:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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