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Analog Devices Inc./Maxim Integrated MAX640CPA+
- Part No.:
- MAX640CPA+
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Package:
- 8-DIP (0.300", 7.62mm)
- Datasheet:
-
MAX640CPA+.pdf
- Description:
- IC REG BUCK ADJ/1.3V 225MA 8PDIP
- Quantity:
- Payment:
- Shipping:
Inventory:1,165
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Product details
Overview
MAX640CPA+ from Maxim Integrated is a 3.3V fixed-output, high-efficiency step-down DC-DC converter with PFM control, delivering up to 225mA output current, 10µA quiescent current, and operating from 4V to 11.5V input. It integrates a 1A PMOS power switch and features low-battery detection (LBI/LBO) for portable 9V-to-3.3V conversion in battery-powered instrumentation.
For engineers reviewing the MAX640CPA+ datasheet, MAX640CPA+ pinout, MAX640CPA+ application, or MAX640CPA+ equivalent, key selection criteria include its 3.3V preset output, 8-pin plastic DIP package, PFM efficiency across light-to-heavy loads, and integrated low-battery comparator functionality.
Technical Context
The MAX640CPA+ employs a current-limiting pulse-frequency-modulated (PFM) control scheme that dynamically adjusts switching frequency and duty cycle to maintain constant peak inductor current (IPEAK = 50µs × VIN/L), enabling high efficiency from 10µA to 225mA load range without external compensation.
It integrates an internal 1.28V bandgap reference, dual-mode feedback (VFB grounded for 3.3V fixed output or externally divided for adjustable operation), and a dedicated low-battery detector with independent LBI input and open-drain LBO output - all active during shutdown mode.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Voltage | Fixed 3.3V ±3% (guaranteed over temperature and line/load) |
| Input Voltage Range | 4.0V to 11.5V - supports 9V batteries, 5V rails, and industrial supplies |
| Max Output Current | 225mA - sufficient for microcontrollers, sensors, and RF modules |
| Quiescent Current | 10µA - enables multi-year battery life in always-on portable devices |
| Efficiency | Up to 89% at 100mA (VIN = 5V, L = 100µH) - exceeds linear regulators under medium load |
| Low-Battery Threshold | 1.28V on LBI pin - configurable detection voltage via external resistor divider |
| Shutdown Threshold | SHDN < 0.8V disables switching; >2.0V enables regulation - compatible with logic-level control |
Pinout & Package
MAX640CPA+ is housed in an 8-pin plastic DIP (dual in-line package) with 0.300" wide body, through-hole mounting, and industry-standard pin spacing (0.100" pitch). Pin 1 is marked by a notch or dot.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VOUT (Pin 1) | Regulated output sense node | Internally connected to feedback divider; must be tied directly to output capacitor for stable regulation |
| LBO (Pin 2) | Open-drain low-battery output | Sinks up to 10mA when LBI falls below 1.28V; requires external pull-up for logic-level signaling |
| LBI (Pin 3) | Low-battery input | Monitors external voltage divider; comparator remains active in shutdown mode |
| GND (Pin 4) | Power and signal ground reference | Must be connected to star ground point near input/output capacitors to minimize ground bounce |
| LX (Pin 5) | PMOS switch drain terminal | Drives external inductor; peak current limited to 600mA; requires Schottky catch diode |
| V+ (Pin 6) | Positive supply input | Accepts 4–11.5V; absolute max 12V; bypass with ≥33µF low-ESR capacitor |
| VFB (Pin 7) | Dual-mode feedback input | Grounded for 3.3V fixed output; connected to resistor divider for adjustable outputs (1.3V–VIN) |
| SHDN (Pin 8) | Active-low shutdown control | Pulling below 0.8V disables LX switching and reduces supply current to <1µA |
Key Features
| Feature | Design Value |
|---|---|
| PFM control architecture | Enables 10µA quiescent current and >85% efficiency at 10µA–100mA loads - ideal for intermittent-sensing applications |
| Integrated 1A PMOS switch | Eliminates need for external MOSFET and gate driver - reduces BOM count and PCB area in space-constrained designs |
| Low-battery detection circuit | Dedicated LBI/LBO pins with 1.28V internal reference - enables system-level battery monitoring without additional ICs |
| Fixed 3.3V output option | VFB grounded configuration requires zero external resistors - simplifies design and improves production yield |
| Startup time | Typically <10ms to 3.3V (VIN = 5V, ILOAD = 100mA, L = 100µH) - suitable for fast-wake microcontroller systems |
Applications
| Handheld Test Equipment | Industrial Sensor Nodes |
|---|---|
|
Use Scenario: Portable multimeter powered by two 9V alkaline batteries requiring stable 3.3V for MCU and ADC. IC Role / Device Role / Timing Role: Primary 3.3V power supply with integrated low-battery warning to alert user before battery depletion. Use Value: 10µA quiescent current extends battery life beyond 2 years in sleep mode; PFM maintains >80% efficiency at 100µA sensor bias current. |
Use Scenario: Wireless temperature sensor node in factory automation using AA batteries and LoRaWAN radio. IC Role / Device Role / Timing Role: Efficient 3.3V rail generator for ultra-low-power MCU, analog front-end, and RF transceiver. Use Value: Delivers 225mA peak current for radio transmit bursts while maintaining <15mV output ripple with 100µF/0.1µF output filter. |
| Medical Point-of-Care Devices | Legacy Industrial Controllers |
|
Use Scenario: Battery-backed glucose meter with LCD display and USB charging interface. IC Role / Device Role / Timing Role: Main 3.3V regulator with LBO-driven LED indicator for end-of-life battery alert. Use Value: Fixed 3.3V output eliminates feedback resistor tolerance errors; shutdown mode draws <1µA during USB charging standby. |
Use Scenario: Retrofit power solution for aging PLC I/O modules needing 3.3V logic from existing 9V or 12V backplane rails. IC Role / Device Role / Timing Role: Drop-in replacement for inefficient 78L33 linear regulators to reduce thermal stress and improve reliability. Use Value: Replaces linear regulator with 89% efficiency at 100mA - cuts power dissipation from 670mW to <100mW in same footprint. |
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 |
|---|---|---|---|
| MAX640CSA+ | Same electrical specs, but in 8-pin SO package (surface-mount); no through-hole mounting capability | Better suited for automated SMT assembly and higher-density PCBs; not interchangeable in DIP footprints | Select MAX640CSA+ only if board layout supports SOIC-8 and reflow soldering is available. |
| TPS62231DRYR | 3.3V fixed, 300mA output, 2.5V–6.5V input, 17µA IQ, 2.5MHz PWM - higher frequency, lower IQ than MAX640CPA+, but narrower input range | Requires external compensation; lacks integrated low-battery detector; optimized for compact Li-ion-powered devices | Choose TPS62231DRYR when board space is critical and input voltage is constrained to ≤6.5V; retain MAX640CPA+ for 4–11.5V flexibility and LBI/LBO integration. |
Compared with MAX640CSA+, the MAX640CPA+ offers identical regulation performance in a through-hole package for prototyping and legacy repair; compared with TPS62231DRYR, it trades higher switching frequency for wider input range and built-in battery monitoring - making it superior for 9V battery and industrial supply applications.
Availability
MAX640CPA+ is available at Aetrix Electronics and suitable for handheld test equipment, industrial sensor nodes, medical point-of-care devices, and legacy industrial controllers requiring stable component supply with long-term availability assurance.
Supply support for MAX640CPA+ 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 and mixed-signal ICs for power management, sensing, and communication.
The MAX639/MAX640/MAX653 family was designed specifically for low-quiescent-current, high-efficiency step-down conversion in portable and battery-critical applications - emphasizing simplicity, minimal external components, and integrated system monitoring.
FAQ
What is the guaranteed output voltage tolerance for MAX640CPA+?
The MAX640CPA+ guarantees a 3.3V output within ±3% (3.17V to 3.43V) over full temperature range (0°C to +70°C), input voltage (4V to 11.5V), and load (0mA to 100mA), as specified in the Electrical Characteristics table under "Output Voltage" for MAX640.
Can MAX640CPA+ operate from a single 3.7V Li-ion cell?
No - the MAX640CPA+ requires a minimum input voltage of 4.0V per Absolute Maximum Ratings and Electrical Characteristics tables. A single Li-ion cell (nominal 3.7V, discharged to ~3.0V) falls below this threshold and cannot power the MAX640CPA+ reliably.
Does MAX640CPA+ require external feedback resistors for 3.3V operation?
No - the MAX640CPA+ provides a fixed 3.3V output when the VFB pin (Pin 7) is connected directly to GND. No external resistors are needed, simplifying design and eliminating resistor tolerance errors in the feedback path.
What is the maximum allowable inductor value for MAX640CPA+?
The MAX640CPA+ datasheet does not specify a maximum inductor value, but recommends ≥100µH for optimal performance. Larger values (e.g., 470µH) improve light-load efficiency and reduce ripple, as confirmed by Typical Operating Characteristics graphs showing higher efficiency at 470µH vs. 100µH under 25mA load.
Is the low-battery detector functional during shutdown mode?
Yes - the low-battery comparator remains fully active during shutdown mode. When SHDN is pulled low, the LX switch disables and VOUT drops, but the LBI input continues monitoring voltage and LBO will assert if LBI falls below 1.28V, enabling battery monitoring even when the main regulator is off.
MAX640CPA+ Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Series:
- -
- Package/Case:
- 8-DIP (0.300", 7.62mm)
- Packaging:
- Tube
- Product Status:
- Obsolete
- 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:
- 0°C ~ 70°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Through Hole
- Supplier Device Package:
- 8-PDIP
MAX640CPA+ FAQ
1.How can I place an order for MAX640CPA+ through Aetrix?
Please submit a Request for Quotation (RFQ) for MAX640CPA+ 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 MAX640CPA+ reliable?
The price and inventory of MAX640CPA+ are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MAX640CPA+ is usually 5 days.
3.What payment methods are accepted for MAX640CPA+?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MAX640CPA+ transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for MAX640CPA+?
MAX640CPA+ orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your MAX640CPA+ 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 MAX640CPA+?
For technical support, including MAX640CPA+ datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MAX640CPA+ requirements.
6.How does Aetrix verify that MAX640CPA+ is sourced from the original manufacturer or authorized distributors?
All MAX640CPA+ 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 MAX640CPA+ meets industry standards.
7.What is the process for return or replacement of MAX640CPA+?
All MAX640CPA+ units undergo pre-shipment inspection (PSI). If there is an issue with MAX640CPA+, 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 MAX640CPA+ part is unused and in its original packaging.
Return procedure for MAX640CPA+:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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