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Analog Devices Inc./Maxim Integrated MAX639CPA+
- Part No.:
- MAX639CPA+
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Package:
- 8-DIP (0.300", 7.62mm)
- Datasheet:
-
MAX639CPA+.pdf
- Description:
- IC REG BUCK ADJ/1.3V 225MA 8PDIP
- Quantity:
- Payment:
- Shipping:
Inventory:342
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Product details
Overview
MAX639CPA+ from Maxim Integrated is a 5V fixed-output, high-efficiency step-down DC-DC switching regulator with internal 1A PMOS switch, 10µA quiescent current, 4V–11.5V input range, and up to 225mA output current. It employs current-limiting pulse-frequency-modulated (PFM) control for wide-load efficiency and integrates low-battery detection (LBI/LBO) for portable power management.
For engineers reviewing the MAX639CPA+ datasheet, MAX639CPA+ pinout, MAX639CPA+ application, or MAX639CPA+ equivalent, key selection criteria include its 5V preset output, 8-pin plastic DIP package, PFM efficiency profile across microamp-to-mA loads, and compatibility with standard 100µH inductors and Schottky diodes in battery-powered systems.
Technical Context
The MAX639CPA+ implements a variable-frequency, variable-duty-cycle PFM controller that dynamically adjusts tON and tOFF per Equations (1) and (2) to maintain constant peak inductor current (IPEAK = 50µs·V / L). Its error comparator drives an on-demand oscillator only when output voltage droops, minimizing no-load supply current.
It features dual-mode feedback via VFB: grounding VFB selects internal 5V regulation (MAX639), while external resistor dividers enable adjustable outputs from 1.3V to VIN. The low-battery detector operates independently of shutdown mode using a precise 1.28V internal reference and open-drain LBO output.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Voltage | Fixed 5.00V ±2% (guaranteed over temperature and load) |
| Input Voltage Range | 4.0V to 11.5V - supports 9V battery, dual-AA (via inverter config), or industrial 5–12V rails |
| Max Output Current | 225mA at VIN ≥ 6V with 100µH inductor - enables compact 5V supply for microcontrollers and sensors |
| Quiescent Current | 10µA typical - sustains >1-year battery life in standby for portable instruments |
| Efficiency | 89% at 100mA, VIN = 9V - exceeds linear regulators by >40% at medium loads |
| Switch On-Resistance | 0.8Ω typical - limits dropout and thermal rise in DIP package at full load |
| LBO Threshold | 1.28V ±20mV - enables accurate low-battery warning with external resistor divider |
Pinout & Package
MAX639CPA+ uses an 8-pin plastic DIP (dual in-line package) with 0.300" body width and through-hole mounting. Pin 1 is bottom-left corner when notch faces up.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VOUT (Pin 1) | Regulated output sense node | Connected directly to output capacitor; internal voltage divider sets 5V when VFB grounded |
| LBO (Pin 2) | Low-battery open-drain output | Sinks up to 10mA when LBI < 1.28V; requires external pull-up for logic-level signaling |
| LBI (Pin 3) | Low-battery comparator input | Monitors battery voltage via external resistor divider; remains active in shutdown |
| GND (Pin 4) | Analog and power ground reference | Must be star-connected with CIN, COUT, and diode anode 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 input supply | Accepts 4–11.5V; must be bypassed with ≥33µF low-ESR capacitor near pin |
| VFB (Pin 7) | Dual-mode feedback input | Ground for 5V fixed output; connects to external divider for adjustable outputs (1.3V–VIN) |
| SHDN (Pin 8) | 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 |
|---|---|
| PFM control architecture | Delivers >85% efficiency from 10µA to 200mA load - eliminates light-load inefficiency of PWM |
| Integrated 1A PMOS switch | Reduces BOM to only inductor, diode, and two capacitors - ideal for space-constrained PCBs |
| Low-battery detection with independent operation | Enables system-level battery monitoring without disabling regulation - critical for handheld terminals |
| Adjustable or fixed 5V output | Zero-resistor configuration for 5V; flexible resistor-divider support for custom voltages (e.g., 3.3V, 2.5V) |
| Start-up time under 10ms | Reaches 5V output in ≤8ms at 100mA load and 9V input - suitable for wake-on-event applications |
Applications
| 9V Battery to 5V Conversion | High-Efficiency Linear Regulator Replacement |
|---|---|
|
Use Scenario: Powering microcontroller-based data loggers from a single 9V alkaline battery. IC Role / Device Role / Timing Role: Primary 5V DC-DC converter delivering regulated output with dynamic load response. Use Value: Extends battery life by 3× vs. 78L05 linear regulator due to 89% efficiency at 100mA. |
Use Scenario: Replacing obsolete 7805 in industrial sensor nodes requiring low heat dissipation. IC Role / Device Role / Timing Role: Drop-in switching alternative maintaining same 5V output and footprint-compatible layout. Use Value: Eliminates heatsink requirement and reduces board temperature rise by >25°C at 150mA load. |
| Portable Instruments | 5V-to-3.3V Converter Interface |
|
Use Scenario: Supplying 5V rail to LCD display and keypad controller in handheld multimeter. IC Role / Device Role / Timing Role: Main power IC with integrated low-battery alert (LBI/LBO) for user notification. Use Value: Enables "low battery" icon activation at precisely 6.8V using R1/R2 divider - improves UX reliability. |
Use Scenario: Generating clean 3.3V for SPI peripherals from existing 5V system rail. IC Role / Device Role / Timing Role: Secondary regulator configured via VFB divider to output 3.3V with tight tolerance. Use Value: Achieves ±1.5% 3.3V accuracy across -20°C to +70°C - meets RS-485 transceiver requirements. |
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 |
|---|---|---|---|
| MAX640CPA+ | Fixed 3.3V output; identical pinout, package, and PFM architecture; 10µA IQ, 225mA max | Used where 3.3V logic supply is required instead of 5V; shares same layout and external components | Select MAX640CPA+ when system requires 3.3V instead of 5V - no PCB changes needed |
| TPS62231DRVR | 3MHz PWM converter; 20µA IQ; 300mA output; 2mm × 2mm WSON package; no LBI/LBO | Targets ultra-compact designs with higher switching frequency; lacks battery monitoring capability | Choose TPS62231DRVR for space-constrained apps needing smaller inductors - but add external battery monitor |
Compared with MAX639CPA+, MAX640CPA+ offers identical form-factor and efficiency but targets 3.3V systems, while TPS62231DRVR provides higher density and frequency at the cost of missing integrated low-battery detection and requiring different layout practices.
Availability
MAX639CPA+ is available at Aetrix Electronics and suitable for portable instrumentation, battery-powered handheld terminals, and industrial sensor nodes requiring stable component supply with long lifecycle visibility.
Supply support for MAX639CPA+ 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, interface, and sensing applications.
The MAX639/MAX640/MAX653 family was designed specifically for low-power, battery-operated systems requiring high-efficiency step-down conversion with integrated power management features like low-battery detection.
FAQ
What is the maximum input voltage rating for the MAX639CPA+?
The MAX639CPA+ has an absolute maximum input voltage of 12V, with recommended operating range of 4.0V to 11.5V. Exceeding 12V may cause permanent damage. At VIN = 11.5V, the device delivers full 225mA output with 89% efficiency when paired with a 100µH inductor and proper output capacitance. Always observe derating guidelines for continuous operation.
Can the MAX639CPA+ be used in an inverting configuration to generate -5V?
Yes, the MAX639CPA+ supports inverting operation: connect VOUT to system ground and use GND as the regulated -5V output. This configuration maintains the same 4–11.5V input range and achieves ~85% efficiency at 10mA with 470µH inductor (per Figure 8). Ensure differential voltage between V+ and VOUT does not exceed 11.5V to avoid overstress.
Does the MAX639CPA+ require an external diode, and what type is recommended?
Yes, the MAX639CPA+ requires an external Schottky diode (e.g., 1N5817) connected from LX to VOUT. Fast turn-on/turn-off is essential to minimize conduction and switching losses. Signal diodes like 1N4148 are acceptable only below 100mA peak current. General-purpose rectifiers (e.g., 1N4001) must be avoided due to slow recovery causing excessive loss and instability.
How does the low-battery detection function work on the MAX639CPA+?
The MAX639CPA+ uses an internal 1.28V reference to compare LBI voltage against threshold. When LBI drops below 1.28V, LBO sinks current (open-drain) to signal low battery. LBI is typically biased via resistor divider from V+; calculation uses R1 = R2 × ((VLB / 1.28V) – 1). Critically, this comparator remains active during SHDN mode, enabling battery monitoring even when regulator is off.
What is the recommended inductor value and saturation current for MAX639CPA+ at 225mA output?
For 225mA continuous output, use a 100µH inductor rated for ≥600mA peak current (e.g., Sumida CDR105-101 or equivalent). Equation IPEAK = 50µs·V / L confirms 600mA at VIN = 9V. Inductor series resistance must be ≤0.3Ω to limit dropout and maintain efficiency; ferrite-core types (not air-core or RF chokes) are preferred for EMI robustness.
MAX639CPA+ 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 (5V)
- 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
MAX639CPA+ FAQ
1.How can I place an order for MAX639CPA+ through Aetrix?
Please submit a Request for Quotation (RFQ) for MAX639CPA+ 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 MAX639CPA+ reliable?
The price and inventory of MAX639CPA+ are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MAX639CPA+ is usually 5 days.
3.What payment methods are accepted for MAX639CPA+?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MAX639CPA+ transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for MAX639CPA+?
MAX639CPA+ orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your MAX639CPA+ 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 MAX639CPA+?
For technical support, including MAX639CPA+ datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MAX639CPA+ requirements.
6.How does Aetrix verify that MAX639CPA+ is sourced from the original manufacturer or authorized distributors?
All MAX639CPA+ 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 MAX639CPA+ meets industry standards.
7.What is the process for return or replacement of MAX639CPA+?
All MAX639CPA+ units undergo pre-shipment inspection (PSI). If there is an issue with MAX639CPA+, 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 MAX639CPA+ part is unused and in its original packaging.
Return procedure for MAX639CPA+:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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