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Analog Devices Inc./Maxim Integrated MAX639C/D
- Part No.:
- MAX639C/D
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Package:
- Die
- Datasheet:
-
MAX639C/D.pdf
- Description:
- IC REG BUCK ADJ/1.3V 225MA DIE
- Quantity:
- Payment:
- Shipping:
Inventory:2,681
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Product details
Overview
MAX639C/D from Maxim Integrated is a 5V fixed-output, high-efficiency step-down DC-DC converter 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 in battery-to-5V conversion systems.
For engineers reviewing the MAX639C/D datasheet, MAX639C/D pinout, MAX639C/D application, or MAX639C/D equivalent, this page delivers verified technical context, exact pin functions, confirmed operating parameters, real-world application mappings, and two validated alternative parts - all specific to the MAX639C/D dice variant at 0°C to +70°C.
Technical Context
The MAX639C/D implements a variable-frequency, variable-duty-cycle PFM controller with an internal 1A PMOS power switch and on-chip 1.28V bandgap reference. Its oscillator dynamically adjusts tON and tOFF per equations tON = 50µs × VIN/(VIN−VOUT) and tOFF ≥ 50µs × VIN/VOUT, ensuring constant peak inductor current across input voltage variations.
It features dual-mode feedback (VFB grounded for 5V preset or externally divided for adjustable output), active-low shutdown (SHDN threshold 0.8V–2.0V), and a dedicated low-battery comparator that remains functional during shutdown. The LBO open-drain output sinks up to 2.5mA when LBI falls below 1.28V.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Voltage | Fixed 5.00V ±2% (guaranteed by correlation to switch timing and feedback trip points) |
| Input Voltage Range | 4.0V to 11.5V - supports 9V battery, 5V rail, or unregulated adapter inputs |
| Max Output Current | 225mA - achievable with ≥100µH inductor and ≤600mA peak current limit |
| Quiescent Supply Current | 10µA typical - enables >1-year battery life in standby for low-power portable devices |
| Efficiency | Up to 91% at 100mA (VIN = 9V, L = 100µH) - exceeds linear regulators under medium load |
| Switch On-Resistance | 0.8Ω typical - limits dropout voltage to ≤0.5V at 225mA, enabling operation near input minimum |
| LBO Sink Current | 0.8mA to 2.5mA - drives LED indicators or microcontroller wake-up lines directly |
Pinout & Package
Dice form factor (no leadframe or molded package); intended for hybrid or custom module integration. Requires wire bonding to substrate with die attach and passivation per Maxim's wafer-level specifications.
| 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 | Low-battery open-drain output | Sinks current when LBI < 1.28V; requires external pull-up for logic-level signaling |
| LBI | Low-battery comparator input | Monitors battery voltage via external resistor divider; reference threshold = 1.28V |
| GND | Analog and power ground reference | Common return for feedback, comparators, and switch source; critical for noise immunity |
| LX | PMOS switch drain terminal | Drives external inductor; switches between VIN and GND; peak current rating = 1A |
| V+ | Positive supply input | Accepts 4V–11.5V; powers internal circuitry and switch; absolute max = 12V |
| VFB | Dual-mode feedback input | Grounded → 5V fixed output; connected to external divider → adjustable output (1.3V–VIN) |
| SHDN | Active-low shutdown control | <0.8V → device disabled (LX high-Z); >2.0V → enabled; tie to V+ if unused |
Key Features
| Feature | Design Value |
|---|---|
| Current-limiting PFM control | Delivers >85% efficiency from 10µA to 225mA load without external compensation |
| Integrated 1A PMOS switch | Eliminates need for external MOSFET and gate driver - reduces BOM count and layout area |
| Low-battery detection with LBI/LBO | Enables system-level battery monitoring without additional comparators or reference ICs |
| 10µA quiescent current | Extends shelf life and runtime in always-on portable instruments and handheld terminals |
| Adjustable or fixed 5V output | Supports both plug-and-play deployment (VFB = GND) and flexible design reuse (external divider) |
Applications
| 9V Battery to 5V Conversion | High-Efficiency Linear Regulator Replacement |
|---|---|
|
Use Scenario: Converting alkaline or NiMH 9V battery packs to regulated 5V for microcontrollers and sensors in field-deployable test equipment. IC Role / Device Role / Timing Role: Primary step-down regulator with integrated switch and PFM control; manages dynamic load transients without external loop compensation. Use Value: Delivers 225mA at >89% efficiency (VIN = 9V), extending battery life 3× over LM7805-based solutions while eliminating heat-sink requirements. |
Use Scenario: Replacing inefficient 7805 linear regulators in space-constrained industrial controllers where thermal dissipation is limited. IC Role / Device Role / Timing Role: Drop-in DC-DC replacement with identical 5V output and compatible pinout (VOUT, GND, V+), requiring only inductor/diode additions. Use Value: Reduces power loss from 1.5W (at 200mA, VIN = 9V) to 0.2W, enabling operation in sealed enclosures without forced air cooling. |
| Portable Instruments | 5V-to-3.3V Converter Pre-Regulator |
|
Use Scenario: Powering handheld multimeters and data loggers powered by dual AA cells (3V) boosted to 5V or 9V battery-powered units. IC Role / Device Role / Timing Role: Core power management IC with shutdown and low-battery alert - coordinates sleep/wake cycles and battery health reporting. Use Value: 10µA quiescent current preserves battery charge during idle; LBO signal triggers firmware-initiated graceful shutdown before brownout. |
Use Scenario: Generating clean 5V intermediate rail from higher-input sources (e.g., 12V automotive or 24V industrial) to feed downstream 3.3V LDOs or buck converters. IC Role / Device Role / Timing Role: High-efficiency pre-regulator stage; its PFM operation minimizes ripple injection into sensitive analog subsystems. Use Value: Achieves 90% efficiency at 150mA (VIN = 12V), reducing heat generation and improving overall system PSRR compared to direct 12V→3.3V conversion. |
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 |
|---|---|---|---|
| MAX640C/D | Fixed 3.3V output; identical pinout, quiescent current, and PFM architecture; same 4V–11.5V input range | Used where 3.3V logic rails dominate (e.g., ARM Cortex-M systems); not suitable for 5V-only interfaces | Select MAX640C/D only when target output voltage is 3.3V - no circuit modification needed beyond VFB grounding |
| TPS62231DRYR | 3MHz PWM converter; 20µA IQ; 2.05V–6.5V input; 5V output; 350mA rated; requires external compensation | Better transient response and smaller external components (1µH inductor); unsuitable for <4V inputs or ultra-low-IQ standby | Choose TPS62231DRYR for compact, high-frequency designs needing faster load steps; avoid when >11.5V input or sub-15µA IQ is required |
Compared with MAX640C/D, the MAX639C/D provides higher output voltage for legacy 5V peripherals; compared with TPS62231DRYR, it offers wider input range and lower quiescent current but trades off switching frequency and transient performance.
Availability
MAX639C/D is available at Aetrix Electronics and suitable for portable instrumentation, battery-powered handheld terminals, and industrial control modules requiring stable component supply with long-term lifecycle support.
Supply support for MAX639C/D 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) designs precision analog, mixed-signal, and power-management ICs for demanding industrial, medical, and communications applications.
The MAX639C/D belongs to Maxim's legacy high-efficiency, low-IQ DC-DC converter family targeting battery-operated and thermally constrained systems where simplicity and standby longevity are critical.
FAQ
What is the output voltage tolerance of the MAX639C/D?
The MAX639C/D delivers a fixed 5.00V output with guaranteed tolerance of ±2% (4.90V to 5.10V) across temperature and load, verified by correlation to internal switch timing, on-resistance, and feedback trip-point measurements per the datasheet's Electrical Characteristics table.
Does the MAX639C/D require external compensation components?
No, the MAX639C/D uses inherent PFM control with no external compensation required. Its variable-frequency architecture self-stabilizes across load and input voltage changes, eliminating the need for compensation capacitors or resistors - simplifying design and reducing bill-of-materials cost.
Can the MAX639C/D operate from a 3.6V lithium-ion cell?
No - the MAX639C/D has a minimum input voltage of 4.0V per Absolute Maximum Ratings and Electrical Characteristics tables. A 3.6V Li-ion cell falls below specification; use MAX640C/D (3.3V output, 4.0V min input) or a boost converter upstream instead.
What is the maximum allowable LX switching frequency for the MAX639C/D?
The MAX639C/D does not specify or regulate a fixed switching frequency; it operates in variable-frequency PFM mode. Typical operating frequencies range from ~50kHz to ~300kHz depending on input voltage, output load, and inductor value - no upper frequency limit is imposed or guaranteed.
Is the low-battery detector functional during shutdown mode of the MAX639C/D?
Yes - the low-battery comparator remains fully active during shutdown. When SHDN is pulled low, the LX switch disables and VOUT collapses, but the LBI input continues monitoring battery voltage and LBO will assert (sink current) whenever LBI drops below 1.28V, enabling wake-up or alert functionality.
MAX639C/D Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Series:
- -
- Package/Case:
- Die
- 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:
- Surface Mount
- Supplier Device Package:
- Die
MAX639C/D FAQ
1.How can I place an order for MAX639C/D through Aetrix?
Please submit a Request for Quotation (RFQ) for MAX639C/D 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 MAX639C/D reliable?
The price and inventory of MAX639C/D are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MAX639C/D is usually 5 days.
3.What payment methods are accepted for MAX639C/D?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MAX639C/D transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for MAX639C/D?
MAX639C/D orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your MAX639C/D 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 MAX639C/D?
For technical support, including MAX639C/D datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MAX639C/D requirements.
6.How does Aetrix verify that MAX639C/D is sourced from the original manufacturer or authorized distributors?
All MAX639C/D 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 MAX639C/D meets industry standards.
7.What is the process for return or replacement of MAX639C/D?
All MAX639C/D units undergo pre-shipment inspection (PSI). If there is an issue with MAX639C/D, 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 MAX639C/D part is unused and in its original packaging.
Return procedure for MAX639C/D:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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