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Analog Devices Inc./Maxim Integrated MAX639ESA+T
- Part No.:
- MAX639ESA+T
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Package:
- 8-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
MAX639ESA+T.pdf
- Description:
- IC REG BUCK ADJ/1.3V 225MA 8SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:3,533
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Product details
Overview
MAX639ESA+T 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 225mA output capability. 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 MAX639ESA+T datasheet, MAX639ESA+T pinout, MAX639ESA+T application, or MAX639ESA+T equivalent, key selection considerations include its -40°C to +85°C operating range, SO-8 package, preset 5V output, PFM efficiency profile across microamp-to-mA loads, and integrated low-battery comparator functionality.
Technical Context
The MAX639ESA+T uses a variable-frequency, variable-duty-cycle PFM control scheme that modulates both on-time (tON = 50µs × VIN/(VIN − VOUT)) and off-time (tOFF ≥ 50µs × VIN/VOUT) to maintain constant peak inductor current. Its error comparator drives a 15µs-startup oscillator only when output voltage droops, minimizing no-load supply current.
It integrates a dual-mode feedback pin (VFB): grounding VFB selects internal 5V regulation (MAX639), while external resistor dividers enable adjustable outputs from 1.3V to VIN. The 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 5.00V ±2% (guaranteed by correlation to switch timing and feedback threshold) |
| Input Voltage Range | 4.0V to 11.5V - supports 9V battery, 5V rail, or industrial 5–12V supplies |
| Max Output Current | 225mA at VIN ≥ 6V with 100µH inductor - limited by 600mA peak inductor current |
| Quiescent Supply Current | 10µA typical (SHDN = VIN, no load) - enables multi-year battery life in standby |
| Efficiency | 89% typical at 100mA, VIN = 9V, L = 100µH - exceeds linear regulators above ~50mA load |
| Operating Temperature | -40°C to +85°C - qualified for industrial and extended-temperature embedded applications |
| Shutdown Threshold | 0.80V to 1.15V (SHDN low) - ensures reliable disable below logic-low level |
Pinout & Package
MAX639ESA+T is housed in an 8-pin SO (Small Outline) package per JEDEC MS-012, 150-mil body width, with exposed pad not electrically connected. Pin 1 is marked by notch or dot; pin numbering is counterclockwise from top-left corner.
| 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) | 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 during shutdown |
| GND (Pin 4) | Power and signal reference | Must be star-connected to input/output capacitor grounds to minimize ground bounce-induced ripple |
| 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; must be decoupled with ≥33µF low-ESR capacitor near pin |
| VFB (Pin 7) | Dual-mode feedback input | Grounded for 5V fixed output; connected to external divider for adjustable outputs (1.3V–VIN) |
| SHDN (Pin 8) | Active-low shutdown control | Pulled below 0.8V disables LX; pulled above 2.0V enables regulation; 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 low-battery detector | 1.28V precision reference with independent LBI input and open-drain LBO output active in shutdown |
| Internal 1A PMOS power switch | Eliminates external MOSFET; reduces BOM count and layout complexity for ≤225mA applications |
| Fixed 5V or adjustable output | Zero-component 5V operation (VFB grounded); 1.3V–VIN adjustment via two external resistors |
| Ultra-low 10µA quiescent current | Enables >10-year battery life in always-on monitoring circuits powered by 9V alkaline cells |
Applications
| 9V Battery to 5V Conversion | High-Efficiency Linear Regulator Replacement |
|---|---|
Use Scenario: Powering microcontrollers, sensors, or RF modules from standard 9V alkaline or lithium batteries in handheld test equipment. IC Role / Device Role / Timing Role: Primary step-down regulator delivering regulated 5V at up to 225mA with PFM efficiency scaling from µA to mA loads. Use Value: Extends battery life 3× over LM7805-based solutions due to 10µA IQ and >85% mid-load efficiency. |
Use Scenario: Replacing inefficient 78L05 linear regulators in space-constrained industrial controllers where thermal dissipation is critical. IC Role / Device Role / Timing Role: Drop-in DC-DC replacement providing same 5V output but with dynamic switching instead of dissipative regulation. Use Value: Reduces power loss from 1.5W (at 100mA, 9V→5V) to 0.2W, eliminating heatsink requirement. |
| Portable Instrumentation | 5V-to-3.3V Point-of-Load Conversion |
Use Scenario: Powering mixed-signal data acquisition front-ends in battery-operated oscilloscopes or multimeters requiring clean 5V analog and digital rails. IC Role / Device Role / Timing Role: Main system regulator with integrated LBI/LBO enabling battery-gauge functionality and graceful shutdown. Use Value: Combines regulation and battery monitoring in one SO-8 device, saving PCB area vs. discrete comparator + LDO solution. |
Use Scenario: Generating 3.3V for microcontroller I/O or communication peripherals from an existing 5V system rail. IC Role / Device Role / Timing Role: Secondary buck converter configured with external feedback divider (R3/R4) to deliver precise 3.3V output. Use Value: Achieves 3.3V at 150mA with <15mV ripple using 100µH inductor and 100µF/0.1µF output filter - lower noise than switching controllers without integrated FET. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar step-down DC-DC regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| MAX640ESA+T | Fixed 3.3V output; identical pinout, package, and PFM architecture; shares same 4–11.5V input range and 10µA IQ | Used where 3.3V logic rails are required instead of 5V; not interchangeable without board-level resistor changes for feedback | Select MAX640ESA+T only when system requires 3.3V output; pin-compatible but functionally distinct output voltage |
| TPS62231DRVR | 3MHz PWM converter (vs. PFM); 2.05–6.0V input; 5V output; 25µA IQ; 300mA output; 6-pin WSON package | Better transient response and lower output ripple than MAX639ESA+T, but higher light-load IQ and no integrated low-battery detector | Choose TPS62231DRVR for high-frequency, low-ripple applications with stable input; retain MAX639ESA+T for ultra-low-IQ battery monitoring use cases |
Compared with MAX640ESA+T, the MAX639ESA+T provides 5V instead of 3.3V output with identical efficiency, temperature range, and feature set. Against TPS62231DRVR, MAX639ESA+T trades higher ripple and slower transients for 2.5× lower quiescent current and integrated battery monitoring - critical for long-life portable systems.
Availability
MAX639ESA+T is available at Aetrix Electronics and suitable for portable instrumentation, battery-powered telemetry, and industrial controller power supplies requiring stable component supply, extended temperature operation, and integrated low-battery detection.
Supply support for MAX639ESA+T 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 MAX639ESA+T belongs to Maxim's legacy high-efficiency, low-IQ DC-DC converter family designed specifically for battery-powered portable equipment requiring long operational life, compact size, and integrated power supervision functions.
FAQ
What is the guaranteed output voltage tolerance for MAX639ESA+T?
The MAX639ESA+T guarantees 5.00V output within ±2% (4.90V to 5.10V) across full temperature and load range, verified by correlation to measured switch on-resistance, timing parameters, and feedback threshold. This specification applies to the MAX639ESA+T variant with internal 5V feedback divider enabled via grounded VFB pin.
Can MAX639ESA+T operate from a 3.6V lithium-ion cell?
No - the MAX639ESA+T has 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 and will not sustain regulation. For single-cell Li-ion inputs, consider the MAX640ESA+T (3.3V) or adjustable variants like MAX653ESA+T (3.0V) which specify down to 3.5V minimum input.
Does MAX639ESA+T require an external Schottky diode?
Yes - the MAX639ESA+T requires an external Schottky diode (e.g., 1N5817 or equivalent) connected between LX and VOUT to provide the freewheeling path during switch-off. The internal PMOS switch lacks body-diode conduction capability, and omitting the diode will cause catastrophic failure under load.
How does the low-battery detector behave during shutdown mode?
The low-battery detector remains fully active during shutdown: LBI continues monitoring input voltage, and LBO asserts low when LBI drops below 1.28V regardless of SHDN state. This allows battery status monitoring even when the main regulator is disabled - a key design feature confirmed in the Applications Information section.
What is the maximum recommended inductor value for MAX639ESA+T?
The datasheet specifies no upper limit, but practical maximum inductance is constrained by startup time and light-load efficiency. For 100mA loads, 470µH yields optimal efficiency (Figure MAX639-06); values beyond 1000µH increase startup delay and reduce PFM responsiveness. Inductors ≥100µH are mandatory to limit peak current to ≤600mA per Equation (3).
MAX639ESA+T Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Series:
- -
- Package/Case:
- 8-SOIC (0.154", 3.90mm Width)
- Packaging:
- Tape & Reel (TR)
- 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 (5V)
- Voltage - Output (Max):
- 11.5V
- Current - Output:
- 225mA
- Frequency - Switching:
- -
- Synchronous Rectifier:
- No
- Operating Temperature:
- -40°C ~ 85°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 8-SOIC
MAX639ESA+T FAQ
1.How can I place an order for MAX639ESA+T through Aetrix?
Please submit a Request for Quotation (RFQ) for MAX639ESA+T 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 MAX639ESA+T reliable?
The price and inventory of MAX639ESA+T are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MAX639ESA+T is usually 5 days.
3.What payment methods are accepted for MAX639ESA+T?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MAX639ESA+T transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for MAX639ESA+T?
MAX639ESA+T orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your MAX639ESA+T 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 MAX639ESA+T?
For technical support, including MAX639ESA+T datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MAX639ESA+T requirements.
6.How does Aetrix verify that MAX639ESA+T is sourced from the original manufacturer or authorized distributors?
All MAX639ESA+T 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 MAX639ESA+T meets industry standards.
7.What is the process for return or replacement of MAX639ESA+T?
All MAX639ESA+T units undergo pre-shipment inspection (PSI). If there is an issue with MAX639ESA+T, 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 MAX639ESA+T part is unused and in its original packaging.
Return procedure for MAX639ESA+T:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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