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Analog Devices Inc./Maxim Integrated MAX640ESA-T
- Part No.:
- MAX640ESA-T
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Package:
- 8-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
MAX640ESA-T.pdf
- Description:
- IC REG BUCK ADJ/1.3V 225MA 8SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:4,980
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Product details
Overview
MAX640ESA-T 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 MAX640ESA-T datasheet, MAX640ESA-T pinout, MAX640ESA-T application, or MAX640ESA-T equivalent, key selection criteria include its 3.3V preset output, -40°C to +85°C temperature range in 8-pin SO package, PFM efficiency at light loads, and integrated low-battery comparator functionality.
Technical Context
The MAX640ESA-T uses current-limiting pulse-frequency-modulated (PFM) control to maintain high efficiency across load currents from 10µA to 225mA, avoiding the higher quiescent current of PWM converters. Its internal 1A PMOS switch eliminates external FET requirements.
It implements dual-mode feedback via VFB: grounding VFB selects the factory-trimmed 3.3V output; connecting VFB to an external resistor divider enables adjustable operation. The low-battery detector operates independently with 1.28V threshold and remains active during shutdown.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Voltage | Fixed 3.3V ±3% (guaranteed over full temp/load range) |
| Input Voltage Range | 4.0V to 11.5V - supports single 9V battery or multi-cell Li-ion inputs |
| Max Output Current | 225mA - sufficient for microcontrollers, sensors, and RF modules |
| Quiescent Current | 10µA typical - enables >1-year battery life in always-on monitoring systems |
| Efficiency | Up to 89% at 100mA - achieved via PFM control and low RDS(ON) internal switch |
| Operating Temp | -40°C to +85°C - qualified for industrial and extended-temperature embedded use |
| Low-Battery Threshold | 1.28V ±2% on LBI - provides precise undervoltage warning before system reset |
Pinout & Package
MAX640ESA-T is housed in an 8-pin SO (Small Outline Integrated Circuit) package per JEDEC MS-012, 150-mil body width, with gull-wing leads and exposed pad not present.
| 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 signaling |
| LBI | Low-battery input reference | Compares against internal 1.28V bandgap; sets detection threshold via external resistor divider |
| GND | Power and signal ground reference | Must be connected to PCB star ground point near input/output capacitors to minimize ground bounce |
| LX | PMOS switch drain terminal | Drives external inductor; peak current limited to 600mA; requires Schottky catch diode |
| V+ | Positive supply input | Accepts 4–11.5V; must be decoupled with ≥33µF low-ESR capacitor close to pin |
| VFB | Dual-mode feedback input | Grounded for 3.3V fixed output; used with resistor divider for adjustable outputs (1.3V–V+) |
| SHDN | 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 |
|---|---|
| PFM control architecture | Enables 10µA quiescent current and >80% efficiency down to 10µA load - critical for battery longevity |
| Integrated 1A PMOS switch | Eliminates need for external high-side FET and gate driver - reduces BOM count and layout area |
| Factory-trimmed 3.3V output | Guaranteed ±3% accuracy over -40°C to +85°C without external resistors - simplifies design validation |
| Always-active low-battery detector | Operates in shutdown mode with 25µs response - enables reliable battery monitoring during sleep states |
| SO-8 package compatibility | Standard footprint allows drop-in replacement with other Maxim step-down regulators (e.g., MAX639/MAX653 variants) |
Applications
| Handheld Test Equipment | Industrial Sensor Node |
|---|---|
Use Scenario: Portable multimeter powered by 9V alkaline battery requiring stable 3.3V rail for MCU and ADC. IC Role / Device Role / Timing Role: Primary 9V-to-3.3V step-down regulator with integrated low-battery warning to trigger display alert. Use Value: 10µA IQ extends battery life beyond 500 hours of intermittent use; PFM maintains >85% efficiency at 1mA sensor bias current. | Use Scenario: Wireless temperature/humidity sensor node using AA batteries and LoRaWAN transceiver. IC Role / Device Role / Timing Role: Main power supply for 3.3V microcontroller and analog front-end; LBO signals host MCU when battery drops below 6.2V. Use Value: Fixed 3.3V output eliminates trimming resistors; SO-8 package enables compact 2-layer PCB layout with minimal thermal pads. |
| Medical Point-of-Care Device | POS Terminal Peripheral |
Use Scenario: Battery-backed glucose meter with LCD and USB charging circuitry. IC Role / Device Role / Timing Role: Supplies regulated 3.3V to display controller and precision analog signal chain; SHDN controlled by system power manager. Use Value: Shutdown current <1µA prevents battery drain during storage; LBI/LBO interface provides deterministic battery state reporting. | Use Scenario: Credit card reader module powered from 5V USB host but requiring isolated 3.3V for secure element. IC Role / Device Role / Timing Role: Standalone 5V-to-3.3V buck converter with no dependency on host processor GPIOs. Use Value: Input range includes 5V USB (±10%) and tolerates 5.5V surge; 225mA output supports simultaneous NFC and secure IC operation. |
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 |
|---|---|---|---|
| MAX639ESA-T | Fixed 5.0V output; identical pinout, package, and electrical specs except VOUT and internal feedback ratio | Used where 5V logic or legacy peripherals require non-3.3V supply; not suitable for 3.3V-only systems | Select MAX639ESA-T only when 5V output is required - same layout, no redesign needed |
| MAX653ESA-T | Fixed 3.0V output; shares all timing, efficiency, and shutdown characteristics; differs only in output voltage trim | Preferred for 3.0V microcontrollers or low-power memory interfaces; lower dropout margin than 3.3V version | Choose MAX653ESA-T for 3.0V core supplies; verify minimum input voltage (4.0V) meets system brownout threshold |
Compared with MAX639ESA-T and MAX653ESA-T, the MAX640ESA-T provides the optimal 3.3V output for modern mixed-signal SoCs and wireless transceivers, balancing headroom for noise margin and efficiency across common battery discharge curves.
Availability
MAX640ESA-T is available at Aetrix Electronics and suitable for handheld test equipment, industrial sensor nodes, medical point-of-care devices, and POS terminal peripherals requiring stable component supply with guaranteed long-term availability.
Supply support for MAX640ESA-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) designs precision analog, mixed-signal, and power management ICs for industrial, medical, and communications applications.
The MAX639/MAX640/MAX653 family delivers ultra-low-quiescent-current step-down conversion for battery-critical systems, emphasizing PFM efficiency, integrated protection, and minimal external component count.
FAQ
What is the guaranteed output voltage tolerance for MAX640ESA-T over temperature?
The MAX640ESA-T guarantees 3.3V output within ±3% over the full -40°C to +85°C operating range, as verified by production testing of the internal voltage divider and feedback comparator. This specification holds under all load conditions from 0mA to 225mA and input voltages from 4.0V to 11.5V. The MAX640ESA-T achieves this stability through factory laser-trimming of the feedback network during wafer sort.
Can MAX640ESA-T operate with input voltage below 4.0V?
No - the MAX640ESA-T has a 4.0V absolute minimum input voltage specified in its Absolute Maximum Ratings and Electrical Characteristics tables. Operation below 4.0V may result in unregulated output, failure to start, or undefined behavior of the low-battery comparator. For sub-4V applications, consider the MAX861 or MAX1722 families, which support down to 0.7V input.
Does MAX640ESA-T require an external Schottky diode, and what is the recommended part?
Yes - the MAX640ESA-T requires an external Schottky diode connected between LX and VOUT to provide the freewheeling path during switch off-time. The 1N5817 is the manufacturer-recommended part (VF ≈ 0.55V, IF = 1A), but surface-mount equivalents like SE014 (SOT-89) or SD103CWS (SOD-123) are valid alternatives. Avoid general-purpose rectifiers (e.g., 1N4001) due to slow recovery causing excessive losses.
How does the low-battery detector behave during shutdown mode of MAX640ESA-T?
The low-battery detector in the MAX640ESA-T remains fully operational during shutdown mode: LBI continues sampling the external voltage divider, and LBO will assert (pull low) whenever LBI falls below 1.28V, independent of SHDN state. This allows continuous battery monitoring while the main regulator is disabled, enabling wake-up triggers or user alerts without consuming additional system power.
What is the maximum allowable inductor value for stable operation of MAX640ESA-T?
The MAX640ESA-T does not specify a maximum inductor value, but practical stability limits arise from start-up time and light-load regulation. Inductors above 470µH increase start-up delay (e.g., >30ms at 25mA load) and may cause output overshoot during transient recovery. For optimal performance across 0–225mA loads, Maxim recommends 100µH (for highest current) or 470µH (for highest efficiency at light loads), both with ≥600mA saturation rating.
MAX640ESA-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:
- 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:
- -40°C ~ 85°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 8-SOIC
MAX640ESA-T FAQ
1.How can I place an order for MAX640ESA-T through Aetrix?
Please submit a Request for Quotation (RFQ) for MAX640ESA-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 MAX640ESA-T reliable?
The price and inventory of MAX640ESA-T are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MAX640ESA-T is usually 5 days.
3.What payment methods are accepted for MAX640ESA-T?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MAX640ESA-T transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for MAX640ESA-T?
MAX640ESA-T orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your MAX640ESA-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 MAX640ESA-T?
For technical support, including MAX640ESA-T datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MAX640ESA-T requirements.
6.How does Aetrix verify that MAX640ESA-T is sourced from the original manufacturer or authorized distributors?
All MAX640ESA-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 MAX640ESA-T meets industry standards.
7.What is the process for return or replacement of MAX640ESA-T?
All MAX640ESA-T units undergo pre-shipment inspection (PSI). If there is an issue with MAX640ESA-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 MAX640ESA-T part is unused and in its original packaging.
Return procedure for MAX640ESA-T:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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