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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:1,402
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Product details
Overview
MAX640ESA+T from Maxim Integrated is a 3.3V fixed-output, high-efficiency step-down DC-DC switching regulator with internal 1A PMOS power switch, 10µA quiescent current, and 225mA output capability across 4V–11.5V input range. It integrates low-battery detection (LBI/LBO), shutdown control, and PFM modulation for ultra-low-power portable applications such as handheld terminals and 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 industrial temperature rating in 8-pin SO package, 1.28V feedback threshold, and compatibility with standard 100µH inductors and Schottky diodes like 1N5817.
Technical Context
The MAX640ESA+T 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 across light-to-heavy loads without external compensation. Its internal 1A PMOS switch eliminates gate-drive complexity and supports both buck and inverting configurations.
It features dual-mode feedback (VFB grounded for 3.3V fixed output or externally biased for adjustable operation), an always-active low-battery comparator referenced to 1.28V, and shutdown logic with 0.8V–2.0V hysteresis - all operating independently of regulator state, including during shutdown mode.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Voltage | Fixed 3.3V ±4% (2.88V–3.12V) at 100mA, verified over full input and temperature range |
| Input Voltage Range | 4.0V to 11.5V - supports single 9V battery, dual AA/AAA, or regulated 5V–12V rails |
| Quiescent Current | 10µA typical - enables >1-year battery life in standby for low-duty-cycle IoT sensors |
| Max Output Current | 225mA at VIN ≥ 6V with 100µH inductor - sufficient for microcontrollers, RF modules, and LCD bias supplies |
| Efficiency | 89% typical at 100mA load, 9V input - exceeds linear regulators by >4× at medium loads |
| Feedback Threshold | 1.28V ±20mV - sets precise output voltage via internal divider or external resistor network |
| Low-Battery Threshold | 1.28V on LBI pin - allows configurable brown-out detection down to ~2.5V system input |
Pinout & Package
MAX640ESA+T is housed in an 8-pin SOIC (SO) package (JEDEC MS-012, 150-mil width), with exposed pad not electrically connected. Pin spacing is 1.27mm pitch; body dimensions are 4.90mm × 3.90mm × 1.75mm (L × W × H).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VOUT | Regulated output sense node | Internally connected to feedback 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 interface |
| LBI | Low-battery comparator input | Monitors external voltage divider; remains active in shutdown for battery monitoring |
| GND | Power and signal reference | Must be star-connected with CIN, COUT, and diode anode to minimize ground bounce |
| LX | PMOS switch drain terminal | Drives external inductor; peak current limited to 600mA - dictates inductor saturation rating |
| V+ | Positive supply input | Accepts 4V–11.5V; absolute max 12V - decoupling capacitor required within 5mm |
| VFB | Dual-mode feedback input | Grounded for 3.3V fixed output; otherwise sets VOUT = 1.28V × (1 + R3/R4) |
| SHDN | Active-low enable input | Pulled below 0.8V disables LX; pulled above 2.0V enables regulation - internal 0.2µA pull-up |
Key Features
| Feature | Design Value |
|---|---|
| PFM Control Architecture | Eliminates fixed-frequency switching losses at light loads - maintains >80% efficiency down to 10µA output current |
| Integrated 1A PMOS Switch | Reduces BOM count by eliminating external MOSFET and driver; simplifies layout and improves thermal performance |
| Programmable Low-Battery Detection | Configurable trip point using two resistors - enables system-level power management without MCU intervention |
| Shutdown Mode Leakage Control | Sub-1µA total system shutdown current - preserves battery charge during extended idle periods |
| Inverting Configuration Support | Enables generation of regulated negative outputs (e.g., –3.3V) from positive input without additional ICs |
Applications
| Handheld Medical Instrument Power | Industrial Sensor Node Supply |
|---|---|
Use Scenario: Portable blood glucose meter powered by two AA alkaline cells (2.4V–3.2V), requiring clean 3.3V for MCU and analog front-end. IC Role / Device Role / Timing Role: Primary step-down regulator converting variable battery voltage to stable 3.3V; LBO triggers display alert when cell voltage drops below 2.6V. Use Value: 10µA quiescent current extends battery life to >18 months in sleep mode; PFM operation ensures consistent 3.3V accuracy across full discharge curve. | Use Scenario: Wireless temperature sensor node with LoRaWAN radio, operating from 3.6V Li-SOCl₂ battery with 10-year lifespan requirement. IC Role / Device Role / Timing Role: Main power converter supplying 3.3V to MCU and transceiver; SHDN controlled by MCU GPIO to disable power between transmissions. Use Value: Shutdown current < 1µA prevents measurable battery drain during 99.9% sleep duty cycle; 225mA peak supports radio transmit bursts. |
| Point-of-Sale Terminal Logic Supply | Embedded Display Bias Generator |
Use Scenario: Battery-backed retail terminal using 9V primary battery and supercapacitor backup, needing reliable 3.3V for ARM Cortex-M4 processor. IC Role / Device Role / Timing Role: Primary DC-DC regulator with LBI monitoring supercap voltage; LBO asserts reset signal to MCU on backup depletion. Use Value: 89% efficiency at 100mA reduces thermal load in sealed enclosure; SO package enables compact 2-layer PCB design. | Use Scenario: Automotive infotainment display requiring isolated 3.3V bias for touch controller, derived from 5V system rail. IC Role / Device Role / Timing Role: Compact buck converter mounted near display module; operates in inverting configuration to generate –3.3V for analog circuitry. Use Value: Eliminates need for isolated DC-DC module - reduces cost by $1.20/unit and saves 120mm² board area. |
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 |
|---|---|---|---|
| TPS62231DRYR | 3.3V fixed, 300mA output, 2.05V–6.5V input, 17µA IQ, 2.5MHz PWM | Better suited for space-constrained designs requiring higher current and smaller inductors; lacks LBI/LBO functionality | Select when board area is critical and battery monitoring is handled externally |
| LT1931ES5#TRMPBF | Adjustable 1.25V–30V, 1.3A switch, 4V–36V input, 100µA IQ, PFM/PWM hybrid | Higher input range and current drive, but larger solution size and higher quiescent current limits ultra-low-power use | Select for wide-input industrial systems where 10µA IQ is not mandatory |
Compared with TPS62231DRYR and LT1931ES5#TRMPBF, the MAX640ESA+T uniquely combines ultra-low 10µA quiescent current, integrated battery monitoring (LBI/LBO), and 3.3V fixed output in a legacy-proven SO-8 package - making it optimal for cost-sensitive, battery-life-critical portable instruments where feature integration outweighs footprint minimization.
Availability
MAX640ESA+T is available at Aetrix Electronics and suitable for handheld medical devices, industrial wireless sensors, point-of-sale terminals, and embedded display subsystems requiring stable component supply with long-term lifecycle support.
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) 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 MAX639/MAX640/MAX653 product line was designed specifically for ultra-low-power, minimum-component DC-DC conversion in portable and battery-operated equipment - prioritizing quiescent current, integration, and ease of use over switching frequency or footprint.
FAQ
What output voltage does the MAX640ESA+T deliver?
The MAX640ESA+T delivers a factory-trimmed fixed output voltage of 3.3V ±4% (2.88V–3.12V) when VFB is grounded. This specification is guaranteed over the full input range (4V–11.5V), load (0–225mA), and temperature (-40°C to +85°C). The MAX640ESA+T cannot be adjusted to other voltages without modifying the feedback network, and doing so voids the 3.3V guarantee.
Can the MAX640ESA+T operate from a single 3.7V Li-ion cell?
No, the MAX640ESA+T requires a minimum input voltage of 4.0V per Absolute Maximum Ratings and Electrical Characteristics tables. A single 3.7V Li-ion cell (3.0V–4.2V) falls below the 4.0V lower limit during discharge, causing dropout and regulation failure. For Li-ion applications, consider the MAX861 or MAX1722 family, which support inputs down to 0.7V.
Does the MAX640ESA+T require an external diode?
Yes, the MAX640ESA+T requires an external Schottky diode (e.g., 1N5817) connected between LX and VOUT. The internal PMOS switch lacks body-diode conduction capability in buck topology, so the external diode provides the freewheeling path during switch-off. Omitting it will cause catastrophic failure due to inductive kickback and reverse current.
How does the low-battery detection work on the MAX640ESA+T?
The MAX640ESA+T's low-battery detector compares the voltage at LBI to an internal 1.28V reference. When LBI drops below 1.28V, LBO pulls low (open-drain). LBI is typically driven by a resistor divider from V+, allowing programmable trip points (e.g., 2.6V with R1=100kΩ, R2=100kΩ). Critically, this comparator remains fully operational even when SHDN is asserted.
What is the maximum inductor value recommended for the MAX640ESA+T?
The MAX640ESA+T supports inductors from 100µH to 470µH. While larger values reduce ripple and improve light-load efficiency, they increase start-up time and physical size. The datasheet specifies 100µH as the minimum (to limit IPEAK ≤ 600mA), and 470µH as the maximum used in characterization. Inductors >470µH may cause excessive start-up delay (>10ms) and marginal stability with certain capacitors.
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:
- 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 (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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