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Analog Devices Inc./Maxim Integrated MAX640ESA+
- Part No.:
- MAX640ESA+
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Package:
- 8-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
MAX640ESA+.pdf
- Description:
- IC REG BUCK ADJ/1.3V 225MA 8SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:235
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Product details
Overview
The MAX640ESA+ 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 over 4V–11.5V input range. It integrates low-battery detection (1.28V threshold) and operates in pulse-frequency-modulated (PFM) mode for ultra-low IQ performance in portable instrumentation and battery-powered 5V-to-3.3V conversion.
For engineers reviewing the MAX640ESA+ datasheet, MAX640ESA+ pinout, MAX640ESA+ application, or MAX640ESA+ equivalent, this page delivers verified electrical parameters, SOIC-8 package layout, confirmed low-battery comparator behavior, and validated alternative options for 3.3V buck conversion in space-constrained industrial and handheld systems.
Technical Context
The MAX640ESA+ uses a variable-frequency, duty-cycle-controlled PFM architecture that dynamically adjusts tON and tOFF per Equations (1) and (2) to maintain constant peak inductor current across input voltage variations. Its error comparator drives an on-demand oscillator only when output regulation is required, minimizing no-load supply current.
It features dual-mode feedback via VFB: grounding VFB selects the factory-trimmed 3.3V output; connecting VFB to an external resistor divider enables adjustable operation down to 1.3V. The low-battery detector remains active during shutdown, with LBI/LBO pins supporting independent 1.28V threshold monitoring.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Voltage | Fixed 3.3V ±3% (2.88V–3.12V), guaranteed by correlation to switch timing and feedback threshold |
| Input Voltage Range | 4.0V to 11.5V - supports 9V battery, 5V rail, or wide-input industrial supplies |
| Max Output Current | 225mA at VIN ≥ 5.5V with 100µH inductor - sufficient for microcontrollers and sensors |
| Quiescent Current | 10µA typical (SHDN = V+, no load) - enables multi-year battery life in standby |
| Efficiency | Up to 89% at 100mA, 9V input - exceeds linear regulators under medium loads |
| Switch On-Resistance | 0.8Ω typical - limits dropout and conduction loss at full load |
| Low-Battery Threshold | 1.28V ±0.02V on LBI - precise undervoltage warning for Li-ion or alkaline cells |
Pinout & Package
MAX640ESA+ is housed in an 8-pin SOIC (SO) package, 3.94mm × 4.90mm body, 1.27mm pitch, with exposed pad not present. Pin 1 marked by notch or dot.
| 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 2.5mA when LBI < 1.28V; requires external pull-up for logic-level signaling |
| LBI | Low-battery input comparator | Monitors external voltage divider; reference is internal 1.28V bandgap - active in shutdown |
| GND | Power and signal ground 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 - requires Schottky catch diode |
| V+ | Positive input supply | Accepts 4V–11.5V; absolute max 12V - decoupling capacitor mandatory at pin |
| VFB | Dual-mode feedback input | Grounded → 3.3V fixed output; externally biased → adjustable output (1.3V–VIN) |
| SHDN | Active-low shutdown control | <0.8V → shutdown (LX high-Z); >2.0V → enabled; tie to V+ if unused |
Key Features
| Feature | Design Value |
|---|---|
| Pulse-frequency modulation (PFM) | Enables 10µA quiescent current and >85% efficiency at 1mA load - critical for battery longevity |
| Integrated 1A PMOS switch | Eliminates external MOSFET and gate driver - reduces BOM count and PCB area in compact designs |
| Factory-trimmed 3.3V output | ±3% tolerance without external resistors - simplifies design-in for standard logic rails |
| Independent low-battery monitor | 1.28V threshold with 25µs response - provides early warning before system brownout |
| Shutdown mode with active LBI/LBO | Maintains battery monitoring while consuming zero switching current - ideal for wake-on-low-voltage |
Applications
| Portable Instrument Power | Handheld Terminal Conversion |
|---|---|
Use Scenario: Battery-powered multimeter with LCD, microcontroller, and analog front-end requiring clean 3.3V rail from 9V PP3 battery. IC Role / Device Role / Timing Role: Primary step-down regulator delivering regulated 3.3V at up to 225mA; LBO triggers display alert when battery drops below 6.8V. Use Value: 10µA quiescent current extends shelf life; PFM operation maintains >80% efficiency from 1mA to full load. | Use Scenario: Ruggedized barcode scanner using dual AA cells (2.4V–3.2V) needing stable 3.3V for CMOS image sensor and ARM Cortex-M0. IC Role / Device Role / Timing Role: Inverting buck converter (Figure 6 topology) generating -3.3V referenced to battery ground - enabling efficient 3.3V system rail. Use Value: Internal PMOS switch + inverter configuration achieves >85% efficiency at 10mA with 470µH inductor - avoids external level-shifting. |
| 5V-to-3.3V Point-of-Load | High-Efficiency Linear Regulator Replacement |
Use Scenario: Industrial PLC I/O module with existing 5V backplane supplying 3.3V to isolated CAN transceivers and ADCs. IC Role / Device Role / Timing Role: Fixed-output buck converter replacing inefficient 5V-to-3.3V LDO; LX switching synchronized to system clock edge to reduce EMI coupling. Use Value: 89% efficiency at 100mA cuts thermal dissipation by 75% vs. LDO - eliminates heatsink in sealed enclosure. | Use Scenario: Legacy medical sensor node designed with LM1117-3.3 but suffering thermal derating above 150mA at 5V input. IC Role / Device Role / Timing Role: Drop-in replacement buck regulator maintaining same footprint and output capacitor; SHDN pin used for MCU-controlled power gating. Use Value: Delivers full 225mA at ambient temperature with <1°C rise - enables continuous sampling without thermal throttling. |
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 | Higher frequency enables smaller inductors/caps; no integrated LBO/LBI comparator | Select when board space is constrained and battery monitoring is handled elsewhere |
| LT1930ES5#TRMPBF | 3.3V fixed, 250mA output, 3.6V–36V input, 100µA IQ, 1.25MHz PWM | Wider input range and higher voltage rating; no low-battery detection; SOT-23-5 package | Select for automotive or industrial inputs >12V where extended VIN range outweighs IQ penalty |
Compared with TPS62231DRYR and LT1930ES5#TRMPBF, the MAX640ESA+ uniquely combines ultra-low 10µA quiescent current, integrated low-battery monitoring, and SOIC-8 manufacturability - making it optimal for cost-sensitive, battery-critical portable instruments where feature integration trumps miniaturization.
Availability
MAX640ESA+ is available at Aetrix Electronics and suitable for portable instrumentation, handheld terminals, and 5V-to-3.3V point-of-load conversion requiring stable component supply across industrial temperature ranges.
Supply support for MAX640ESA+ 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, medical, and communications markets.
The MAX640ESA+ belongs to Maxim's legacy high-efficiency, low-IQ DC-DC converter family, engineered specifically for battery-powered portable equipment where long operating life and minimal external components are essential.
FAQ
What is the guaranteed output voltage tolerance for MAX640ESA+?
The MAX640ESA+ guarantees a 3.3V output within ±3% (2.88V to 3.12V) over temperature and load, as confirmed by correlated measurements of switch on-resistance, on/off times, and feedback threshold - not just initial trim. This specification applies across the full –40°C to +85°C operating range with 4V–11.5V input and 0–225mA load.
Does MAX640ESA+ support adjustable output voltage?
Yes, the MAX640ESA+ supports adjustable output via the VFB pin. When VFB is left unconnected or biased with an external resistor divider, the output can be set from 1.3V up to the input voltage. The formula is R3 = R4 × [(VOUT/1.28V) – 1], where R4 is typically 100kΩ. The MAX640ESA+ retains its 3.3V factory-trimmed accuracy only when VFB is grounded.
Can MAX640ESA+ operate with input voltage below 4V?
No - the absolute minimum input voltage for functional regulation is 4.0V, as specified in the Absolute Maximum Ratings and Electrical Characteristics tables. Operation below 4V may result in dropout, unregulated output, or failure to start. For sub-4V applications, consider the MAX8640Y or similar low-VIN buck converters.
Is the low-battery detector active during shutdown mode of MAX640ESA+?
Yes, the low-battery detector remains fully active during shutdown mode of the MAX640ESA+. When SHDN is pulled below 0.8V, the LX switch disables and VOUT collapses, but the internal 1.28V reference and LBI/LBO comparator continue operating - allowing continuous battery monitoring without waking the main regulator.
What is the maximum recommended inductor value for MAX640ESA+?
The MAX640ESA+ datasheet recommends inductors ≥100µH, with 100µH–470µH being typical. Larger values (e.g., 470µH) improve light-load efficiency and reduce ripple but increase start-up time and physical size. Inductor saturation current must exceed 600mA, and series resistance should be minimized to preserve dropout and efficiency - especially critical below 5V input.
MAX640ESA+ Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Series:
- -
- Package/Case:
- 8-SOIC (0.154", 3.90mm Width)
- Packaging:
- Tube
- 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+ FAQ
1.How can I place an order for MAX640ESA+ through Aetrix?
Please submit a Request for Quotation (RFQ) for MAX640ESA+ 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+ reliable?
The price and inventory of MAX640ESA+ are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MAX640ESA+ is usually 5 days.
3.What payment methods are accepted for MAX640ESA+?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MAX640ESA+ transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for MAX640ESA+?
MAX640ESA+ orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your MAX640ESA+ 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+?
For technical support, including MAX640ESA+ datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MAX640ESA+ requirements.
6.How does Aetrix verify that MAX640ESA+ is sourced from the original manufacturer or authorized distributors?
All MAX640ESA+ 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+ meets industry standards.
7.What is the process for return or replacement of MAX640ESA+?
All MAX640ESA+ units undergo pre-shipment inspection (PSI). If there is an issue with MAX640ESA+, 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+ part is unused and in its original packaging.
Return procedure for MAX640ESA+:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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