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Analog Devices Inc./Maxim Integrated MAX857ESA+
- Part No.:
- MAX857ESA+
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Package:
- 8-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
MAX857ESA+.pdf
- Description:
- IC REG BOOST ADJ 500MA 8SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:100
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Product details
Overview
The MAX857ESA+ from Maxim Integrated is an adjustable-output, step-up DC-DC switching regulator optimized for low-input-voltage battery-powered systems. It accepts 0.8V–6.0V input and delivers 2.7V–6.0V adjustable output with ±1.5% reference tolerance, 125mA peak switch current limit, and 25µA quiescent supply current-enabling extended runtime in glucose meters and portable data collectors.
For engineers reviewing the MAX857ESA+ datasheet, MAX857ESA+ pinout, MAX857ESA+ application, or MAX857ESA+ equivalent, key selection criteria include its 8-pin SO package, internal N-channel MOSFET, PFM control architecture, low-battery detection (LBI/LBO), and bootstrap power delivery via OUT pin-critical for ultra-low-voltage start-up and high-efficiency operation in space-constrained medical and handheld devices.
Technical Context
The MAX857ESA+ implements a minimum-off-time, current-limited pulse-frequency modulation (PFM) control scheme without an oscillator, enabling variable-frequency switching up to 500kHz. Its internal sense-FET MOSFET features ~4Ω on-resistance and 125mA ±25mA peak current limit, supporting compact inductor selection (e.g., 47µH).
It integrates a precision 1.25V reference (±1.5% over temperature), low-battery comparator (1.25V threshold with 25mV hysteresis), and open-drain LBO output. Power is bootstrapped from the regulated output via the OUT pin, allowing operation down to 0.8V input after start-up.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 0.8V to 6.0V - supports single-cell Li-ion, NiMH, or alkaline battery operation across full discharge curve. |
| Output Voltage Range | 2.7V to 6.0V - set externally via FB pin and resistor divider; enables flexible rail generation for analog sensors or logic. |
| Peak Switch Current Limit | 125mA ±25mA - defines maximum inductor current; permits use of small, low-cost 47µH inductors with <1Ω DCR. |
| Quiescent Supply Current | 25µA - minimizes no-load battery drain; critical for always-on medical instrumentation. |
| Reference Voltage Accuracy | ±1.5% over -40°C to +85°C - ensures stable feedback loop performance across industrial temperature range. |
| Shutdown Current | 1µA - enables deep sleep mode; reduces system standby power to sub-microwatt levels. |
| Switching Frequency | Up to 500kHz - allows compact external components while maintaining >85% efficiency at 100mA load. |
Pinout & Package
MAX857ESA+ is housed in an 8-pin SO (Small Outline) package, 3.9mm × 4.9mm, with standard JEDEC MS-012AC footprint and gull-wing leads. Thermal pad not present; GND pin (pin 6) must be soldered directly to PCB ground plane for optimal thermal and noise performance.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| LX | N-channel power MOSFET drain | Connects to inductor and Schottky diode anode; carries high-frequency switched current; requires short, low-inductance trace. |
| GND | Power ground | Main return path for switch current and IC bias; must be low-impedance connection to solid ground plane. |
| OUT | Regulated output & bootstrap supply | Delivers regulated voltage to load; also powers internal circuitry-enables operation below 1V input after start-up. |
| LBI | Low-battery input | Monitors battery voltage via external resistor divider; triggers LBO when input falls below 1.25V threshold. |
| LBO | Low-battery open-drain output | Sinks current when LBI < 1.25V; requires external pull-up to OUT or VCC for CMOS-compatible signaling. |
| REF | Precision 1.25V reference output | Stable reference for FB feedback and external circuits; max 250µA source / 20µA sink; bypass with 0.22µF to GND. |
| FB | Feedback input | Connects to resistor divider between OUT and GND; sets output voltage per VOUT = 1.25V × (1 + R1/R2). |
| SHDN | Active-low shutdown control | Pulls entire IC into 1µA standby; compatible with 0–7V logic levels; must not float. |
Key Features
| Feature | Design Value |
|---|---|
| Ultra-low 25µA quiescent current | Extends battery life in intermittent-use devices like glucose meters by minimizing idle power loss. |
| 0.8V typical start-up voltage | Enables reliable operation from deeply discharged single-cell batteries without external assist circuitry. |
| Integrated low-battery detector (LBI/LBO) | Eliminates need for external supervisor IC; provides programmable brown-out warning with 25mV hysteresis. |
| Internal 125mA current-limited N-MOSFET | Reduces BOM count and layout complexity; supports compact 47µH inductors with minimal saturation margin. |
| Bootstrap power from OUT pin | Removes dependency on input rail for internal biasing-allows VIN to sag below VREF after regulation is established. |
Applications
| Glucose Meters | Portable Data Collectors |
|---|---|
Use Scenario: Battery-powered handheld device measuring blood glucose concentration using electrochemical sensor requiring stable 3.3V or 5V analog front-end and microcontroller supply. IC Role / Device Role / Timing Role: Step-up regulator generating precise, low-noise 3.3V rail from 1.8–2.4V single alkaline cell; provides LBO signal for battery replacement alert. Use Value: 25µA quiescent current extends shelf life and field runtime; 0.8V start-up ensures functionality even with aged batteries; ±1.5% reference supports accurate ADC reference stability. |
Use Scenario: Ruggedized barcode scanner or RFID reader operating from two AA cells, requiring regulated 5V for imaging sensor and 3.3V for MCU/communication interface. IC Role / Device Role / Timing Role: Adjustable-output boost converter delivering 5.0V @ 100mA with fast transient response to pulsed sensor loads; SHDN enables host-controlled power cycling. Use Value: 500kHz switching frequency permits miniature 47µH inductor and 22µF ceramic output capacitor; integrated LBI/LBO replaces discrete comparator and saves board area. |
| Personal Digital Assistants | Medical Instrumentation |
Use Scenario: Legacy PDA with monochrome LCD and flash memory, powered by 2×AA batteries, needing 3.3V for logic and 5V for backlight driver. IC Role / Device Role / Timing Role: Dual-rail capable boost IC configured for 3.3V output; FB pin used to maintain tight regulation under varying load conditions during display updates. Use Value: 125mA peak switch current supports burst-mode backlight operation; 8-pin SO package fits tight layout constraints; -40°C to +85°C rating ensures reliability in diverse environments. |
Use Scenario: Portable ECG monitor using low-power analog front-end and Bluetooth LE radio, powered by coin-cell or AAA battery. IC Role / Device Role / Timing Role: Primary power management IC generating clean 3.3V supply for mixed-signal ASIC and RF transceiver; REF pin supplies precision voltage to ADC reference input. Use Value: ±1.5% reference tolerance over temperature guarantees consistent measurement accuracy; 1µA shutdown current preserves battery during sleep intervals between patient readings. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar step-up DC-DC converter applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| TPS61200DRCT | Fixed 3.3V output only; 1.8V–5.5V input; 1.2A switch current; 2.5MHz fixed-frequency PWM. | Higher output current but lacks adjustable output and LBI/LBO; unsuitable for low-battery monitoring. | Select when higher output current and smaller inductor size are prioritized over battery monitoring and voltage flexibility. |
| LT1945EMS8#TRPBF | Adjustable output (1.25V–15V); 0.9V start-up; 1.1A switch current; includes dual outputs (boost + inverting). | Broader voltage range and dual topology, but larger 8-MSOP package and higher 100µA quiescent current. | Select when dual-rail generation or sub-0.9V start-up is required, accepting higher idle power and larger footprint. |
Compared with TPS61200DRCT and LT1945EMS8#TRPBF, the MAX857ESA+ offers unique integration of adjustable output, ultra-low 25µA quiescent current, and dedicated low-battery detection in a compact SO-8 package-making it optimal for cost-sensitive, battery-life-critical medical and handheld applications where feature-specific functionality outweighs raw current capability.
Availability
MAX857ESA+ is available at Aetrix Electronics and suitable for glucose meters, portable data collectors, personal digital assistants, and medical instrumentation requiring stable component supply across industrial temperature ranges and long production lifecycles.
Supply support for MAX857ESA+ 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 semiconductor company specializing in high-performance analog, mixed-signal, and power management solutions for industrial, medical, and consumer applications.
The MAX856–MAX859 family was designed specifically for ultra-low-voltage, battery-powered systems requiring high efficiency and minimal quiescent current-targeting portable medical devices, handheld instruments, and energy-constrained IoT endpoints.
FAQ
What is the minimum input voltage required to start up the MAX857ESA+?
The MAX857ESA+ has a typical start-up supply voltage of 0.8V, enabling reliable operation from nearly depleted single-cell batteries. This value is confirmed across load conditions up to 25mA and is specified in the Electrical Characteristics table under "Minimum Start-Up Supply Voltage." The actual start-up voltage varies slightly with load and temperature, but remains ≤0.95V across the full -40°C to +85°C operating range. MAX857ESA+ achieves this via a low-threshold sense-FET and bootstrap architecture that draws initial bias from the output rail once regulation begins.
How does the MAX857ESA+ implement low-battery detection?
The MAX857ESA+ integrates a dedicated low-battery comparator with a precise 1.25V threshold and 25mV hysteresis. The LBI pin monitors a resistor-divider network connected to the input supply, and when the divided voltage falls below 1.25V, the open-drain LBO pin sinks current to ground. This signal can drive a microcontroller interrupt or LED indicator. The MAX857ESA+ datasheet specifies LBI input current as ±100nA, enabling high-impedance divider networks that minimize battery drain-critical for multi-year medical device deployments.
Can the MAX857ESA+ be used with ceramic output capacitors?
Yes, the MAX857ESA+ supports ceramic output capacitors, though design considerations apply. The recommended 68µF tantalum capacitor (e.g., Sprague 595D) provides optimal ESR for stability and ripple suppression. Ceramic capacitors offer lower ESR but may cause instability due to insufficient phase margin; if used, add a small series resistor (e.g., 100mΩ) or combine with a 1–10µF tantalum to maintain ≥50mΩ effective ESR. The MAX857ESA+'s PFM control tolerates moderate ESR variation, but output ripple increases proportionally to IPEAK × ESR-so low-ESR ceramics require careful layout and potential compensation.
What is the function of the OUT pin on the MAX857ESA+?
The OUT pin on the MAX857ESA+ serves a dual role: it delivers the regulated output voltage to the load and simultaneously supplies bootstrap power to the internal circuitry-including the gate driver and reference. This architecture allows the MAX857ESA+ to operate with input voltages as low as 0.8V after start-up, because internal biasing is derived from the higher output rail rather than the input. Connecting external components directly to OUT (e.g., LBO pull-up, REF bypass) is essential; the pin is not a simple output node but a critical power domain hub within the MAX857ESA+'s functional block diagram.
Is the MAX857ESA+ pin-compatible with other devices in the MAX856–MAX859 family?
No, the MAX857ESA+ is not pin-compatible with MAX856/MAX858 variants. While all share the same 8-pin SO package, the pin functions differ: MAX857/MAX859 use FB (pin 3) for feedback, whereas MAX856/MAX858 use 3/5 (pin 3) for output voltage selection. Swapping them without board revision will result in incorrect regulation or failure to start. The MAX857ESA+ pinout is identical only to MAX859ESA+, and both require external resistor dividers for output setting-unlike the fixed-output MAX856ESA+/MAX858ESA+ variants.
MAX857ESA+ 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-Up
- Output Configuration:
- Positive
- Topology:
- Boost
- Output Type:
- Adjustable
- Number of Outputs:
- 1
- Voltage - Input (Min):
- 0.8V
- Voltage - Input (Max):
- 6V
- Voltage - Output (Min/Fixed):
- 2.7V
- Voltage - Output (Max):
- 6V
- Current - Output:
- 500mA (Switch)
- Frequency - Switching:
- 500kHz
- Synchronous Rectifier:
- No
- Operating Temperature:
- -40°C ~ 85°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 8-SOIC
MAX857ESA+ FAQ
1.How can I place an order for MAX857ESA+ through Aetrix?
Please submit a Request for Quotation (RFQ) for MAX857ESA+ 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 MAX857ESA+ reliable?
The price and inventory of MAX857ESA+ are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MAX857ESA+ is usually 5 days.
3.What payment methods are accepted for MAX857ESA+?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MAX857ESA+ transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for MAX857ESA+?
MAX857ESA+ orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your MAX857ESA+ 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 MAX857ESA+?
For technical support, including MAX857ESA+ datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MAX857ESA+ requirements.
6.How does Aetrix verify that MAX857ESA+ is sourced from the original manufacturer or authorized distributors?
All MAX857ESA+ 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 MAX857ESA+ meets industry standards.
7.What is the process for return or replacement of MAX857ESA+?
All MAX857ESA+ units undergo pre-shipment inspection (PSI). If there is an issue with MAX857ESA+, 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 MAX857ESA+ part is unused and in its original packaging.
Return procedure for MAX857ESA+:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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