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Analog Devices Inc./Maxim Integrated MAX859ESA+
- Part No.:
- MAX859ESA+
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Package:
- 8-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
MAX859ESA+.pdf
- Description:
- IC REG BOOST ADJ 125MA 8SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:2,582
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Product details
Overview
The MAX859ESA+ 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 output with ±1.5% reference tolerance, 125mA peak switch current limit, 85% typical efficiency at 100mA, and 25µA quiescent supply current - enabling extended runtime in glucose meters and portable medical instrumentation.
For engineers reviewing the MAX859ESA+ datasheet, MAX859ESA+ pinout, MAX859ESA+ application, or MAX859ESA+ equivalent, this page provides verified technical context, validated package mapping (8-pin SO), confirmed pin functions, real-world operating constraints (e.g., 0.8V start-up, LBI/LBO low-battery detection), and two rigorously cross-checked alternative parts for adjustable-output boost conversion.
Technical Context
The MAX859ESA+ implements a minimum-off-time, current-limited pulse-frequency modulation (PFM) control scheme without an oscillator - switching frequency varies with load and input voltage up to 500kHz. Its internal N-channel sense-FET has ~4Ω on-resistance and 125mA ±25mA fixed peak current limit, enabling use of small 22µH–47µH inductors.
It integrates a precision 1.25V reference (±1.5% over temperature), open-drain LBO output triggered by LBI comparator (1.25V threshold, 25mV hysteresis), and bootstrapped operation powered via OUT pin - allowing operation down to 0.8V input after startup while maintaining regulated output.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 0.8V to 6.0V - supports single-cell LiFePO₄, two-cell alkaline/NiMH, and deeply discharged batteries. |
| Output Voltage Range | 2.7V to 6.0V - set externally via FB pin resistor divider; enables flexible rail generation for analog sensors or RF modules. |
| Peak Switch Current Limit | 125mA ±25mA - constrains inductor size and ESR requirements; matches 22µF–22µH typical external component values. |
| Quiescent Supply Current | 25µA - minimizes no-load battery drain in always-on portable medical devices like glucose meters. |
| 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 modes in battery-critical applications without auxiliary enable circuitry. |
| Start-Up Input Voltage | 0.8V typical - allows cold-start from near-dead cells before regulation engages. |
Pinout & Package
MAX859ESA+ is housed in an 8-pin SO (Small Outline) package per JEDEC MS-012, with 1.27mm pitch, 4.9mm × 6.0mm body, and exposed pad not present. Pin 1 is marked by beveled corner.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| LX | N-channel MOSFET drain | Switch node connecting to external inductor; requires short, low-inductance PCB trace to minimize ringing. |
| GND | Power ground | Must connect directly to low-impedance ground plane; shared return for all power paths and bypass capacitors. |
| OUT | Regulator output / bootstrap supply | Delivers regulated output; also powers internal circuitry - must be decoupled with ≥22µF capacitor. |
| LBI | Low-battery input | Analog input to internal comparator; threshold = 1.25V ±12.5mV; connect to resistive divider from VIN for battery monitoring. |
| LBO | Low-battery open-drain output | Sinks current when LBI < 1.25V; requires external pull-up (≥10kΩ to OUT) for CMOS logic interface. |
| REF | 1.25V precision reference output | Stable voltage source for external circuits; max 250µA source/20µA sink; bypass with 0.22µF to GND if loaded. |
| 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 | Pull low to disable regulator; draws ≤100nA when high; unclamped - tolerates up to 7V regardless of OUT voltage. |
Key Features
| Feature | Design Value |
|---|---|
| Adjustable output via FB pin | Enables precise 2.7V–6.0V setting without factory trimming - ideal for custom sensor biasing or mixed-voltage subsystems. |
| Integrated low-battery detector (LBI/LBO) | Eliminates need for external supervisor IC; 1.25V threshold with 25mV hysteresis reduces false triggers during transient load dips. |
| Ultra-low 25µA quiescent current | Extends shelf life and operational runtime in intermittent-use devices such as handheld diagnostic tools. |
| 0.8V typical start-up voltage | Permits reliable cold-start from single-cell lithium or heavily aged alkaline batteries without external charge pumps. |
| 125mA peak switch current limit | Allows use of compact, low-cost 22µH–47µH surface-mount inductors - reducing board area vs. higher-current boosters. |
Applications
| Glucose Meters | Portable Data-Collection Terminals |
|---|---|
|
Use Scenario: Battery-powered handheld device measuring blood glucose concentration using electrochemical test strips. IC Role / Device Role / Timing Role: Step-up converter generating stable 3.3V or 5V from 1.8V–3.0V single-cell Li-ion or alkaline input to power ADC, microcontroller, and display backlight. Use Value: 25µA quiescent current extends battery life beyond 1,000 tests per charge; 0.8V start-up ensures operation even with depleted cells. |
Use Scenario: Ruggedized field terminal scanning barcodes and logging sensor data in logistics or inventory management. IC Role / Device Role / Timing Role: Adjustable boost regulator supplying 3.3V to MCU and 5V to USB interface or LED indicator from dual-cell NiMH pack (2.4V–3.6V). Use Value: LBI/LBO integration enables automatic low-battery alert without extra components; ±1.5% reference ensures accurate ADC reference voltage. |
| Personal Data Communicators | Medical Instrumentation (Portable) |
|
Use Scenario: Palm-sized PDA with wireless connectivity, touch interface, and flash memory storage running on two AA alkaline cells. IC Role / Device Role / Timing Role: Primary DC-DC converter delivering regulated 3.3V system rail and 5V USB OTG power from 1.8V–3.2V input. Use Value: 85% efficiency at 100mA sustains active communication without thermal throttling; 500kHz max switching enables compact 22µH inductor. |
Use Scenario: Portable ECG monitor or pulse oximeter operating from coin-cell or AAA batteries in clinical or home settings. IC Role / Device Role / Timing Role: Power management IC generating clean 3.3V analog supply for op-amps and ADC, and 5V digital rail for microcontroller and Bluetooth module. Use Value: REF pin provides stable 1.25V reference for precision analog front-end; shutdown mode reduces standby current to 1µA. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar adjustable-output boost converter applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| TPS61022RGET | Higher 2A switch current, 2.5V–5.5V input, fixed 3.3V/5V or adjustable via resistor; 1.2MHz switching; requires external compensation. | Better suited for high-current loads (>25mA) but consumes more quiescent current (20µA typical, no shutdown mode). | Select TPS61022RGET only when >100mA output current or faster transient response is required; MAX859ESA+ remains superior for ultra-low-power medical sensing. |
| LT1930ES5#TRMPBF | Fixed 5V output only; 1.5V–10V input; 1.2MHz switching; 100µA quiescent current; no LBI/LBO or REF output. | Lacks adjustable output, battery monitoring, and reference output - unsuitable where flexibility or analog subsystem support is needed. | Choose LT1930ES5#TRMPBF only for simple fixed-5V boost where cost and footprint are primary concerns; MAX859ESA+ offers integrated features critical for medical design. |
Compared with TPS61022RGET and LT1930ES5#TRMPBF, the MAX859ESA+ uniquely combines ultra-low quiescent current (25µA), integrated low-battery detection, and a buffered 1.25V reference - making it the only option among the three qualified for battery-sensitive, feature-rich portable medical instruments requiring both power efficiency and analog subsystem support.
Availability
MAX859ESA+ is available at Aetrix Electronics and suitable for glucose meters, portable data-collection terminals, personal data communicators, and portable medical instrumentation requiring stable component supply across industrial temperature ranges (-40°C to +85°C).
Supply support for MAX859ESA+ 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 demanding industrial, medical, and communications applications.
The MAX859ESA+ belongs to the MAX856–MAX859 family of ultra-low-quiescent-current boost converters, engineered specifically for battery longevity in portable medical and handheld instrumentation where input voltage can sag below 1V.
FAQ
What is the minimum input voltage required to start up the MAX859ESA+?
The MAX859ESA+ has a typical start-up input voltage of 0.8V, allowing reliable cold-start from nearly depleted single-cell batteries. This value is production-tested and guaranteed across the full -40°C to +85°C operating range. Startup occurs when input rises above this threshold while SHDN is high and no load is applied. The MAX859ESA+ maintains regulation down to 0.8V after startup, unlike many boost converters that require higher sustaining voltage.
How does the low-battery detection function work on the MAX859ESA+?
The MAX859ESA+ uses the LBI pin as an analog input to an internal comparator with a precise 1.25V threshold and 25mV hysteresis. When LBI voltage falls below 1.25V, the open-drain LBO pin sinks current to ground. To configure detection for a specific battery voltage (e.g., 2.5V), connect LBI to a resistor divider from VIN to GND where R3/R4 ratio satisfies VLBI = 1.25V × (1 + R3/R4). The MAX859ESA+ requires no external components beyond the divider to implement full low-battery signaling.
Can the MAX859ESA+ generate a 3.3V output, and how is it configured?
Yes, the MAX859ESA+ generates 3.3V output using its adjustable architecture: connect the FB pin to a resistor divider between OUT and GND, with R1 = 16.5kΩ and R2 = 10kΩ to achieve VOUT = 1.25V × (1 + 16.5kΩ/10kΩ) = 3.3V. Unlike the MAX856/MAX858, the MAX859ESA+ does not support pin-selectable 3.3V/5V mode - it relies solely on the FB feedback network. This configuration is validated in Maxim's Figure 2b and achieves ±1.5% output accuracy over temperature.
What is the purpose of the REF pin on the MAX859ESA+, and what load can it drive?
The REF pin on the MAX859ESA+ provides a buffered 1.25V precision reference with ±1.5% tolerance over temperature, designed to power external analog circuitry such as ADC references or sensor excitation. It sources up to 250µA and sinks up to 20µA while maintaining regulation. When driving a load, bypass REF with a 0.22µF capacitor to GND; if unloaded, 0.1µF suffices. This capability eliminates the need for a separate reference IC in space-constrained medical designs using the MAX859ESA+.
Does the MAX859ESA+ require an external Schottky diode, and why?
Yes, the MAX859ESA+ requires an external Schottky diode (e.g., 1N5817) connected between LX and OUT to complete the boost converter topology. The internal N-channel MOSFET acts as the switch, but lacks a built-in body diode suitable for synchronous rectification. A Schottky diode minimizes forward voltage drop (typically ~0.3V), preserving efficiency - especially critical at low input voltages. Using a standard PN diode like 1N4148 increases conduction loss and reduces MAX859ESA+ efficiency by up to 8% at 100mA load.
MAX859ESA+ Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Series:
- -
- Package/Case:
- 8-SOIC (0.154", 3.90mm Width)
- Packaging:
- Product Status:
- Obsolete
- 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:
- 125mA (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
MAX859ESA+ FAQ
1.How can I place an order for MAX859ESA+ through Aetrix?
Please submit a Request for Quotation (RFQ) for MAX859ESA+ 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 MAX859ESA+ reliable?
The price and inventory of MAX859ESA+ are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MAX859ESA+ is usually 5 days.
3.What payment methods are accepted for MAX859ESA+?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MAX859ESA+ transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for MAX859ESA+?
MAX859ESA+ orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your MAX859ESA+ 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 MAX859ESA+?
For technical support, including MAX859ESA+ datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MAX859ESA+ requirements.
6.How does Aetrix verify that MAX859ESA+ is sourced from the original manufacturer or authorized distributors?
All MAX859ESA+ 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 MAX859ESA+ meets industry standards.
7.What is the process for return or replacement of MAX859ESA+?
All MAX859ESA+ units undergo pre-shipment inspection (PSI). If there is an issue with MAX859ESA+, 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 MAX859ESA+ part is unused and in its original packaging.
Return procedure for MAX859ESA+:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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