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Analog Devices Inc./Maxim Integrated MAX859ESA
- Part No.:
- MAX859ESA
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Category:
- Special Purpose Regulators
- Package:
- 8-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
MAX859ESA.pdf
- Description:
- STEP-UP DC-DC CONVERTER
- Quantity:
- Payment:
- Shipping:
Inventory:2,194
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Product details
Overview
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, and 85% efficiency at 100mA load - enabling compact, high-efficiency power conversion 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 pin functions, confirmed operating parameters across temperature (–40°C to +85°C), and real-world design implications for low-battery detection, bootstrapped operation, and PFM control architecture.
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 starts reliably from 0.8V typical input.
It integrates a precision 1.25V reference (±1.5% over temperature), low-battery comparator (LBI/LBO), and feedback (FB) input for external resistor-divider-based output adjustment. The device is internally bootstrapped via the OUT pin, enabling operation even as battery voltage sags to 0.8V after startup.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 0.8V to 6.0V - supports single- or dual-cell alkaline/NiMH batteries down to near-dead state. |
| Output Voltage Range | 2.7V to 6.0V (adjustable via FB pin) - enables flexible rail generation for mixed-signal SoCs and sensors. |
| Peak Switch Current Limit | 125mA ±25mA - constrains inductor size and ESR selection; compatible with 22µF–47µF output capacitors. |
| Quiescent Supply Current | 25µA (typ) - extends runtime in always-on portable devices like glucose meters. |
| Shutdown Current | 1µA - ensures negligible battery drain during system sleep modes. |
| Reference Voltage Accuracy | ±1.5% over –40°C to +85°C - enables stable feedback loop performance across industrial temperature range. |
| Switching Frequency | Up to 500kHz - permits use of small 47µH surface-mount inductors and reduces filter component footprint. |
Pinout & Package
MAX859ESA is housed in an 8-pin SO (Small Outline) package, 0.150-inch wide, with lead pitch of 1.27mm and RoHS-compliant finish. Thermal resistance θJA is 5.88mW/°C above +70°C; maximum continuous power dissipation at +70°C is 471mW.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| LX | N-channel power MOSFET drain | Connects to inductor and Schottky rectifier anode; carries pulsed 125mA peak current. |
| GND | Power ground | Low-impedance return path; must be soldered directly to PCB ground plane to minimize noise and ripple. |
| OUT | Regulator output / bootstrap supply | Provides output voltage and powers internal circuitry; connects to cathode of external Schottky diode. |
| LBI | Low-battery detector input | Monitors battery voltage via resistor divider; triggers LBO when voltage falls below 1.25V threshold. |
| LBO | Low-battery open-drain output | Sinks current to GND when LBI < 1.25V; requires external pull-up (e.g., to OUT) for CMOS logic interface. |
| REF | Precision 1.25V reference output | Stable reference for external ADCs or feedback networks; bypass with 0.22µF to GND if loaded. |
| FB | Feedback input (adjustable mode) | Connects to resistor divider between OUT and GND; sets output voltage per VOUT = 1.25V × (1 + R1/R2). |
| SHDN | Active-low shutdown control | Pulls low to disable regulator; VIN drops to VIN − VF(diode); supports system-level power sequencing. |
Key Features
| Feature | Design Value |
|---|---|
| Ultra-low quiescent current | 25µA typical - preserves battery life in intermittently active medical devices. |
| Adjustable output via FB pin | 2.7V–6.0V range with ±1.5% reference accuracy - eliminates need for multiple fixed-output variants. |
| Integrated low-battery detection | LBI/LBO pair with 1.25V threshold and hysteresis - enables autonomous battery monitoring without external comparators. |
| Bootstrapped operation | Internal supply derived from OUT pin - allows start-up from 0.8V and sustained operation as battery sags. |
| PFM control architecture | No oscillator; variable-frequency switching up to 500kHz - balances light-load efficiency and EMI profile. |
Applications
| Glucose Meters | Portable Data-Collection Equipment |
|---|---|
Use Scenario: Handheld blood glucose analyzers powered by two AA alkaline cells (1.0V–3.0V range) requiring stable 3.3V for microcontroller and sensor bias. IC Role / Device Role / Timing Role: Step-up regulator providing regulated 3.3V output while maintaining >85% efficiency at 10–50mA loads and enabling shutdown during measurement idle periods. Use Value: Extends battery life beyond 500 measurements per set; 1µA shutdown current prevents overnight discharge; LBO alerts user before battery exhaustion. |
Use Scenario: Ruggedized barcode scanners and RFID readers used in field logistics, operating from 2-cell NiMH packs with voltage decay from 2.8V to 1.2V. IC Role / Device Role / Timing Role: Adjustable-output boost converter delivering 5.0V to USB-peripheral interface ICs and 3.3V to MCU core, dynamically reconfigured via firmware. Use Value: Single IC supports dual-rail needs; 125mA peak current suffices for pulsed laser/LED drivers; PFM mode maintains >80% efficiency down to 1mA load. |
| Personal Data Communicators | Medical Instrumentation |
Use Scenario: Palm-sized PDAs with integrated GPS and Bluetooth, powered by lithium coin cell (2.0V–3.0V) and requiring 3.3V for RF transceiver and 2.8V for display driver. IC Role / Device Role / Timing Role: Primary boost regulator generating 3.3V rail; FB pin used with DAC-controlled resistor network to dynamically adjust output for different subsystems. Use Value: Enables adaptive power management; 0.8V start-up allows full functionality even after deep discharge; REF pin supplies accurate voltage to ADC for battery gauge. |
Use Scenario: Portable ECG monitors using disposable 3V lithium batteries, needing clean 5.0V for analog front-end amplifiers and 3.3V for digital signal processor. IC Role / Device Role / Timing Role: Dual-output-capable boost controller (via external feedback configuration) delivering low-noise, low-ripple power with tight regulation across –40°C to +85°C. Use Value: ±1.5% reference tolerance ensures consistent gain calibration; low EMI PFM operation avoids interference with sensitive analog acquisition paths. |
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 |
|---|---|---|---|
| MAX857ESA | 500mA peak switch current limit, fixed 3.3V/5V output (3/5 pin), no FB pin | Better suited for higher-current loads (>100mA) where output voltage is static | Select MAX857ESA when fixed output and higher current capability outweigh need for adjustability. |
| TPS61200DRCT | 20V max input, 0.3V start-up, integrated 1.5A switch, 1.2MHz fixed-frequency PWM | Higher power density and faster transient response, but higher quiescent current (55µA) | Choose TPS61200DRCT for space-constrained designs needing >125mA output or wider input range. |
Compared with MAX859ESA, MAX857ESA offers higher output current but lacks adjustability and low-battery detection; TPS61200DRCT delivers greater integration and speed but trades off ultra-low quiescent current and PFM efficiency at light loads - making MAX859ESA optimal for long-life, low-power, adjustable-rail medical and portable instrumentation.
Availability
MAX859ESA is available at Aetrix Electronics and suitable for glucose meters, portable data-collection equipment, personal data communicators/computers, and medical instrumentation requiring stable component supply across extended temperature ranges and long production lifecycles.
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) is a semiconductor company specializing in high-performance analog, mixed-signal, and power-management ICs for industrial, medical, and consumer applications.
The MAX856–MAX859 family was designed specifically for ultra-low-power, battery-operated systems requiring efficient step-up conversion from sub-1V inputs - targeting portable medical devices, handheld instruments, and energy-constrained IoT endpoints.
FAQ
What is the minimum input voltage required to start up the MAX859ESA?
The MAX859ESA has a typical start-up supply voltage of 0.8V, allowing it to begin operation from nearly depleted single-cell alkaline or NiMH batteries. This value is confirmed across load conditions up to 25mA and is guaranteed over the full –40°C to +85°C operating range. The actual start-up voltage increases slightly with load - e.g., ~0.95V at 25mA - as shown in Figure MAX856-07 of the datasheet. MAX859ESA achieves this via its low-threshold N-channel sense-FET and optimized PFM control architecture.
How does the MAX859ESA achieve ultra-low quiescent current?
The MAX859ESA achieves 25µA typical quiescent current through a combination of CMOS process optimization, current-limited PFM control (eliminating oscillator leakage), and intelligent biasing that scales internal currents with load. In shutdown mode, it draws only 1µA - verified across input voltages from 0.8V to 6.0V and temperatures from –40°C to +85°C. This behavior is intrinsic to the MAX859ESA's architecture and is not dependent on external components or layout.
Can the MAX859ESA be used with a fixed 3.3V or 5V output without external resistors?
No - the MAX859ESA is exclusively an adjustable-output variant and requires an external resistor divider connected between OUT and GND, with the midpoint feeding the FB pin. Fixed-output versions are the MAX856 (3.3V/5V selectable) and MAX858 (3.3V/5V selectable). The MAX859ESA's FB pin replaces the 3/5 select pin found on those parts, and no internal fixed-output option exists. Attempting to tie FB to GND or OUT will result in undefined or non-regulated output voltage.
What is the role of the REF pin on the MAX859ESA, and how should it be bypassed?
The REF pin on the MAX859ESA provides a precision 1.25V reference with ±1.5% tolerance over temperature, capable of sourcing up to 250µA or sinking 20µA. It is intended for external use - e.g., ADC reference or feedback network biasing. When driving an external load, it must be bypassed with a 0.22µF capacitor to GND; if unloaded, ≥0.1µF suffices. This bypass stabilizes the reference under dynamic loading and is explicitly required in the MAX859ESA's design procedure to maintain regulation accuracy.
Does the MAX859ESA include built-in low-battery detection, and how is it configured?
Yes - the MAX859ESA integrates a dedicated low-battery comparator with LBI (input) and LBO (open-drain output) pins. LBI compares applied voltage against the internal 1.25V reference; when voltage drops below threshold, LBO sinks current to GND. Configuration uses a resistor divider from VIN to GND, sized per VLBI = 1.25V × (1 + R3/R4). LBO requires an external pull-up (≥10kΩ to OUT) for logic-level signaling. This function is fully operational across the MAX859ESA's –40°C to +85°C range and adds no significant quiescent overhead.
MAX859ESA Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Series:
- -
- Package/Case:
- 8-SOIC (0.154", 3.90mm Width)
- Packaging:
- Bulk
- Product Status:
- Active
- Applications:
- Converter, Battery Powered Devices
- Voltage - Input:
- 0.8V ~ 6V
- Number of Outputs:
- 1
- Voltage - Output:
- 2.7V ~ 6V
- Operating Temperature:
- -40°C ~ 85°C
- 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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