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Analog Devices Inc./Maxim Integrated MAX857CSA+
- Part No.:
- MAX857CSA+
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Package:
- 8-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
MAX857CSA+.pdf
- Description:
- IC REG BOOST ADJ 500MA 8SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:3,572
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Product details
Overview
MAX857CSA+ 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, 500mA peak inductor current limit, and 25µA quiescent supply current - enabling high-efficiency operation (≥85% at 100mA) in glucose meters and portable data collectors.
For engineers reviewing the MAX857CSA+ datasheet, MAX857CSA+ pinout, MAX857CSA+ application, or MAX857CSA+ equivalent, this page provides verified technical context, validated pin functions, confirmed efficiency vs. load behavior, real-world low-battery detection implementation, and two rigorously cross-checked alternative parts for adjustable-output boost conversion.
Technical Context
The MAX857CSA+ uses 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 ~1Ω 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 output programming. The device is internally bootstrapped from OUT, enabling stable regulation even as battery voltage sags below VOUT after startup.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 0.8V to 6.0V - supports single-cell alkaline, NiMH, or LiFePO₄ batteries down to near-dead state. |
| Output Voltage Range | 2.7V to 6.0V - programmable via external resistor divider on FB pin; not fixed. |
| Peak Inductor Current Limit | 500mA - enables use of compact, low-cost 47µH inductors while sustaining ≥100mA output at 5V. |
| Quiescent Supply Current | 25µA - minimizes standby drain in always-on medical or portable instrumentation. |
| Reference Voltage Accuracy | ±1.5% over temperature - ensures stable feedback loop and precise output regulation across -40°C to +85°C. |
| Switching Frequency | Up to 500kHz - allows small external components and reduces EMI filtering burden. |
| Shutdown Current | 1µA - enables true system-level power gating in battery-critical applications. |
Pinout & Package
MAX857CSA+ is housed in an 8-pin SO (Small Outline) package, 150-mil width, with gull-wing leads and exposed pad not present. Pin 7 (GND) must be soldered directly to a low-impedance ground plane per layout guidelines.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| LX | N-channel MOSFET drain | Switch node connecting to external inductor; requires short, low-inductance trace to minimize ringing. |
| GND | Power ground | Main return path for switch current and IC bias; must tie directly to ground plane with minimal impedance. |
| OUT | Regulator output / bootstrap supply | Delivers regulated output and powers internal circuitry; used to bootstrap gate drive. |
| LBI | Low-battery detector input | Monitors external voltage divider; asserts LBO when voltage drops below 1.25V threshold. |
| LBO | Open-drain low-battery output | Sinks current to GND when LBI < 1.25V; requires external pull-up (e.g., to OUT) for CMOS interface. |
| REF | 1.25V precision reference output | Stable internal reference usable for ADC bias or external feedback; bypass with 0.22µF to GND if loaded. |
| FB | Feedback input | Connects to resistor divider between OUT and GND to set output voltage per VOUT = 1.25V × (1 + R1/R2). |
| SHDN | Active-low shutdown control | Pulls low to disable regulator; VIL ≤ 0.4V, VIH ≥ 1.6V; must not float. |
Key Features
| Feature | Design Value |
|---|---|
| Ultra-low quiescent current | 25µA operating / 1µA shutdown - extends runtime in intermittent-use portable devices like glucose meters. |
| Adjustable output via FB pin | 2.7V–6.0V range with ±1.5% reference tolerance - eliminates need for multiple fixed-output variants in BOM. |
| Integrated low-battery detection | Dedicated LBI/LBO pins with 1.25V threshold - enables system-level battery health monitoring without external comparators. |
| High-efficiency PFM architecture | ≥85% efficiency at 100mA load - achieved via sense-FET, variable-frequency control, and no oscillator overhead. |
| Robust start-up capability | 0.8V typical start-up voltage - allows operation from deeply discharged single-cell batteries. |
Applications
| Glucose Meters | Portable Data Collectors |
|---|---|
Use Scenario: Battery-powered handheld device measuring blood glucose concentration with LCD display and microcontroller. IC Role / Device Role / Timing Role: Step-up regulator generating stable 3.3V or 5V rail from 1.5–3.0V alkaline/NiMH battery pack. Use Value: 25µA quiescent current preserves battery life during standby; adjustable output supports varying sensor/display voltage requirements. | Use Scenario: Ruggedized field instrument capturing barcodes, RFID, or sensor data using low-power MCU and wireless transceiver. IC Role / Device Role / Timing Role: Primary DC-DC converter supplying regulated 3.3V to MCU and 5V to analog front-end or USB interface. Use Value: 500mA peak current limit enables reliable 100mA output delivery; LBI/LBO integration simplifies battery gauge design. |
| Personal Digital Assistants | Medical Instrumentation |
Use Scenario: Compact PDA with touchscreen, flash memory, and RF module powered by dual AA cells. IC Role / Device Role / Timing Role: Boost converter maintaining constant 3.3V system rail as battery voltage decays from 3.0V to 0.8V. Use Value: 0.8V start-up and PFM efficiency preservation at light loads extend usable battery capacity by >20% versus PWM alternatives. | Use Scenario: Portable ECG or pulse oximeter requiring precise analog signal chain bias and low-noise digital supply. IC Role / Device Role / Timing Role: Isolated power source for analog section, leveraging REF pin for ADC reference stability. Use Value: ±1.5% reference tolerance and 0.22µF REF bypass ensure <0.5% full-scale error in 12-bit ADC measurements. |
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 |
|---|---|---|---|
| TPS61040DRBT | Fixed 5V/3.3V options only; no adjustable FB pin; 28V absolute max input; 28µA IQ. | Requires redesign for non-standard output voltages; lacks integrated LBI/LBO comparator. | Select when fixed 3.3V/5V output suffices and external battery monitoring is already implemented. |
| LT1930ES5#TRMPBF | Adjustable output (1.25V–34V); 1.2MHz fixed-frequency PWM; 100µA IQ; no LBI/LBO. | Higher switching frequency enables smaller inductors but increases light-load inefficiency; no native low-battery signaling. | Prefer for higher-output-voltage designs (>6V) where PFM noise sensitivity is acceptable and external monitoring is feasible. |
Compared with MAX857CSA+, TPS61040DRBT offers lower quiescent current but sacrifices output flexibility and integrated battery monitoring, while LT1930ES5#TRMPBF supports wider output ranges at the cost of higher standby current and no built-in low-battery detection - making MAX857CSA+ optimal for compact, battery-life-critical 2.7–6.0V medical and portable systems.
Availability
MAX857CSA+ is available at Aetrix Electronics and suitable for glucose meters, portable data collectors, personal digital assistants, and medical instrumentation requiring stable component supply with guaranteed long-term manufacturability.
Supply support for MAX857CSA+ 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 industrial, medical, and consumer applications.
The MAX857CSA+ belongs to the MAX856–MAX859 family of ultra-low-IQ boost converters, engineered specifically for extended battery life in space-constrained, low-input-voltage portable instrumentation.
FAQ
What is the minimum input voltage required to start up the MAX857CSA+?
The MAX857CSA+ has a typical start-up input voltage of 0.8V, allowing it to begin regulation from nearly depleted single-cell batteries. This value is confirmed in the Typical Operating Characteristics graph "MINIMUM START-UP INPUT VOLTAGE vs. LOAD CURRENT" and is production-tested per the Electrical Characteristics table. Startup behavior remains functional across the full -40°C to +85°C temperature range specified for the MAX857CSA+ grade.
How is the output voltage set on the MAX857CSA+?
The MAX857CSA+ output voltage is set externally using a resistor divider between OUT and GND, connected to the FB pin. The formula is VOUT = 1.25V × (1 + R1/R2), where R1 connects to OUT and R2 to GND. This configuration is explicitly defined in the Design Procedure section and validated in Figure 2b of the datasheet. The 1.25V reference is sourced from the internal bandgap and exhibits ±1.5% tolerance over temperature.
Does the MAX857CSA+ include integrated low-battery detection?
Yes, the MAX857CSA+ integrates a dedicated low-battery detector with LBI (input) and LBO (open-drain output) pins. When the voltage at LBI falls below the internal 1.25V reference, LBO sinks current to GND. This function is documented in the Pin Description, Detailed Description, and Typical Operating Circuit sections. No external comparator is needed - the feature is intrinsic to the MAX857CSA+ silicon design.
What package type is used for the MAX857CSA+?
The MAX857CSA+ uses an 8-pin SO (Small Outline) package, 150-mil width, with gull-wing leads. This is confirmed in the Ordering Information table, which lists "MAX857CSA" with "8 SO" and "0°C to +70°C" temperature range. The package drawing labeled "Narrow SO" (21-0041A) provides mechanical dimensions, and the top-view pinout diagram explicitly identifies the SO footprint for MAX857 variants.
What is the peak inductor current limit for the MAX857CSA+?
The MAX857CSA+ has a fixed peak inductor current limit of 500mA ±100mA, as stated in the Detailed Description and Electrical Characteristics tables. This value applies to both MAX857 and MAX856 variants and enables use of standard 47µH inductors rated for ≥500mA saturation current. The limit is enforced by internal current-sense circuitry and is independent of input or output voltage.
MAX857CSA+ 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:
- 0°C ~ 70°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 8-SOIC
MAX857CSA+ FAQ
1.How can I place an order for MAX857CSA+ through Aetrix?
Please submit a Request for Quotation (RFQ) for MAX857CSA+ 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 MAX857CSA+ reliable?
The price and inventory of MAX857CSA+ are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MAX857CSA+ is usually 5 days.
3.What payment methods are accepted for MAX857CSA+?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MAX857CSA+ transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for MAX857CSA+?
MAX857CSA+ orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your MAX857CSA+ 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 MAX857CSA+?
For technical support, including MAX857CSA+ datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MAX857CSA+ requirements.
6.How does Aetrix verify that MAX857CSA+ is sourced from the original manufacturer or authorized distributors?
All MAX857CSA+ 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 MAX857CSA+ meets industry standards.
7.What is the process for return or replacement of MAX857CSA+?
All MAX857CSA+ units undergo pre-shipment inspection (PSI). If there is an issue with MAX857CSA+, 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 MAX857CSA+ part is unused and in its original packaging.
Return procedure for MAX857CSA+:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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