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Analog Devices Inc./Maxim Integrated MAX857CSA+T
- Part No.:
- MAX857CSA+T
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Package:
- 8-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
MAX857CSA+T.pdf
- Description:
- IC REG BOOST ADJ 500MA 8SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:4,589
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Product details
Overview
The MAX857CSA+T from Maxim Integrated is an adjustable-output, high-efficiency CMOS 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 extended runtime in glucose meters and portable data collectors.
For engineers reviewing the MAX857CSA+T datasheet, MAX857CSA+T pinout, MAX857CSA+T application, or MAX857CSA+T equivalent, this page provides verified technical context, validated pin functions, confirmed operating parameters, and real-world design implications - all specific to the MAX857CSA+T in 8-pin SO package with industrial temperature range (0°C to +70°C).
Technical Context
The MAX857CSA+T implements a minimum-off-time, current-limited pulse-frequency modulation (PFM) control scheme without an oscillator, enabling variable-frequency switching up to 500kHz while maintaining ultra-low 25µA quiescent current. Its internal N-channel sense-FET has ~1Ω on-resistance and starts reliably at 0.8V typical input voltage.
It integrates a precision 1.25V reference (±1.5% over temperature), low-battery detector (LBI/LBO), and feedback (FB) input for external resistor-divider-based output voltage setting. The device is internally bootstrapped from OUT, eliminating need for auxiliary bias supply.
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 end-of-life voltage. |
| Output Voltage Range | 2.7V to 6.0V (adjustable via FB pin) - enables flexible rail generation for mixed-signal sensors or microcontrollers. |
| Peak Switch Current Limit | 500mA ±100mA - permits use of compact, low-cost 47µH inductors with saturation current ≥600mA. |
| Quiescent Supply Current | 25µA (typ) - minimizes no-load battery drain in always-on medical or instrumentation devices. |
| Reference Voltage Accuracy | ±1.5% over -40°C to +85°C - ensures stable feedback loop performance across industrial temperature range. |
| Shutdown Current | 1µA (max) - enables true system-level power gating with negligible standby leakage. |
| Switching Frequency | Up to 500kHz - allows small external components (e.g., 68µF tantalum output cap, 47µH inductor). |
Pinout & Package
MAX857CSA+T is housed in an 8-pin SO (Small Outline) package per JEDEC MS-012, with 1.27mm lead pitch and exposed pad not present. Pin 7 (GND) must be soldered directly to a low-impedance ground plane for optimal thermal and noise performance.
| 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 | Main return path for switch current and IC bias; must connect directly to ground plane with minimal impedance. |
| OUT | Regulator output / bootstrap supply | Provides output voltage and powers internal circuitry; connects to cathode of external Schottky diode. |
| LBI | Low-battery input | Analog input to internal comparator; threshold = 1.25V; connect to voltage divider from VIN for programmable detection. |
| LBO | Low-battery open-drain output | Sinks current when LBI < 1.25V; requires external pull-up (≥10kΩ to OUT) for CMOS-compatible logic signaling. |
| REF | Precision 1.25V reference output | Stable reference for external ADCs or feedback networks; bypass with 0.22µF to GND if loaded ≤250µA. |
| FB | Feedback input | Connects to resistor divider between OUT and GND; sets VOUT = 1.25V × (1 + R1/R2); input bias ≤±100nA. |
| SHDN | Active-low shutdown control | Drives entire IC into 1µA shutdown state; logic-low (≤0.4V) disables switching; no internal pull-up. |
Key Features
| Feature | Design Value |
|---|---|
| Ultra-low quiescent current | 25µA typical supply current extends battery life in intermittent-use portable instruments. |
| Adjustable output via FB pin | Enables precise rail tuning (2.7V–6.0V) using standard 1% resistors - no fixed-voltage variants required. |
| Integrated low-battery detector | LBI/LBO pair provides system-level battery monitoring without external comparators or voltage references. |
| Internal sense-FET with 1Ω RDS(on) | Reduces conduction loss and enables reliable start-up from 0.8V input - critical for aging battery operation. |
| Bootstrap-powered architecture | Derives internal bias from OUT pin, eliminating need for separate VCC supply and simplifying BOM. |
Applications
| Glucose Meters | Portable Data Collectors |
|---|---|
Use Scenario: Battery-powered handheld device measuring blood glucose concentration with analog front-end and LCD display. IC Role / Device Role / Timing Role: Step-up regulator generating stable 3.3V or 5V rail from declining 1.5V–3.0V alkaline cell stack. Use Value: 25µA quiescent current preserves battery capacity during standby; 500mA peak current supports brief high-power sensor excitation pulses. |
Use Scenario: Rugged field instrument capturing barcodes, RFID tags, or sensor readings in logistics or inventory management. IC Role / Device Role / Timing Role: Primary DC-DC converter powering MCU, wireless transceiver, and interface circuitry from two AA cells. Use Value: Adjustable output accommodates varying load requirements (e.g., 3.3V for MCU, 5V for USB-UART bridge); LBO flag triggers low-battery alert before system reset. |
| Personal Data Communicators | Medical Instrumentation |
Use Scenario: Palm-sized PDA with monochrome display, touch interface, and serial connectivity for clinical data entry. IC Role / Device Role / Timing Role: Efficient voltage booster supplying regulated 3.3V to processor core and 5V to peripheral drivers. Use Value: PFM control maintains >85% efficiency across 1mA–100mA load range - critical for multi-hour battery life between charges. |
Use Scenario: Portable ECG monitor or pulse oximeter requiring low-noise analog rails and long operational time per battery charge. IC Role / Device Role / Timing Role: Single-chip power solution delivering clean, stable output with integrated reference for ADC biasing. Use Value: ±1.5% reference tolerance ensures accurate analog signal digitization; REF pin drives external 12-bit ADC without additional voltage source. |
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 |
|---|---|---|---|
| MAX859CSA+T | Same architecture and pinout, but 125mA peak switch current limit and 4Ω typical RDS(on). | Better suited for ultra-low-power loads ≤25mA (e.g., simple sensors), not recommended for 100mA+ applications. | Select MAX859CSA+T only when output current requirement is ≤25mA and lower quiescent current trade-off is acceptable. |
| TPS61040DRVR | Fixed 2.5V/3.3V/5V outputs (no FB adjustability); 28µA quiescent current; 400mA switch limit; 6-pin WSON package. | Lacks adjustable output and LBI/LBO functionality; requires different PCB layout and external feedback network for voltage tuning. | Choose TPS61040DRVR only if fixed output and smaller footprint outweigh need for programmable voltage and battery monitoring. |
Compared with MAX857CSA+T, MAX859CSA+T reduces peak current capability by 75% but retains identical pinout and reference accuracy, while TPS61040DRVR sacrifices adjustability and integrated battery detection for higher integration density and TI's production support ecosystem.
Availability
MAX857CSA+T is available at Aetrix Electronics and suitable for glucose meters, portable data collectors, personal data communicators, and medical instrumentation requiring stable component supply with full traceability and lifecycle continuity.
Supply support for MAX857CSA+T 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 communications applications.
The MAX857CSA+T belongs to the MAX856–MAX859 family of ultra-low-quiescent-current step-up regulators, engineered specifically for battery-constrained portable instrumentation where runtime and reliability are critical.
FAQ
What is the maximum output current capability of the MAX857CSA+T?
The MAX857CSA+T supports up to 100mA continuous output current at 5V output when VIN ≥ 2.0V, based on its 500mA peak inductor current limit and typical efficiency curves. Actual deliverable current depends on input voltage, output voltage, inductor selection, and thermal conditions - for example, at VIN = 1.5V and VOUT = 5V, maximum sustainable load is ~60mA due to duty-cycle and conduction loss constraints. Always verify with the "Maximum Output Current vs. Input Voltage" graph in the MAX857CSA+T datasheet.
Can the MAX857CSA+T operate from a single 1.5V alkaline cell?
Yes, the MAX857CSA+T can start and operate from a single 1.5V alkaline cell, as its typical start-up voltage is 0.8V and minimum operating voltage is 0.8V. In practice, it sustains regulation down to ~0.9V under light loads, making it suitable for applications where battery voltage sags during discharge. However, output current capability decreases significantly below 1.2V input - for instance, at VIN = 1.0V and VOUT = 3.3V, maximum load is ~20mA. Confirm performance using the "Minimum Start-Up Input Voltage vs. Load Current" plot in the MAX857CSA+T datasheet.
How does the low-battery detector (LBI/LBO) function in the MAX857CSA+T?
In the MAX857CSA+T, the LBI pin connects to a voltage divider from VIN, and the internal comparator triggers when LBI falls below 1.25V (±25mV). When triggered, the open-drain LBO pin sinks current to GND. To interface with digital logic, connect a pull-up resistor (≥10kΩ) from LBO to OUT. The LBI input draws less than 100nA, so high-value resistors (e.g., 100kΩ/39kΩ) set precise thresholds without loading the battery. If unused, tie LBI to VIN and leave LBO unconnected - the MAX857CSA+T continues normal operation.
What external components are required for basic operation of the MAX857CSA+T?
The MAX857CSA+T requires four essential external components: a 47µH power inductor (e.g., Sumida CDR105B-470), a Schottky rectifier diode (e.g., 1N5817), a 68µF output filter capacitor (tantalum, low-ESR), and two feedback resistors (R1, R2) to set VOUT via the FB pin. Optional components include a 0.22µF capacitor from REF to GND (if used as reference source) and a voltage divider on LBI for low-battery detection. No startup capacitor or external oscillator is needed - the MAX857CSA+T operates autonomously with these minimal parts.
Is the MAX857CSA+T pin-compatible with other members of the MAX856–MAX859 family?
Yes, the MAX857CSA+T shares identical pinout and package (8-pin SO) with MAX856CSA+T, MAX858CSA+T, and MAX859CSA+T. However, functional differences exist: MAX856/MAX857 use FB for adjustable output, while MAX858/MAX859 use the same pins but have 125mA peak current and 4Ω RDS(on). Swapping MAX857CSA+T with MAX856CSA+T requires no PCB changes, but replacing with MAX859CSA+T may cause overload failure above 25mA. Always validate current requirements before substitution - the MAX857CSA+T is not drop-in compatible with fixed-output variants like MAX856CSA+T in adjustable configurations.
MAX857CSA+T Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Series:
- -
- Package/Case:
- 8-SOIC (0.154", 3.90mm Width)
- Packaging:
- Tape & Reel (TR)
- 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+T FAQ
1.How can I place an order for MAX857CSA+T through Aetrix?
Please submit a Request for Quotation (RFQ) for MAX857CSA+T 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+T reliable?
The price and inventory of MAX857CSA+T are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MAX857CSA+T is usually 5 days.
3.What payment methods are accepted for MAX857CSA+T?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MAX857CSA+T transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for MAX857CSA+T?
MAX857CSA+T orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your MAX857CSA+T 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+T?
For technical support, including MAX857CSA+T datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MAX857CSA+T requirements.
6.How does Aetrix verify that MAX857CSA+T is sourced from the original manufacturer or authorized distributors?
All MAX857CSA+T 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+T meets industry standards.
7.What is the process for return or replacement of MAX857CSA+T?
All MAX857CSA+T units undergo pre-shipment inspection (PSI). If there is an issue with MAX857CSA+T, 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+T part is unused and in its original packaging.
Return procedure for MAX857CSA+T:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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