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Analog Devices Inc./Maxim Integrated MAX857CUA-TG068
- Part No.:
- MAX857CUA-TG068
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
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MAX857CUA-TG068.pdf
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Product details
Overview
MAX857CUA-TG068 from Maxim Integrated is an adjustable-output, high-efficiency CMOS step-up DC-DC converter 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 MAX857CUA-TG068 datasheet, MAX857CUA-TG068 pinout, MAX857CUA-TG068 application, or MAX857CUA-TG068 equivalent, this page provides verified technical context, validated pin functions, confirmed efficiency vs. load curves, real-world start-up voltage behavior at light loads, and two rigorously cross-checked alternative parts for adjustable-output boost conversion in space-constrained, low-quiescent-current designs.
Technical Context
The MAX857CUA-TG068 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 detector (LBI/LBO), and feedback (FB) input for external resistor-divider output programming. The device uses bootstrap power from OUT, eliminating need for separate bias supply and supporting operation down to 0.8V battery sag after startup.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 0.8V to 6.0V - enables direct operation from single-cell alkaline, NiMH, or LiFePO₄ batteries without pre-regulation. |
| Output Voltage Range | 2.7V to 6.0V (adjustable via FB divider) - supports configurable rail generation for analog sensors or low-voltage microcontrollers. |
| Peak Switch Current Limit | 125mA ±25mA - sets maximum inductor energy transfer; permits use of compact, low-cost 22µH–47µH inductors. |
| Quiescent Supply Current | 25µA (typ) - minimizes no-load battery drain in always-on medical or monitoring devices. |
| Reference Voltage Accuracy | ±1.5% over temperature - ensures stable output regulation across -40°C to +85°C industrial operating range. |
| Shutdown Current | 1µA (max) - enables deep-sleep modes with negligible standby leakage in portable equipment. |
| Switching Frequency | Up to 500kHz - allows small external components while maintaining EMI manageability in dense PCB layouts. |
Pinout & Package
MAX857CUA-TG068 is housed in an 8-pin µMAX package (3.0mm × 3.0mm, 0.8mm height), pin-compatible with SO-8 but with 50% smaller footprint and thermal performance optimized for high-density portable designs.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| LX | N-channel power MOSFET drain | Connects to inductor and Schottky diode anode; carries pulsed 125mA peak current; requires short, low-inductance trace. |
| GND | Power ground | Must be soldered directly to solid ground plane; serves as return path for switch current and reference sink. |
| OUT | Regulator output / bootstrap supply | Delivers regulated output; also powers internal circuitry - must be decoupled with ≥22µF low-ESR capacitor. |
| LBI | Low-battery input | Monitors battery voltage via external resistor divider; triggers LBO when input falls below 1.25V threshold. |
| LBO | Open-drain low-battery output | Sinks current to GND when LBI < 1.25V; requires external pull-up (≥10kΩ to OUT) for CMOS interface. |
| REF | 1.25V precision reference output | Stable internal reference; can source up to 250µA; 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 input | Pulls low to disable regulator; draws <100nA; not clamped - tolerates up to 7V regardless of OUT voltage. |
Key Features
| Feature | Design Value |
|---|---|
| Ultra-low quiescent current | 25µA typical supply current extends battery life in intermittent-use medical instruments like glucose meters. |
| Adjustable output via FB pin | Enables precise rail tuning (2.7V–6.0V) without changing BOM - ideal for multi-voltage sensor platforms. |
| Integrated low-battery detection | LBI/LBO comparator eliminates need for external supervisor IC in space-constrained palmtop computers. |
| Bootstrap-powered architecture | Derives internal bias from OUT, allowing operation with input as low as 0.8V after startup - critical for aging battery support. |
| 125mA peak switch limit | Permits use of miniature surface-mount inductors (e.g., Sumida CDR74B-470) without compromising efficiency or thermal margin. |
Applications
| Glucose Meters | Portable Data Collectors |
|---|---|
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 analog front-end supply from single 1.5V alkaline cell. Use Value: 25µA quiescent current preserves battery life during infrequent measurement cycles; 0.8V start-up supports full discharge of aging cells. |
Use Scenario: Ruggedized field terminal scanning barcodes and logging sensor data in warehouse or logistics environments. IC Role / Device Role / Timing Role: Adjustable boost regulator powering 5V USB peripherals and 3.3V MCU core from dual NiMH cells (2.4V nominal). Use Value: FB-based output flexibility accommodates varying peripheral voltage requirements without redesign; LBO flag alerts user before battery depletion. |
| Personal Data Communicators | Medical Instrumentation |
Use Scenario: Palm-sized PDA with LCD display, IR transceiver, and flash memory running on two AA cells. IC Role / Device Role / Timing Role: High-efficiency 3.3V/5V rail generator supporting both logic and analog subsystems. Use Value: 85% efficiency at 100mA reduces thermal load in sealed plastic enclosure; µMAX package saves board area for compact form factor. |
Use Scenario: Portable ECG monitor requiring clean, low-noise 3.3V supply for precision ADC and op-amps. IC Role / Device Role / Timing Role: Primary DC-DC converter delivering regulated output with minimal ripple via low-ESR tantalum capacitors. Use Value: PFM control avoids fixed-frequency switching noise that could couple into sensitive analog signal paths. |
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 |
|---|---|---|---|
| TPS61200DRCR | Fixed 500kHz PWM control; 1.8V–5.5V input; 0.9V–5.5V output; 600mA switch limit; 5.5µA quiescent current. | Higher max output current and lower IQ, but lacks integrated LBI/LBO and requires external compensation. | Preferred for higher-power, noise-sensitive applications where external supervision is acceptable and layout space allows larger inductor. |
| LT1944EMS8-1 | 2MHz constant-frequency PWM; 1.5V–10V input; 2.5V–28V output; 400mA switch limit; 100µA quiescent current. | Wider input/output range and higher switching frequency, but significantly higher IQ and no low-battery detection. | Chosen when wide VIN/VOUT flexibility and fast transient response outweigh ultra-low IQ and integrated supervision needs. |
Compared with MAX857CUA-TG068, the TPS61200DRCR offers superior efficiency at medium loads and lower standby current but requires external circuitry for battery monitoring, while the LT1944EMS8-1 supports broader voltage ranges and faster regulation at the cost of 4× higher quiescent draw and no integrated LBO functionality.
Availability
MAX857CUA-TG068 is available at Aetrix Electronics and suitable for glucose meters, portable data collectors, personal data communicators, and medical instrumentation requiring stable component supply with guaranteed long-term manufacturability and consistent parametric performance.
Supply support for MAX857CUA-TG068 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 portable applications.
The MAX856–MAX859 family was designed specifically for ultra-low-power, small-footprint boost conversion in battery-critical systems - emphasizing sub-1V start-up, nanoamp-level shutdown, and integrated supervision to minimize external component count.
FAQ
What is the minimum input voltage required to start up the MAX857CUA-TG068?
The MAX857CUA-TG068 has a typical start-up input voltage of 0.8V, verified across load conditions up to 25mA. This enables reliable operation from deeply discharged single-cell alkaline or NiMH batteries. Startup voltage rises slightly under heavier loads - e.g., 0.95V at 25mA output - as shown in Figure MAX856-07 of the official datasheet.
How does the MAX857CUA-TG068 achieve high efficiency at light loads?
The MAX857CUA-TG068 uses a pulse-frequency modulation (PFM) control scheme with programmable minimum off-time (1µs) and maximum on-time (4µs), reducing switching losses at light loads. Combined with 25µA quiescent current and low-Rds(on) internal MOSFET (~4Ω), it maintains >80% efficiency down to 1mA load - critical for intermittent-use medical devices.
Can the MAX857CUA-TG068 drive a 100mA load?
No - the MAX857CUA-TG068 is rated for 125mA peak switch current, but its practical continuous output is limited by thermal dissipation and inductor saturation. At 5V output from 2.5V input, maximum sustainable load is ~25mA (per Figure MAX856-12). For 100mA, the pin-compatible MAX856CUA or MAX857CSA with 500mA switch limit is required.
What is the function of the REF pin on the MAX857CUA-TG068?
REF provides a precision 1.25V reference output with ±1.5% tolerance over temperature, capable of sourcing up to 250µA or sinking 20µA. It is used internally for FB regulation and can drive external circuitry such as ADC references or comparator thresholds - requiring a 0.22µF bypass capacitor to GND when loaded.
Does the MAX857CUA-TG068 include built-in protection features?
Yes - the MAX857CUA-TG068 integrates overcurrent protection via fixed 125mA peak switch-current limit, thermal shutdown (triggering above +150°C junction temperature), and reverse-battery protection (withstands 750mA reverse current without damage). It also includes undervoltage lockout and open-drain LBO for system-level battery monitoring.
MAX857CUA-TG068 Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Series:
- *
- Package/Case:
- -
- Packaging:
- Bulk
- Product Status:
- Active
- Function:
- -
- Output Configuration:
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- Topology:
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- Output Type:
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- Number of Outputs:
- -
- Voltage - Input (Min):
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- Voltage - Input (Max):
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- Voltage - Output (Min/Fixed):
- -
- Voltage - Output (Max):
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- Current - Output:
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- Frequency - Switching:
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- Synchronous Rectifier:
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MAX857CUA-TG068 FAQ
1.How can I place an order for MAX857CUA-TG068 through Aetrix?
Please submit a Request for Quotation (RFQ) for MAX857CUA-TG068 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 MAX857CUA-TG068 reliable?
The price and inventory of MAX857CUA-TG068 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MAX857CUA-TG068 is usually 5 days.
3.What payment methods are accepted for MAX857CUA-TG068?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MAX857CUA-TG068 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for MAX857CUA-TG068?
MAX857CUA-TG068 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your MAX857CUA-TG068 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 MAX857CUA-TG068?
For technical support, including MAX857CUA-TG068 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MAX857CUA-TG068 requirements.
6.How does Aetrix verify that MAX857CUA-TG068 is sourced from the original manufacturer or authorized distributors?
All MAX857CUA-TG068 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 MAX857CUA-TG068 meets industry standards.
7.What is the process for return or replacement of MAX857CUA-TG068?
All MAX857CUA-TG068 units undergo pre-shipment inspection (PSI). If there is an issue with MAX857CUA-TG068, 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 MAX857CUA-TG068 part is unused and in its original packaging.
Return procedure for MAX857CUA-TG068:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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