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Analog Devices Inc./Maxim Integrated MAX856CSA+
- Part No.:
- MAX856CSA+
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Package:
- 8-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
MAX856CSA+.pdf
- Description:
- IC REG BOOST PROG 500MA 8SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:957
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Product details
Overview
MAX856CSA+ from Maxim Integrated is a high-efficiency, CMOS step-up DC-DC switching regulator optimized for low-input-voltage battery-powered systems. It accepts 0.8V–VOUT input and delivers a pin-selectable 3.3V or 5V output with up to 100mA load capability, 85% typical efficiency at 100mA, 25µA quiescent current, and integrated low-battery detection-used in glucose meters and palmtop computers.
For engineers reviewing the MAX856CSA+ datasheet, MAX856CSA+ pinout, MAX856CSA+ application, or MAX856CSA+ equivalent, this page provides verified technical context, package mapping, real-world operating constraints, and validated alternative options for battery-constrained 3.3V/5V boost conversion.
Technical Context
The MAX856CSA+ employs a minimum-off-time, current-limited pulse-frequency modulation (PFM) control scheme-no oscillator-enabling ultra-low 25µA quiescent current while maintaining >85% efficiency across 2–100mA loads. Its internal 500mA peak switch-current limit and ~1Ω on-resistance support compact 47µH inductor use without external current-sense components.
It integrates a precision 1.25V reference (±1.5% over temperature), open-drain LBO low-battery output with 1.25V threshold, and logic-controlled 3/5 pin for output voltage selection (GND = 5V, OUT = 3.3V). Bootstrapping from OUT enables start-up from 0.8V input and operation down to 0.8V battery sag after startup.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Voltage | PIN-selectable 3.3V or 5V - no external resistors required; simplifies BOM for dual-rail portable designs. |
| Input Voltage Range | 0.8V to VOUT - supports single-cell alkaline/NiMH (0.8V cutoff) and 2-cell Li-ion partial discharge. |
| Peak Switch Current | 500mA ±100mA - sets inductor saturation margin and maximum deliverable output current at given VIN/VOUT. |
| Quiescent Current | 25µA (3.3V mode) - extends battery life in always-on medical sensors and data loggers. |
| Shutdown Current | 1µA - enables deep sleep states in handheld instrumentation with external enable control. |
| Reference Voltage | 1.25V ±1.5% over –40°C to +85°C - stable for external ADC biasing or precision feedback scaling. |
| Switching Frequency | Up to 500kHz - permits small 47µH inductors and reduces EMI filtering footprint vs. lower-frequency boosters. |
Pinout & Package
MAX856CSA+ is housed in an 8-pin SO (Small Outline) package per JEDEC MS-012, 150-mil body width, with GND pin soldered directly to PCB ground plane for thermal and noise performance.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1: SHDN | Active-low shutdown control | Pull low to disable regulator; VIL ≤ 0.4V, VIH ≥ 1.6V - compatible with 3.3V/5V logic without level shift. |
| 2: 3/5 | Output voltage select | Connect to GND for 5V output; connect to OUT for 3.3V output - no external pull-up/down needed. |
| 3: REF | 1.25V precision reference output | Sources up to 250µA; bypass with 0.22µF to GND when loaded - usable as ADC reference or feedback divider bias. |
| 4: LX | Power MOSFET drain node | Switches at up to 500kHz; connects to inductor and Schottky anode - requires short, low-inductance trace. |
| 5: GND | Power ground | Low-impedance return path; must be soldered directly to ground plane - critical for stability and EMI control. |
| 6: OUT | Regulated output & bootstrap supply | Provides power to internal circuitry; feeds external Schottky cathode - defines bootstrapped supply rail. |
| 7: LBI | Low-battery input | Comparator input referenced to 1.25V; connect via resistor divider from battery - enables system-level brownout warning. |
| 8: LBO | Low-battery open-drain output | Sinks current when LBI < 1.25V; requires external pull-up to OUT - drives MCU interrupt or LED indicator. |
Key Features
| Feature | Design Value |
|---|---|
| Ultra-low quiescent current | 25µA in active 3.3V mode - preserves battery capacity during standby in portable medical devices. |
| Integrated low-battery detector | 1.25V threshold with hysteresis (25mV) and open-drain LBO - eliminates need for external supervisor IC in glucose meters. |
| Internal 500mA MOSFET switch | ~1Ω on-resistance - enables full 100mA output at 5V from 2.0V input without external FET or sense resistor. |
| 0.8V start-up capability | Operates from single-cell NiMH/alkaline at end-of-life - extends usable battery range beyond conventional boosters. |
| Pin-selectable fixed output | No feedback resistors required - reduces component count and layout area in space-constrained palmtop PCs. |
Applications
| Glucose Meters | Palmtop Computers |
|---|---|
Use Scenario: Portable blood glucose monitoring with LCD display and microcontroller requiring stable 3.3V/5V rails from two AA batteries. IC Role / Device Role / Timing Role: Primary step-up converter delivering regulated 3.3V to MCU and 5V to LCD backlight driver. Use Value: 25µA quiescent current extends battery life to >6 months in intermittent-use devices; 0.8V start-up ensures operation until battery depletion. |
Use Scenario: Compact handheld computing device powered by 2–3 cell alkaline or NiMH batteries needing dual 3.3V/5V supplies. IC Role / Device Role / Timing Role: System power manager generating main logic voltage (3.3V) and peripheral interface voltage (5V) from shared battery source. Use Value: Pin-selectable outputs eliminate separate regulators; integrated LBO enables automatic low-power mode entry before system reset. |
| Portable Data-Collection Equipment | Medical Instrumentation |
Use Scenario: Handheld barcode scanners or RFID readers operating from replaceable primary cells with strict size and runtime requirements. IC Role / Device Role / Timing Role: High-efficiency boost converter powering 3.3V RF transceiver and 5V sensor interface from 1.8–2.5V input. Use Value: 85% efficiency at 100mA minimizes heat in sealed enclosures; 500mA peak current supports brief high-power transmission bursts. |
Use Scenario: Battery-powered patient monitors with analog front-end, ADC, and wireless telemetry requiring clean, low-noise 3.3V/5V supplies. IC Role / Device Role / Timing Role: Primary DC-DC converter supplying isolated analog and digital domains with precise voltage tracking. Use Value: ±1.5% reference tolerance ensures ADC accuracy; low EMI PFM architecture avoids interference with sensitive analog signal 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 |
|---|---|---|---|
| TPS61200DRCT | Adjustable 1.8–5.5V output; 1.2MHz fixed-frequency PWM; 1.9µA shutdown current; no integrated LBO. | Requires external feedback resistors and low-battery comparator; better suited for higher-frequency, lower-ripple designs. | Select when adjustable output and tighter output ripple control outweigh need for integrated LBO and ultra-low quiescent current. |
| LT1944ES5#TRMPBF | Fixed 3.3V output only; 1.2MHz PWM; 20µA quiescent current; no LBI/LBO; 400mA switch current. | Lacks voltage-select and battery-monitoring features; smaller 5-lead SOT-23 package limits thermal handling. | Select when board space is critical and only 3.3V output is required; verify thermal derating for >60mA continuous loads. |
Compared with TPS61200DRCT and LT1944ES5#TRMPBF, the MAX856CSA+ uniquely combines pin-selectable 3.3V/5V outputs, integrated low-battery detection, and 25µA quiescent current in an SO-8 package-making it optimal for cost-sensitive, battery-life-critical portable medical and data-collection systems where design simplicity and feature integration are prioritized over programmability or ultra-miniaturization.
Availability
MAX856CSA+ is available at Aetrix Electronics and suitable for glucose meters, palmtop computers, and portable data-collection equipment requiring stable component supply with long-term lifecycle assurance and consistent parametric performance.
Supply support for MAX856CSA+ 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 power management, analog, and mixed-signal ICs for industrial, medical, and portable applications.
The MAX856CSA+ belongs to the MAX856–MAX859 family of ultra-low-quiescent-current boost converters designed specifically for battery-powered instrumentation where runtime, start-up voltage, and integration of supervision functions are critical.
FAQ
What is the minimum input voltage required for MAX856CSA+ to start regulation?
The MAX856CSA+ has a typical start-up input voltage of 0.8V, enabling operation from deeply discharged single-cell alkaline or NiMH batteries. This value is load-dependent: at 100mA output, minimum start-up voltage rises to ~0.95V for 3.3V mode and ~1.05V for 5V mode per typical operating characteristics. The MAX856CSA+ sustains regulation down to 0.8V after startup due to bootstrapping from the OUT pin.
How does the 3/5 pin select output voltage on the MAX856CSA+?
On the MAX856CSA+, the 3/5 pin selects output voltage via direct connection: tie to GND for 5V output, tie to OUT for 3.3V output. No external pull-up or pull-down resistors are needed. The pin is internally diode-clamped to GND and OUT, so voltages outside that range must be avoided. This hardware-select method eliminates feedback resistors and ensures deterministic output without configuration firmware.
Does the MAX856CSA+ require an external Schottky diode, and what is its role?
Yes, the MAX856CSA+ requires an external Schottky diode (e.g., 1N5817) connected between LX and OUT. It provides the current path during the MOSFET's off-time, enabling energy transfer from the inductor to the output capacitor. The diode's forward voltage drop directly impacts efficiency and minimum input voltage; Schottky types are mandatory due to their low VF (~0.3V) and fast recovery. PN diodes like 1N4148 reduce efficiency significantly and are not recommended for >20mA loads.
What is the function of the LBI and LBO pins on the MAX856CSA+?
LBI (Low-Battery Input) is a comparator input referenced to the internal 1.25V bandgap. When voltage at LBI falls below 1.25V, the open-drain LBO (Low-Battery Output) sinks current to GND. LBI is typically connected to a resistor divider from the battery; LBO requires an external pull-up (e.g., to OUT) to drive MCU interrupts or LEDs. If unused, LBI must be tied to VIN and LBO left floating - the MAX856CSA+ integrates this supervision function without external components.
Can the MAX856CSA+ operate with input voltage higher than its selected output voltage?
Yes - if the input voltage exceeds the selected output voltage (e.g., VIN = 4.2V with 3.3V output selected), the MAX856CSA+ output follows VIN minus the Schottky diode forward drop (VOUT ≈ VIN − VF). This pass-through behavior is intentional and safe as long as VIN stays within the absolute maximum rating of 7V. However, regulation resumes automatically when VIN drops below VOUT + VF, making the MAX856CSA+ suitable for hybrid battery + wall-adapter systems.
MAX856CSA+ 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:
- Programmable
- Number of Outputs:
- 1
- Voltage - Input (Min):
- 0.8V
- Voltage - Input (Max):
- 6V
- Voltage - Output (Min/Fixed):
- 3.3V, 5V
- Voltage - Output (Max):
- -
- 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
MAX856CSA+ FAQ
1.How can I place an order for MAX856CSA+ through Aetrix?
Please submit a Request for Quotation (RFQ) for MAX856CSA+ 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 MAX856CSA+ reliable?
The price and inventory of MAX856CSA+ are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MAX856CSA+ is usually 5 days.
3.What payment methods are accepted for MAX856CSA+?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MAX856CSA+ transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for MAX856CSA+?
MAX856CSA+ orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your MAX856CSA+ 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 MAX856CSA+?
For technical support, including MAX856CSA+ datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MAX856CSA+ requirements.
6.How does Aetrix verify that MAX856CSA+ is sourced from the original manufacturer or authorized distributors?
All MAX856CSA+ 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 MAX856CSA+ meets industry standards.
7.What is the process for return or replacement of MAX856CSA+?
All MAX856CSA+ units undergo pre-shipment inspection (PSI). If there is an issue with MAX856CSA+, 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 MAX856CSA+ part is unused and in its original packaging.
Return procedure for MAX856CSA+:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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