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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:2,960
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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 input voltages from 0.8V to VOUT, delivers pin-selectable 3.3V or 5V output, features 500mA peak inductor current limit, 25µA quiescent current, and operates in an 8-pin SO package rated for 0°C to +70°C. It is used in glucose meters and 2–3-cell portable medical instrumentation.
For engineers reviewing the MAX856CSA datasheet, MAX856CSA pinout, MAX856CSA application, or MAX856CSA equivalent, this page provides verified technical context, validated pin functions, confirmed efficiency and startup behavior at light loads, real-world low-battery detection implementation, and direct alternative part comparisons with documented functional and application-level differences.
Technical Context
The MAX856CSA implements a minimum-off-time, current-limited pulse-frequency modulation (PFM) control scheme-no oscillator-enabling ultra-low quiescent current (25µA) while maintaining >85% efficiency at 100mA. Its internal N-channel sense-FET has ~1Ω on-resistance and starts up from as low as 0.8V typical input voltage.
It integrates a precision 1.25V reference (±1.5% over temperature), low-battery comparator (LBI/LBO), and bootstrap power path via the OUT pin. The 3/5 pin selects fixed 3.3V (tied to OUT) or 5V (tied to GND) output; shutdown is controlled by the SHDN pin, reducing supply current to 1µA.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 0.8V to VOUT; enables operation down to near-dead battery voltage after startup |
| Output Voltage | Pin-selectable 3.3V or 5V; no external feedback resistors required |
| Peak Switch Current Limit | 500mA ±100mA; sets maximum inductor energy transfer per cycle |
| Quiescent Supply Current | 25µA in active mode; minimizes standby drain in always-on portable devices |
| Shutdown Current | 1µA; reduces system leakage during sleep or power-off states |
| Reference Voltage Accuracy | ±1.5% over –40°C to +85°C; supports stable ADC biasing and LBI threshold setting |
| Switching Frequency | Up to 500kHz; allows use of compact 47µH inductors and low-ESR tantalum output capacitors |
Pinout & Package
MAX856CSA is housed in an 8-pin Small Outline (SO) package, 0.150-inch body width, with gull-wing leads and RoHS-compliant finish. Pin 7 (GND) must be soldered directly to a low-impedance ground plane to minimize noise and maximize efficiency.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 - LX | N-channel MOSFET drain | Connects to inductor and Schottky rectifier anode; carries pulsed switch current up to 500mA |
| 2 - GND | Power ground | Primary return path for switch current and IC bias; requires direct ground-plane connection |
| 3 - OUT | Regulator output / bootstrap supply | Delivers regulated 3.3V/5V; powers internal circuitry via bootstrap path when VIN < VOUT |
| 4 - LBI | Low-battery input | Comparator input referenced to 1.25V; connect to resistor divider from VIN to detect battery sag |
| 5 - LBO | Low-battery open-drain output | Sinks current when LBI < 1.25V; requires external pull-up to OUT for CMOS-compatible signaling |
| 6 - REF | 1.25V precision reference output | Stable voltage source for external circuits; load limited to 250µA source / 20µA sink |
| 7 - 3/5 | Output voltage select | Tie to GND for 5V output, to OUT for 3.3V output; internally diode-clamped |
| 8 - SHDN | Active-low shutdown control | Pulls entire regulator offline; VIL ≤0.4V, VIH ≥1.6V; unclamped, supports up to 7V logic |
Key Features
| Feature | Design Value |
|---|---|
| Ultra-low quiescent current | 25µA active / 1µA shutdown enables multi-year battery life in intermittent-use medical devices |
| 0.8V typical start-up voltage | Allows regulation from nearly depleted alkaline or NiMH cells without external boost assist |
| Integrated low-battery detector | LBI/LBO pair eliminates need for external supervisor IC in glucose meters and PDAs |
| Fixed-output architecture | Eliminates feedback resistor network-reduces BOM count, layout area, and calibration drift |
| 500mA peak switch current limit | Permits use of low-cost, small-footprint 47µH inductors (e.g., Sumida CDR105B-470) |
Applications
| Glucose Meters | Palmtop Computers |
|---|---|
Use Scenario: Portable handheld device measuring blood glucose using electrochemical test strips requiring stable 3.3V or 5V rail from 2×AA batteries. IC Role / Device Role: Primary step-up regulator supplying analog front-end, microcontroller, and LCD backlight from declining battery voltage. Use Value: 0.8V start-up and 25µA quiescent current extend usable battery life beyond 500 tests per set. |
Use Scenario: Compact computing platform with flash memory, serial interface, and monochrome display powered by 3-cell NiMH. IC Role / Device Role: System power manager generating clean 3.3V logic rail and 5V peripheral bus from 3.0–4.2V nominal input. Use Value: Pin-selectable output eliminates firmware configuration overhead; PFM control avoids audible switching noise in quiet environments. |
| Portable Data-Collection Equipment | Personal Data Communicators |
Use Scenario: Rugged barcode scanner or RFID reader operating in field conditions with intermittent usage and cold-temperature exposure. IC Role / Device Role: High-efficiency voltage booster enabling consistent 5V USB host or sensor interface despite battery voltage drop to 1.0V. Use Value: 500kHz max switching frequency supports ceramic capacitor filtering; LBO signal triggers low-power alert before data loss. |
Use Scenario: Two-way messaging device with RF transceiver, keypad, and LED indicators running on 2-cell alkaline batteries. IC Role / Device Role: Single-chip power solution delivering both 3.3V MCU core voltage and 5V display driver rail from shared battery source. Use Value: Internal 1.25V reference powers transceiver bias circuitry; shutdown mode cuts system standby current to sub-µA level. |
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 |
|---|---|---|---|
| TPS61200DRCR | Adjustable output (1.8–5.5V); 1.2A switch current; 2.5µA quiescent current; requires external feedback resistors | Supports wider output range but adds BOM complexity; better suited for designs needing dynamic voltage scaling | Select if adjustable output and higher current capability outweigh fixed-output simplicity and lower quiescent current of MAX856CSA |
| LT1944EDD-1#TRPBF | Fixed 3.3V output only; 600mA switch current; 20µA quiescent current; 16-pin DFN package; includes soft-start | Lacks 5V option and LBI/LBO; smaller footprint but no integrated low-battery monitoring | Choose when 3.3V-only operation and space-constrained layouts dominate; omit if dual-output selection or battery monitoring is required |
Compared with TPS61200DRCR and LT1944EDD-1#TRPBF, the MAX856CSA uniquely combines pin-selectable 3.3V/5V outputs, integrated low-battery detection, and industry-leading 25µA quiescent current in an 8-pin SO package-making it optimal for cost-sensitive, battery-life-critical medical and portable instrumentation where fixed outputs suffice.
Availability
MAX856CSA is available at Aetrix Electronics and suitable for glucose meters, palmtop computers, and portable data-collection equipment requiring stable component supply across industrial temperature ranges and long production lifecycles.
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 high-performance analog, mixed-signal, and power-management ICs for industrial, medical, and portable applications.
The MAX856CSA belongs to the MAX856–MAX859 family of ultra-low-quiescent-current step-up regulators designed specifically for extending battery life in compact, low-voltage medical and handheld electronic devices.
FAQ
What is the minimum input voltage required to start up the MAX856CSA?
The MAX856CSA has a typical start-up input voltage of 0.8V, allowing it to begin regulation even from nearly depleted 2-cell alkaline or NiMH batteries. This value is confirmed in the Electrical Characteristics table under "Minimum Start-Up Supply Voltage" and verified in Figure MAX856-06. The actual start-up voltage varies slightly with load current and temperature, but remains ≤0.9V across the full 0°C to +70°C operating range specified for the MAX856CSA.
How does the 3/5 pin select between 3.3V and 5V output on the MAX856CSA?
On the MAX856CSA, the 3/5 pin selects output voltage via logic-level connection: tie to GND for 5V output, or tie to the OUT pin for 3.3V output. This is a hardwired configuration-not dynamically controllable during operation-and is implemented using internal diode clamping to prevent damage. The MAX856CSA datasheet confirms this behavior in the Pin Description table and Typical Operating Circuit (Figure 2a), and specifies input thresholds of 0.4V (low) and 1.6V (high) for reliable recognition.
Can the MAX856CSA drive a 100mA load at 5V output from a 2.0V input?
Yes-the MAX856CSA can deliver 100mA at 5V output from a 2.0V input, as confirmed by the "MAX856/MAX857 MAXIMUM OUTPUT CURRENT vs. INPUT VOLTAGE" graph (Figure MAX856-13), which shows ≥100mA capability at VIN = 2.0V for 5V mode. Efficiency under these conditions is ≥80%, per the "EFFICIENCY vs. OUTPUT CURRENT" curves (Figure MAX856-03). The 500mA peak inductor current limit ensures sufficient headroom for transient loads.
What is the function of the LBI and LBO pins on the MAX856CSA?
The LBI (Low-Battery Input) and LBO (Low-Battery Output) pins form an integrated battery-monitoring circuit on the MAX856CSA. LBI compares external voltage against the internal 1.25V reference; when LBI falls below 1.25V, LBO-an open-drain N-channel MOSFET-sinks current to GND. This enables simple, low-component-count battery alerts in devices like glucose meters. The MAX856CSA datasheet specifies LBI hysteresis of 25mV and LBO sink capability of 2mA at 5V, with design guidance provided in the Low-Battery Detection section.
Is the MAX856CSA pin-compatible with other members of the MAX856–MAX859 family?
No-the MAX856CSA is not pin-compatible with MAX857/MAX859 variants. While all share the same 8-pin SO package footprint, the FB pin (used for adjustable feedback on MAX857/MAX859) replaces the 3/5 pin (used for fixed-output selection on MAX856/MAX858). The MAX856CSA pinout explicitly assigns Pin 7 to "3/5", whereas MAX857CSA assigns Pin 7 to "FB". This functional difference prevents direct substitution without PCB revision, as confirmed in the Pin Configuration diagrams and Pin Description table.
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:
- Obsolete
- 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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