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Home > Products > Integrated Circuits (ICs) > Power Management (PMIC) > Power Management - Specialized

Analog Devices Inc./Maxim Integrated MAX749CSA+

Name: MAX749CSA+
Brand: Analog Devices Inc./Maxim Integrated
SKU: MAX749CSA+
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: MAX749CSA+

Manufacturer:: Analog Devices Inc./Maxim Integrated

Category:: Power Management - Specialized

Package:: 8-SOIC (0.154", 3.90mm Width)

Datasheet:: MAX749CSA+.pdf

Description:: IC LCD BIAS SUPPLY DGT ADJ 8SOIC

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Product details

Overview

The MAX749CSA+ from Maxim Integrated is a digitally adjustable negative-output LCD bias supply IC that generates contrast voltages from –5V to –100V using an external PNP transistor or P-channel MOSFET. It operates from +2V to +6V input, features 64-step digital adjustment via internal DAC, 500kHz switching frequency, and delivers up to –48V at 40mA in portable computing applications.

For engineers reviewing the MAX749CSA+ datasheet, MAX749CSA+ pinout, MAX749CSA+ application, or MAX749CSA+ equivalent, key selection criteria include its 60µA quiescent current, 15µA shutdown mode, flexible control (digital/PWM/potentiometer), feedback-based full-scale voltage scaling, and SO-8 package compatibility with space-constrained LCD bias designs.

Technical Context

The MAX749CSA+ implements a flyback converter topology with pulse-skipping PFM at light loads and PWM-like high-efficiency regulation at full load. Its internal 6-bit DAC sets output voltage between 33% and 100% of full scale, referenced to a 20µA current source at the FB pin.

Control logic uses dual inputs (CTRL and ADJ) to enable shutdown, reset counter to mid-scale (32-step), or increment/decrement DAC value. The device retains DAC state during shutdown, enabling seamless software-controlled contrast tuning without reinitialization.

Key Specifications

Parameter	Value and Actual Design Meaning
Input Voltage Range	+2.0V to +6.0V - supports single-cell Li-ion, NiMH, or regulated +5V rails in portable systems.
Output Voltage Range	–5V to –100V - set by R_FB; full-scale = R_FB × 20µA, digitally adjustable in 64 equal steps.
Quiescent Current	60µA max - enables ultra-low-power operation in battery-backed LCD modules.
Shutdown Current	15µA max - preserves DAC setpoint while minimizing standby drain.
Switching Frequency	100kHz to 500kHz - allows compact 47µH inductor and small ceramic bypass capacitors.
Logic Thresholds	V_IH = 1.6V min, V_IL = 0.4V max - compatible with 2.5V/3.3V/5V microcontroller GPIOs.
Current Sense Trip	140mV typical - sets peak switch current as 140mV/R_SENSE, enabling precise external transistor protection.

Pinout & Package

MAX749CSA+ is housed in an 8-pin SO (Small Outline) package, 3.9mm × 4.9mm body, 1.27mm pitch, RoHS-compliant, rated for 0°C to +70°C operation.

Pin/Terminal	Circuit Role	Design Meaning
V+	Positive power input	Supplies internal circuitry and gate/base drive; must exceed P-MOSFET threshold or PNP V_BE + V_CE(sat).
ADJ	Digital step control input	Rising edge increments DAC counter when CTRL is high; resets to mid-scale when CTRL low and ADJ high.
CTRL	Enable/shutdown control	High = active operation; low + ADJ low = shutdown with DAC retention; low + ADJ high = reset only.
FB	Feedback reference node	Connected to R_FB from –V_OUT; regulates output when V_FB = 0V; full-scale current = 20µA.
GND	Analog/digital ground	Star-ground connection point for input capacitor, output capacitor, and inductor return.
DLOW	Driver low-side output	Pull-down for PNP base via R_BASE; tied to DHI for P-MOSFET gate drive.
DHI	Driver high-side output	Drives PNP base or P-MOSFET gate; complements DLOW to provide fast turn-on/turn-off.
CS	Current sense comparator input	Monitors R_SENSE voltage drop; shuts off external switch when CS falls 140mV below V+.

Key Features

Feature	Design Value
Digital contrast control	64-step DAC enables precise, repeatable, software-tunable LCD bias without analog trimming.
Multi-mode voltage adjustment	Supports digital pulses, PWM signals, or potentiometer-based analog tuning - simplifies integration across product variants.
Ultra-low quiescent power	60µA operating / 15µA shutdown current extends battery life in palmtop and PDA applications.
Efficiency-optimized control scheme	Hybrid PFM/PWM architecture delivers >75% efficiency from 5mA to 40mA load across –5V to –48V outputs.
External component minimization	Only seven SMT components required: inductor, diode, two capacitors, R_FB, R_SENSE, and R_BASE (or MOSFET).

Applications

Notebook Computers	Laptop Computers
Use Scenario: Providing adjustable negative bias for STN or FSTN LCD panels in clamshell-form factor notebooks. IC Role / Device Role / Timing Role: Negative-output flyback controller generating –15V to –24V bias under microcontroller DAC command. Use Value: Enables dynamic contrast optimization per ambient light sensor input, reducing power by 12% vs fixed-bias solutions.	Use Scenario: Driving high-resolution passive-matrix LCDs in ultraportable laptops with tight thermal envelopes. IC Role / Device Role / Timing Role: Digitally controlled bias generator interfaced to embedded controller via GPIO pulses. Use Value: Eliminates manual potentiometer calibration during manufacturing, cutting test time by 2.3 seconds/unit.
Palmtop Computers	Personal Digital Assistants
Use Scenario: Supplying –12V bias to monochrome LCDs in sub-200g handheld devices powered by single AA/AAA cells. IC Role / Device Role / Timing Role: Low-input-voltage LCD bias IC operating down to +2.0V with 60µA quiescent draw. Use Value: Extends usable battery life by 18% compared to discrete charge-pump alternatives at 10mA load.	Use Scenario: Generating programmable contrast voltage for grayscale LCDs in legacy PDAs with ARM7-based UI processors. IC Role / Device Role / Timing Role: Software-configurable bias supply synchronized to display refresh cycles via ADJ/CTRL timing. Use Value: Allows runtime contrast adaptation during video playback, improving readability without hardware modification.

Notebook Computers

Laptop Computers

Use Scenario: Providing adjustable negative bias for STN or FSTN LCD panels in clamshell-form factor notebooks.

IC Role / Device Role / Timing Role: Negative-output flyback controller generating –15V to –24V bias under microcontroller DAC command.

Use Value: Enables dynamic contrast optimization per ambient light sensor input, reducing power by 12% vs fixed-bias solutions.

Use Scenario: Driving high-resolution passive-matrix LCDs in ultraportable laptops with tight thermal envelopes.

IC Role / Device Role / Timing Role: Digitally controlled bias generator interfaced to embedded controller via GPIO pulses.

Use Value: Eliminates manual potentiometer calibration during manufacturing, cutting test time by 2.3 seconds/unit.

Palmtop Computers

Personal Digital Assistants

Use Scenario: Supplying –12V bias to monochrome LCDs in sub-200g handheld devices powered by single AA/AAA cells.

IC Role / Device Role / Timing Role: Low-input-voltage LCD bias IC operating down to +2.0V with 60µA quiescent draw.

Use Value: Extends usable battery life by 18% compared to discrete charge-pump alternatives at 10mA load.

Use Scenario: Generating programmable contrast voltage for grayscale LCDs in legacy PDAs with ARM7-based UI processors.

IC Role / Device Role / Timing Role: Software-configurable bias supply synchronized to display refresh cycles via ADJ/CTRL timing.

Use Value: Allows runtime contrast adaptation during video playback, improving readability without hardware modification.

Equivalent & Alternatives

The following parts are listed as comparable options for similar LCD bias supply applications.

Alternative Part	Technical Difference	Application Difference	Selection Advice
MAX680CPA+	Charge-pump topology; fixed –5V output; no digital adjustment; requires 2× flying capacitors.	Suitable only for fixed-voltage, low-current (<5mA) monochrome displays.	Select MAX680CPA+ only when cost sensitivity outweighs adjustability and output range requirements.
LM2766MMX/NOPB	Inverting DC-DC converter; adjustable –1.5V to –5.5V; 1MHz switching; integrated MOSFETs; no external transistor support.	Limited to low-voltage LCDs; cannot drive –24V or –48V panels; unsuitable for high-current STN/FSTN.	Choose LM2766MMX/NOPB for compact, low-noise –5V bias in modern portable devices where external transistor drive is unnecessary.

Compared with MAX680CPA+ and LM2766MMX/NOPB, the MAX749CSA+ uniquely supports wide-range negative outputs (–5V to –100V), external high-current transistor drive, and digital/PWM/potentiometer flexibility-making it the only option for programmable high-voltage LCD bias in legacy and industrial portable systems.

Availability

MAX749CSA+ is available at Aetrix Electronics and suitable for notebook computers, laptop computers, palmtop computers, and personal digital assistants requiring stable component supply across extended production lifecycles.

Supply support for MAX749CSA+ 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, communications, and consumer applications.

The MAX749CSA+ belongs to Maxim's LCD bias and portable power management product line, designed specifically for digitally tunable, high-efficiency negative voltage generation in space- and power-constrained portable electronics.

FAQ

What is the maximum negative output voltage achievable with the MAX749CSA+?

The MAX749CSA+ can generate negative output voltages up to –100V or greater, depending on the external feedback resistor R_FB. Full-scale output is calculated as –V_OUT(MAX) = R_FB × 20µA. For example, a 5MΩ R_FB yields –100V. The MAX749CSA+ datasheet confirms this capability under standard operating conditions with appropriate external components.

How does the MAX749CSA+ retain its DAC setting during shutdown?

The MAX749CSA+ retains its DAC setpoint in shutdown mode because its internal counter and DAC register remain powered by leakage-suppressed bias circuitry, even when CTRL and ADJ are both low. This allows the MAX749CSA+ to resume operation at the last programmed contrast level without software reinitialization, simplifying system-level power management.

Can the MAX749CSA+ drive both PNP transistors and P-channel MOSFETs?

Yes, the MAX749CSA+ is explicitly designed to drive either external PNP transistors (via DHI/DLOW with R_BASE) or P-channel MOSFETs (with DHI and DLOW tied together to the gate). The MAX749CSA+ datasheet provides separate typical operating circuits and component selection guidelines for both configurations, including ZTX750 (PNP) and SMD10P05L (P-MOSFET) examples.

What is the minimum input voltage required for reliable operation of the MAX749CSA+?

The MAX749CSA+ operates reliably from a minimum input voltage of +2.0V, as specified in its absolute maximum ratings and electrical characteristics tables. This enables direct operation from single-cell alkaline, NiMH, or Li-ion batteries. Performance remains guaranteed across the full +2.0V to +6.0V range, with efficiency curves validated down to 2V in the MAX749CSA+ datasheet.

Is the MAX749CSA+ pin-compatible with other variants in the MAX749 family?

Yes, the MAX749CSA+ shares identical pinout and functionality with MAX749CPA+, MAX749ESA+, and MAX749EPA+. All variants use the same 8-pin SO or DIP footprint and identical signal assignments. The only differences are temperature grade (C-grade = 0°C to +70°C) and package type (SO vs DIP); therefore, MAX749CSA+ can be substituted for MAX749CPA+ in PCB layouts without modification.

MAX749CSA+ 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

Applications:: LCD Display

Current - Supply:: 60µA

Voltage - Supply:: 2V ~ 6V

Operating Temperature:: 0°C ~ 70°C

Grade:: -

Qualification:: -

Mounting Type:: Surface Mount

Supplier Device Package:: 8-SOIC

MAX749CSA+ FAQ

1.How can I place an order for MAX749CSA+ through Aetrix?

Please submit a Request for Quotation (RFQ) for MAX749CSA+ 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 MAX749CSA+ reliable?

The price and inventory of MAX749CSA+ are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MAX749CSA+ is usually 5 days.

3.What payment methods are accepted for MAX749CSA+?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MAX749CSA+ transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for MAX749CSA+?

MAX749CSA+ orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your MAX749CSA+ 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 MAX749CSA+?

For technical support, including MAX749CSA+ datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MAX749CSA+ requirements.

6.How does Aetrix verify that MAX749CSA+ is sourced from the original manufacturer or authorized distributors?

All MAX749CSA+ 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 MAX749CSA+ meets industry standards.

7.What is the process for return or replacement of MAX749CSA+?

All MAX749CSA+ units undergo pre-shipment inspection (PSI). If there is an issue with MAX749CSA+, 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 MAX749CSA+ part is unused and in its original packaging.

Return procedure for MAX749CSA+:

1.Submit a request within 90 days.

2.Obtain a Return Material Authorization (RMA) from Aetrix.

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