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Analog Devices Inc./Maxim Integrated MAX850ESA+
- Part No.:
- MAX850ESA+
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Package:
- 8-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
MAX850ESA+.pdf
- Description:
- IC REG CHG PUMP ADJ/-1.28V 8SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:1,275
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Product details
Overview
MAX850ESA+ from Maxim Integrated is a low-noise, inverting, regulated charge-pump DC-DC converter designed to generate a stable -4.1V output at up to 5mA for GaAsFET biasing in cellular transmitter amplifiers. It operates from 4.5V to 10V input, features internal linear regulation reducing output ripple to 2mVp-p, and includes logic-level shutdown with <1µA max current over temperature.
For engineers reviewing the MAX850ESA+ datasheet, MAX850ESA+ pinout, MAX850ESA+ application, or MAX850ESA+ equivalent, this device is selected for precision negative bias generation where low noise, fixed-output stability, and SO-8 thermal performance in -40°C to +85°C industrial environments are critical.
Technical Context
The MAX850ESA+ uses a two-stage architecture: a capacitive charge pump inverts VIN to produce an unregulated negative voltage at NEGOUT, followed by an N-channel pass transistor-based linear regulator that stabilizes and filters the output at OUT. Regulation is achieved via a fixed internal reference (–1.28V) applied to the FB pin when grounded.
It operates at a fixed 100kHz switching frequency, requires no external clock, and delivers load-regulated output with ≤8mV/mA load regulation and ≤3mV/mA line regulation. Shutdown is active-low TTL-compatible on pin 4 (SHDN), disabling both charge pump and regulator while drawing ≤1µA supply current.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Voltage | Fixed –4.1V (±0.2V), set by grounding FB pin - enables plug-and-play GaAsFET VGG bias without external resistors. |
| Output Current | 5mA continuous - sufficient to bias typical GaAsFET power amplifier stages in handheld RF transmitters. |
| Input Voltage Range | 4.5V to 10V - compatible with 4-cell NiCd/NiMH or single Li-ion battery systems with headroom for discharge sag. |
| Output Ripple | 2mVp-p (typical) - achieved via integrated linear post-regulator, critical for minimizing AM noise in RF power stages. |
| Shutdown Current | <1µA max over –40°C to +85°C - ensures negligible battery drain during standby in portable wireless devices. |
| Switching Frequency | 100kHz (fixed) - avoids sensitive IF bands and simplifies EMI filtering compared to variable-frequency alternatives. |
| Operating Temperature | –40°C to +85°C - qualified for industrial and extended-temperature cellular handset operation. |
Pinout & Package
MAX850ESA+ is housed in an 8-pin SO (Small Outline) package, 3.9mm × 4.9mm body, 1.27mm pitch, with exposed pad not connected. Pin 1 is marked by beveled corner or dot; pin numbering follows standard SO convention (counterclockwise from top-left).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 (IN) | Positive power supply input | Accepts 4.5V–10V DC; connects to battery or DC rail - must be decoupled with ≥1µF low-ESR capacitor. |
| 2 (GND) | Circuit ground reference | Common return for all internal blocks; requires low-impedance connection to system ground plane. |
| 3 (NEGOUT) | Unregulated negative charge-pump output | Intermediate node at ~–(VIN + 0.2V); drives C1–/C1+ and feeds linear regulator - not user-accessible. |
| 4 (SHDN) | Active-low shutdown control | Pull ≤0.5V to disable device; high-Z state allows automatic startup - compatible with 3.3V/5V logic outputs. |
| 5 (FB) | Feedback input for output regulation | Grounded to select fixed –4.1V output; open or resistor-connected for adjustable variants (not applicable to MAX850). |
| 6 (OUT) | Regulated negative output | Delivers final –4.1V output; connects directly to GaAsFET gate (VGG) - requires 10µF low-ESR output capacitor (C4). |
| 7 (C1–) | Negative terminal of flying capacitor C1 | Completes charge-pump inversion loop with C1+; must use matched low-ESR ceramic/tantalum (1µF typical). |
| 8 (C1+) | Positive terminal of flying capacitor C1 | Switches between IN and NEGOUT; forms core of voltage-inversion stage - layout symmetry critical for noise. |
Key Features
| Feature | Design Value |
|---|---|
| Fixed –4.1V output | Eliminates external feedback resistors and calibration - reduces BOM count and layout sensitivity in volume RF designs. |
| 2mVp-p output ripple | Enables direct biasing of GaAsFETs without additional LC filtering - preserves signal integrity in narrowband cellular TX paths. |
| 100kHz fixed-frequency operation | Removes need for external clock source or frequency tuning - simplifies design validation and EMI compliance testing. |
| Logic-level active-low SHDN | Allows seamless integration with baseband processor GPIOs - supports fast, deterministic power cycling during transmit/receive gaps. |
| SO-8 industrial temperature grade | Supports deployment in automotive-adjacent and outdoor-rated portable equipment without derating or heatsinking. |
Applications
| Cellular Transmitter Bias | GaAsFET Power Amplifier Modules |
|---|---|
|
Use Scenario: Providing gate bias voltage (VGG) to GaAsFET power amplifiers in GSM/CDMA handset front-ends. IC Role / Device Role / Timing Role: Negative voltage regulator generating precise –4.1V for FET turn-on control and gain stabilization. Use Value: Low 2mVp-p ripple prevents AM-to-AM distortion and adjacent-channel leakage in 900/1800MHz TX chains. |
Use Scenario: Biasing discrete GaAsFETs in portable wireless data loggers requiring low quiescent current. IC Role / Device Role / Timing Role: Standby-capable negative supply enabling microamp-level sleep mode while retaining bias state. Use Value: <1µA shutdown current extends battery life in intermittently transmitting IoT sensor nodes. |
| LCD Contrast Control | Personal Communicator Power Management |
|
Use Scenario: Generating adjustable negative bias for STN/TN LCD segment drivers in handheld PDAs. IC Role / Device Role / Timing Role: Fixed-output charge pump supplying VEE rail - used with external potentiometer for contrast tuning. Use Value: Stable –4.1V output ensures consistent display contrast across battery voltage range (4.5V–10V). |
Use Scenario: Supplying regulated negative bias in dual-mode (voice/data) personal communicators with tight PCB space. IC Role / Device Role / Timing Role: Compact SO-8 solution replacing discrete charge pump + LDO combos in multi-rail PMIC subsystems. Use Value: 8-pin SO footprint minimizes board area versus discrete alternatives while maintaining thermal performance. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar negative charge-pump regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| MAX851ESA+ | Same pinout and specs, but SHDN is active-high - requires inverted control logic or level-shifting. | Preferred where host MCU GPIO defaults high or where synchronous wake-up timing favors active-high assertion. | Select MAX851ESA+ only if system control architecture mandates active-high shutdown signaling. |
| LM2776IDR | Wider input range (2.7V–5.5V), lower max output current (25mA), higher ripple (15mVp-p), different pinout. | Suitable for low-voltage portable devices (e.g., Bluetooth headsets), not for 4-cell or Li-ion powered cellular transmitters. | Choose LM2776IDR only for sub-5.5V systems where higher ripple and non-pin-compatible layout are acceptable. |
Compared with MAX851ESA+, MAX850ESA+ simplifies control interface with active-low SHDN; compared with LM2776IDR, it supports higher input voltage and delivers significantly lower noise - making it the optimal choice for cellular GaAsFET bias where supply stability and RF purity are paramount.
Availability
MAX850ESA+ is available at Aetrix Electronics and suitable for cellular phone RF modules, portable wireless data loggers, and personal communicator power management requiring stable component supply across industrial temperature ranges.
Supply support for MAX850ESA+ 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 U.S.-based semiconductor company specializing in high-performance analog, mixed-signal, and power-management ICs for industrial, communications, and consumer applications.
The MAX850–MAX853 family was engineered specifically for low-noise GaAsFET biasing in battery-powered RF transmitters - prioritizing ripple suppression, shutdown efficiency, and compact integration over general-purpose DC-DC flexibility.
FAQ
What is the exact output voltage tolerance of the MAX850ESA+?
The MAX850ESA+ delivers a nominal –4.1V output with a guaranteed tolerance of ±0.2V over –40°C to +85°C and full load (5mA), as specified in the Electrical Characteristics table under VOUT parameter. This tight tolerance ensures consistent GaAsFET gate biasing across temperature and battery voltage variation, directly supporting repeatable RF power amplifier gain and efficiency.
Can the MAX850ESA+ be used with a 3.7V Li-ion battery?
No - the MAX850ESA+ requires a minimum 4.5V input voltage per its Absolute Maximum Ratings and Electrical Characteristics. A single 3.7V Li-ion cell (nominal) drops below 4.5V during discharge, violating the device's operational specification. Use only with 4-cell alkaline/NiMH (6V) or fully charged Li-ion (≥4.5V) sources, or pair with a boost pre-regulator.
Does the MAX850ESA+ require external feedback resistors to set its output?
No - the MAX850ESA+ has a factory-trimmed internal feedback network that fixes the output at –4.1V when the FB pin (pin 5) is connected to GND. Unlike the MAX852 or MAX853, it does not support adjustable output; no external resistors are needed or recommended for standard operation of the MAX850ESA+.
How does the MAX850ESA+ achieve 2mVp-p output ripple?
The MAX850ESA+ achieves 2mVp-p output ripple through cascaded architecture: a 100kHz charge pump generates the inverted voltage at NEGOUT, then an internal N-channel linear regulator with high PSRR filters and stabilizes the final output at OUT. This dual-stage design suppresses switching artifacts far more effectively than standalone charge pumps, making the MAX850ESA+ suitable for noise-sensitive RF bias rails.
What is the thermal performance of the MAX850ESA+ in SO-8 package at 5mA load?
In its 8-pin SO package, the MAX850ESA+ dissipates approximately 25mW at 5mA output (|–4.1V| × 5mA ≈ 20.5mW plus ~4.5mW quiescent), resulting in negligible junction temperature rise (<2°C) on standard FR-4 with 1oz copper. Its 471mW maximum power dissipation rating at +70°C provides ample margin - no heatsink or airflow is required for typical cellular handset usage.
MAX850ESA+ 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-Down
- Output Configuration:
- Negative
- Topology:
- Charge Pump
- Output Type:
- Adjustable (Fixed)
- Number of Outputs:
- 1
- Voltage - Input (Min):
- 4.5V
- Voltage - Input (Max):
- 10V
- Voltage - Output (Min/Fixed):
- -1.28V (-4.1V)
- Voltage - Output (Max):
- -9V
- Current - Output:
- 5mA
- Frequency - Switching:
- 100kHz
- Synchronous Rectifier:
- No
- Operating Temperature:
- -40°C ~ 85°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 8-SOIC
MAX850ESA+ FAQ
1.How can I place an order for MAX850ESA+ through Aetrix?
Please submit a Request for Quotation (RFQ) for MAX850ESA+ 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 MAX850ESA+ reliable?
The price and inventory of MAX850ESA+ are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MAX850ESA+ is usually 5 days.
3.What payment methods are accepted for MAX850ESA+?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MAX850ESA+ transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for MAX850ESA+?
MAX850ESA+ orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your MAX850ESA+ 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 MAX850ESA+?
For technical support, including MAX850ESA+ datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MAX850ESA+ requirements.
6.How does Aetrix verify that MAX850ESA+ is sourced from the original manufacturer or authorized distributors?
All MAX850ESA+ 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 MAX850ESA+ meets industry standards.
7.What is the process for return or replacement of MAX850ESA+?
All MAX850ESA+ units undergo pre-shipment inspection (PSI). If there is an issue with MAX850ESA+, 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 MAX850ESA+ part is unused and in its original packaging.
Return procedure for MAX850ESA+:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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