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Analog Devices Inc./Maxim Integrated MAX1721EUT-T
- Part No.:
- MAX1721EUT-T
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Package:
- SOT-23-6
- Datasheet:
-
MAX1721EUT-T.pdf
- Description:
- IC REG CHARGE PUMP INV 25MA SOT6
- Quantity:
- Payment:
- Shipping:
Inventory:4,999
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Product details
Overview
The MAX1721EUT-T from Maxim Integrated is a monolithic CMOS switched-capacitor voltage inverter with logic-controlled shutdown, designed to generate a regulated negative output (–VIN) from a +1.5V to +5.5V input supply. It operates at 125kHz, delivers up to 25mA continuous output current, achieves 99.9% voltage conversion efficiency, and uses only two 1µF external ceramic capacitors - ideal for space-constrained analog biasing in portable instrumentation.
For engineers reviewing the MAX1721EUT-T datasheet, MAX1721EUT-T pinout, MAX1721EUT-T application, or MAX1721EUT-T equivalent, key selection criteria include its 125kHz oscillator frequency, 1nA shutdown current, 23Ω typical output resistance at +5V, SOT23-6 package compatibility, and noninverting shutdown polarity (SHDN high = normal operation).
Technical Context
The MAX1721EUT-T implements a four-switch charge-pump topology with integrated power MOSFETs and oscillator control circuitry. Its output voltage follows VOUT ≈ –(VIN – IOUT × RO), where RO is ~23Ω at +5V and 25°C, making it unregulated but highly predictable under load.
Shutdown is noninverting: driving SHDN high enables normal operation; pulling SHDN low forces shutdown, actively pulling OUT to GND via a 4Ω internal switch and reducing supply current to 1nA. Startup wake-up time is 80µs, and output ripple is minimized using low-ESR 1µF ceramic capacitors on C1 and C2.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Oscillator Frequency | 125kHz - determines switching speed, capacitor sizing, and output impedance trade-off. |
| Input Voltage Range | +1.5V to +5.5V - supports single-cell Li-ion, alkaline, and 3.3V/5V logic rails as input sources. |
| Output Current | 25mA continuous - sufficient for op-amp biasing, sensor signal conditioning, and small LCD bias supplies. |
| Voltage Conversion Efficiency | 99.9% (typ.) - minimizes power loss and thermal rise in battery-powered systems. |
| Shutdown Supply Current | 1nA - enables ultra-low-power sleep modes in always-on portable devices. |
| Output Resistance | 23Ω (typ. at VIN = +5V, TA = +25°C) - defines output droop: VDROOP− = IOUT × 23Ω. |
| Quiescent Current | 50µA (typ.) - sets no-load power draw during active operation. |
Pinout & Package
MAX1721EUT-T is housed in a 6-pin SOT23-6 package with exposed pad (not thermally enhanced). Pin 1 is C1+, pin 2 is C1−, pin 3 is IN, pin 4 is SHDN, pin 5 is OUT, and pin 6 is GND - matching the standard SOT23-6 top-mark "AABT" layout.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| C1+ | Positive terminal of flying capacitor | Connects to one side of external 1µF pump capacitor (C1); critical for charge transfer timing. |
| C1− | Negative terminal of flying capacitor | Connects to other side of C1; forms charge-transfer path during second half-cycle. |
| IN | Positive input supply rail | Accepts +1.5V to +5.5V; powers internal oscillator and switches; defines nominal output magnitude. |
| SHDN | Noninverting shutdown control | Logic high = active mode; logic low = shutdown (OUT pulled to GND via 4Ω). |
| OUT | Inverting charge-pump output | Delivers –VIN (e.g., –5V from +5V); output voltage droops linearly with load current. |
| GND | Analog and power ground reference | Common return for IN, OUT, and internal switches; must be low-impedance for noise control. |
Key Features
| Feature | Design Value |
|---|---|
| Logic-controlled shutdown | 1nA quiescent current in shutdown with active GND pull-down on OUT - eliminates need for external discharge path. |
| High-frequency operation | 125kHz switching enables use of compact 1µF ceramic capacitors instead of larger electrolytics or tantalums. |
| Ultra-high conversion efficiency | 99.9% efficiency at light loads reduces thermal stress and extends battery life in portable equipment. |
| Minimal external components | Only two 1µF capacitors required (C1, C2) plus optional bypass C3 - simplifies BOM and PCB layout. |
| Predictable output droop | 23Ω typical output resistance allows precise calculation of VOUT under load: VOUT = –(VIN – IOUT × 23Ω). |
Applications
| Local Negative Supply Generation | Small LCD Panel Bias |
|---|---|
|
Use Scenario: Generating –5V from a +5V microcontroller supply to power op-amps or ADC reference buffers in handheld test equipment. IC Role / Device Role / Timing Role: Voltage inverter providing isolated negative rail without inductors or transformers. Use Value: Enables dual-supply analog circuitry from a single positive rail, using only two 1µF ceramics and zero inductors. |
Use Scenario: Supplying –15V bias to segment electrodes in monochrome STN LCD modules used in medical handhelds. IC Role / Device Role / Timing Role: Charge-pump inverter delivering stable negative voltage at 125kHz switching frequency. Use Value: Eliminates bulky discrete charge-pump ICs; 25mA output supports multi-segment drive with minimal board area. |
| GaAs PA Bias Supply | Battery-Operated Instrumentation |
|
Use Scenario: Providing –3.3V gate bias for GaAs FET power amplifiers in portable RF transceivers operating from 3.3V Li-ion cells. IC Role / Device Role / Timing Role: Low-noise, high-efficiency inverter with fast 80µs wake-up for burst-mode PA control. Use Value: 1nA shutdown current preserves battery capacity during standby; 125kHz operation avoids RF interference bands. |
Use Scenario: Powering precision analog front-ends (e.g., strain gauge amplifiers) in portable data loggers running on two AA cells. IC Role / Device Role / Timing Role: Compact SOT23-6 inverter generating –1.5V from 1.5V–3.0V input range for rail-to-rail op-amp operation. Use Value: Supports operation down to +1.5V input, enabling full functionality across entire battery discharge curve. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar switched-capacitor voltage inverter applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| MAX1720EUT-T | 12kHz oscillator frequency; requires 10µF capacitors; 90µA quiescent current; inverted shutdown logic (SHDN low = active). | Better suited for ultra-low-noise, low-EMI applications where slower switching is acceptable. | Select MAX1720EUT-T when EMI sensitivity outweighs size constraints and 10µF capacitors are acceptable. |
| MAX860ESA+ | Regulated –2×VIN output; µMAX-8 package; 50mA output; no shutdown; higher IQ (120µA). | Used where fixed-ratio negative regulation is required, not just inversion. | Choose MAX860ESA+ only if regulation stability and higher current (>25mA) are mandatory - not a drop-in replacement. |
Compared with MAX1720EUT-T, the MAX1721EUT-T offers 10× faster switching (125kHz vs. 12kHz), enabling 10× smaller capacitors and lower output impedance, while differing in shutdown polarity. Compared with MAX860ESA+, it trades regulation and higher current for ultra-small size, lower IQ, and true inverting (–VIN) behavior - making it optimal for unregulated, space-critical bias generation.
Availability
MAX1721EUT-T is available at Aetrix Electronics and suitable for battery-operated instrumentation, portable LCD biasing, GaAs amplifier gate control, and local analog supply generation requiring stable component supply across industrial temperature ranges (–40°C to +85°C).
Supply support for MAX1721EUT-T 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 MAX1719/MAX1720/MAX1721 family was designed specifically for ultra-compact, high-efficiency switched-capacitor voltage inversion in space- and power-constrained portable electronics - emphasizing minimal external components and nanoscale shutdown current.
FAQ
What is the shutdown logic polarity of the MAX1721EUT-T?
The MAX1721EUT-T features noninverting shutdown control: applying a logic high (≥VIN − 0.2V) to SHDN enables normal operation, while pulling SHDN low (≤0.6V) places the device in shutdown mode, actively pulling OUT to GND through a 4Ω internal switch. This differs from the MAX1719EUT-T, which uses inverted logic.
Can the MAX1721EUT-T generate a regulated –5V output from a +5V input?
No - the MAX1721EUT-T is an unregulated inverter. Its output approximates –VIN (e.g., –5V), but actual VOUT = –(VIN – IOUT × RO), where RO is ~23Ω. At 10mA load, VOUT drops to ~–4.77V. For regulated –5V, consider the MAX868 or MAX1757, not the MAX1721EUT-T.
What capacitor values are required for the MAX1721EUT-T?
The MAX1721EUT-T requires two 1µF ceramic capacitors: C1 (flying capacitor) between C1+ and C1−, and C2 (output reservoir) between OUT and GND. A third 1µF bypass capacitor (C3) between IN and GND is recommended. All must be low-ESR X7R or better to maintain 23Ω output resistance and low ripple.
Does the MAX1721EUT-T support input voltages below +1.5V?
No - the absolute minimum input voltage for guaranteed operation of the MAX1721EUT-T is +1.5V, as specified in the Absolute Maximum Ratings and Electrical Characteristics tables. Operation below this level may result in failure to start, unstable oscillation, or undefined output behavior. The device is not characterized for sub-1.5V use.
How does temperature affect the output resistance of the MAX1721EUT-T?
Output resistance (RO) of the MAX1721EUT-T increases with temperature: it is ~23Ω at +25°C, rises to ~35Ω at –40°C, and reaches ~60Ω at +85°C (per Typical Operating Characteristics Figure MAX1720/21toc07). Designers must account for this drift when calculating worst-case output droop across the full –40°C to +85°C range.
MAX1721EUT-T Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Series:
- -
- Package/Case:
- SOT-23-6
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Obsolete
- Function:
- Ratiometric
- Output Configuration:
- Positive or Negative
- Topology:
- Charge Pump
- Output Type:
- Fixed
- Number of Outputs:
- 1
- Voltage - Input (Min):
- 1.5V
- Voltage - Input (Max):
- 5.5V
- Voltage - Output (Min/Fixed):
- -Vin, 2Vin
- Voltage - Output (Max):
- -
- Current - Output:
- 25mA
- Frequency - Switching:
- 60kHz ~ 200kHz
- Synchronous Rectifier:
- No
- Operating Temperature:
- -40°C ~ 85°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- SOT-6
MAX1721EUT-T FAQ
1.How can I place an order for MAX1721EUT-T through Aetrix?
Please submit a Request for Quotation (RFQ) for MAX1721EUT-T 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 MAX1721EUT-T reliable?
The price and inventory of MAX1721EUT-T are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MAX1721EUT-T is usually 5 days.
3.What payment methods are accepted for MAX1721EUT-T?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MAX1721EUT-T transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for MAX1721EUT-T?
MAX1721EUT-T orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your MAX1721EUT-T 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 MAX1721EUT-T?
For technical support, including MAX1721EUT-T datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MAX1721EUT-T requirements.
6.How does Aetrix verify that MAX1721EUT-T is sourced from the original manufacturer or authorized distributors?
All MAX1721EUT-T 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 MAX1721EUT-T meets industry standards.
7.What is the process for return or replacement of MAX1721EUT-T?
All MAX1721EUT-T units undergo pre-shipment inspection (PSI). If there is an issue with MAX1721EUT-T, 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 MAX1721EUT-T part is unused and in its original packaging.
Return procedure for MAX1721EUT-T:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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