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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:10,287
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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 6-pin SOT23 package, 1nA shutdown current, 23Ω typical output resistance at +5V input, wake-up time of 80µs from shutdown, and compatibility with low-ESR ceramic flying/output capacitors.
Technical Context
The MAX1721EUT+T implements a two-phase charge-pump topology using four on-chip power MOSFET switches to invert the input voltage without inductors. Its oscillator frequency is fixed at 125kHz, enabling compact 1µF capacitor sizing while maintaining low output impedance.
It features an inverting shutdown input (SHDN): driven high to enter shutdown mode, where OUT is actively pulled to GND via a 4Ω internal switch and supply current drops to 1nA. Output voltage follows VOUT ≈ –(VIN – IOUT × RO), with RO = 23Ω (typ) at +5V and +25°C, making load regulation predictable across 0–25mA.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | +1.5V to +5.5V - supports single-cell Li-ion, 3.3V, and 5V logic rails without external regulation. |
| Output Current | 25mA continuous - sufficient to bias op-amps, ADC references, or GaAs PA stages in handheld devices. |
| Oscillator Frequency | 125kHz - enables use of small 1µF ceramic capacitors while limiting EMI compared to higher-frequency pumps. |
| Voltage Conversion Efficiency | 99.9% (typ) - minimizes input power loss and thermal rise in battery-powered systems. |
| Shutdown Supply Current | 1nA (typ) - extends shelf life and runtime in always-on, intermittently active systems. |
| Output Resistance | 23Ω (typ at VIN = +5V, TA = +25°C) - defines load regulation slope: ~0.575V droop at 25mA. |
| Wake-Up Time | 80µs (max) - ensures rapid reactivation for burst-mode analog signal chains. |
Pinout & Package
MAX1721EUT+T is housed in a 6-pin SOT23-6 package (JEDEC MO-178AA), with 0.95mm pitch, 2.9mm × 1.6mm footprint, and exposed pad not connected internally.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 - C1+ | Positive terminal of flying capacitor | Connects to top plate of C1 during phase 1; requires low-ESR ceramic capacitor (1µF typical). |
| 2 - C1− | Negative terminal of flying capacitor | Connects to bottom plate of C1 during phase 2; forms charge-transfer path to output reservoir. |
| 3 - IN | Positive input supply rail | Accepts +1.5V to +5.5V; must be bypassed with ≥1µF ceramic capacitor near pin. |
| 4 - SHDN | Inverting shutdown control input | Drive HIGH to disable switching; OUT is actively shorted to GND via 4Ω switch in shutdown. |
| 5 - OUT | Inverting charge-pump output | Delivers –VIN (unregulated); output impedance dominates load regulation; connect to 1µF reservoir cap. |
| 6 - GND | Analog and power ground reference | Single ground connection; must tie directly to low-impedance PCB ground plane for noise control. |
Key Features
| Feature | Design Value |
|---|---|
| Logic-controlled shutdown | 1nA quiescent current with active GND pull-down on OUT - eliminates need for external discharge path. |
| Ultra-small footprint | 6-pin SOT23-6 package (2.9mm × 1.6mm) - fits within tight board areas typical of PDAs and sensor nodes. |
| High-efficiency inversion | 99.9% conversion efficiency at light loads - preserves battery energy in always-on monitoring circuits. |
| Minimal external components | Only two 1µF ceramic capacitors required - reduces BOM count, cost, and layout complexity. |
| Predictable load regulation | 23Ω typical output resistance - enables accurate output voltage estimation under varying load conditions. |
Applications
| Portable Instrumentation Power | GaAs Power Amplifier Bias |
|---|---|
|
Use Scenario: Generating –2.5V or –5V from a 3.3V or 5V microcontroller rail to power precision op-amps and ADC reference buffers in handheld multimeters or data loggers. IC Role / Device Role / Timing Role: Voltage inverter providing isolated negative rail; no timing interface - operates autonomously at fixed 125kHz. Use Value: Eliminates need for inductor-based DC/DC converters, reducing EMI and board area while delivering stable bias for 16-bit analog front-ends. |
Use Scenario: Supplying –3V bias to gate terminals of GaAs FET power amplifiers in UHF RFID readers and wireless sensor transceivers. IC Role / Device Role / Timing Role: High-efficiency charge-pump inverter delivering clean negative gate voltage; shutdown controlled by baseband processor GPIO. Use Value: Enables fast turn-on/turn-off of PA stage with <80µs wake-up, minimizing idle current and improving system-level duty-cycle efficiency. |
| Small LCD Panel Backlight Support | Battery-Operated Medical Sensors |
|
Use Scenario: Providing –5V supply for TFT-LCD source driver ICs in compact industrial HMI displays powered from a single 3.7V Li-ion cell. IC Role / Device Role / Timing Role: Compact voltage inverter supporting intermittent display operation; shutdown synchronized with display enable signal. Use Value: Achieves >99% efficiency at 10mA load, extending battery life beyond 100 hours per charge in low-duty-cycle applications. |
Use Scenario: Generating –1.5V from a 1.8V LDO to bias low-noise instrumentation amplifiers in wearable ECG/PPG modules. IC Role / Device Role / Timing Role: Low-quiescent-current inverter operating from ultra-low-voltage rail; output used for amplifier dual-supply configuration. Use Value: Maintains 1nA shutdown current and 99.9% efficiency at sub-5mA loads - critical for multi-week battery operation in clinical-grade sensors. |
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; 50µA quiescent current; same 6-pin SOT23 package and pinout. | Better low-noise performance at light loads due to lower switching frequency; higher output ripple at same capacitance. | Select MAX1720EUT+T when EMI sensitivity outweighs size constraints and 10µF caps are acceptable. |
| MAX860ESA+ | 50mA output capability; µMAX-8 package; no shutdown; regulated –2×VIN output option available (MAX868). | Higher power delivery but larger footprint and no logic control; requires different capacitor values and layout. | Choose MAX860ESA+ only when >25mA load current is required and shutdown functionality is unnecessary. |
Compared with MAX1721EUT+T, the MAX1720EUT+T trades higher capacitor size for lower EMI and better light-load stability, while the MAX860ESA+ offers greater output current at the cost of package size, missing shutdown, and no direct pin compatibility.
Availability
MAX1721EUT+T is available at Aetrix Electronics and suitable for portable instrumentation power, GaAs PA bias, small LCD panel support, and battery-operated medical sensors requiring stable component supply across extended production lifecycles.
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 voltage inversion in battery-constrained portable electronics - emphasizing minimal external components, nanoscale shutdown current, and SOT23 integration.
FAQ
What is the shutdown behavior of the MAX1721EUT+T?
The MAX1721EUT+T features an inverting shutdown input: driving SHDN high disables the charge pump, reduces supply current to 1nA (typ), and actively pulls the OUT pin to GND through a 4Ω internal switch. This eliminates residual output leakage and ensures safe discharge of downstream capacitors without external circuitry - a key advantage over non-shutdown inverters like the MAX828.
Can the MAX1721EUT+T generate regulated output voltages?
No, the MAX1721EUT+T is an unregulated voltage inverter - its output follows VOUT ≈ –(VIN – IOUT × RO), where RO is ~23Ω (typ). It does not include feedback or regulation circuitry. For regulated negative outputs (e.g., –2×VIN), Maxim recommends the MAX868, which integrates regulation but requires different external components and lacks shutdown control in the same form.
What capacitor types and values are recommended for the MAX1721EUT+T?
The MAX1721EUT+T requires two 1µF X7R or NP0 ceramic capacitors (low-ESR <100mΩ) for C1 (flying) and C2 (output reservoir), plus a 1µF input bypass capacitor (C3) at the IN pin. Tantalum or aluminum electrolytics are not recommended due to higher ESR, which degrades efficiency and increases output resistance beyond the specified 23Ω.
How does temperature affect the MAX1721EUT+T's output resistance?
Output resistance (RO) of the MAX1721EUT+T increases with temperature: from ~20Ω at –40°C to ~35Ω at +85°C (VIN = +5V). This variation directly impacts load regulation - e.g., at 25mA, VOUT droop rises from ~0.5V at room temperature to ~0.875V at max operating temperature - a critical factor in wide-temperature industrial designs.
Is the MAX1721EUT+T pin-compatible with other members of the MAX1719/MAX1720/MAX1721 family?
Yes, the MAX1721EUT+T shares identical 6-pin SOT23-6 pinout and package with MAX1719EUT+T and MAX1720EUT+T. However, SHDN polarity differs: MAX1721EUT+T and MAX1720EUT+T use noninverting shutdown (SHDN high = shutdown), while MAX1719EUT+T uses inverting shutdown (SHDN low = shutdown) - firmware or logic interface must be verified before substitution.
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:
- Active
- 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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