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Analog Devices Inc./Maxim Integrated MAX1644EAE+
- Part No.:
- MAX1644EAE+
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Package:
- 16-SSOP (0.209", 5.30mm Width)
- Datasheet:
-
MAX1644EAE+.pdf
- Description:
- IC REG BUCK ADJ 2A 16SSOP
- Quantity:
- Payment:
- Shipping:
Inventory:3,822
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Product details
Overview
The MAX1644EAE+ from Maxim Integrated is a constant-off-time, current-mode PWM synchronous step-down DC-DC regulator delivering up to 2A continuous output current. It integrates 0.10Ω PMOS and 0.10Ω NMOS power switches, supports pin-selectable +3.3V/+2.5V outputs or adjustable 1.1V–VIN operation, and achieves up to 95% efficiency in PC card, CPU daughter card, and bus-termination board applications.
For engineers reviewing the MAX1644EAE+ datasheet, MAX1644EAE+ pinout, MAX1644EAE+ application, or MAX1644EAE+ equivalent, key selection considerations include its 3V–5.5V input range, programmable off-time (up to 350kHz), Idle Mode™ for light-load efficiency, 100% duty-cycle low-dropout operation, and integrated soft-start with <1µA shutdown current.
Technical Context
The MAX1644EAE+ employs a proprietary current-mode, constant-off-time PWM architecture that dynamically shifts between continuous-conduction mode (above 0.2A load) and pulse-skipping Idle Mode™ (below 0.2A), minimizing gate-charge and transition losses. Regulation is achieved by modulating PMOS on-time while holding off-time fixed via external RTOFF.
It features internal synchronous rectification eliminating external Schottky diodes, a transconductance integrator amplifier at COMP for precise DC regulation, and a summing comparator combining voltage error, integrated error, and sensed switch current-enabling fast line/load transient response without high-gain amplifiers.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | +3.0V to +5.5V - supports standard 3.3V and 5V system rails without external level-shifting. |
| Output Current | 2A continuous - sufficient for CPU I/O, PC Card logic, and bus-termination loads. |
| Efficiency | Up to 95% - enabled by synchronous rectification and low RDS(ON) internal switches (70mΩ/100mΩ at VIN = 4.5V/3V). |
| Switching Frequency | Up to 350kHz - programmable via RTOFF to balance EMI, inductor size, and efficiency. |
| Shutdown Current | <1µA - disconnects input from output and disables all internal circuitry for ultra-low standby power. |
| Output Accuracy | ±1% - guaranteed over temperature and line/load, critical for stable digital supply rails. |
| Dropout Behavior | 100% duty cycle - maintains regulation when VIN approaches VOUT, with dropout voltage = IOUT × RON,P. |
Pinout & Package
The MAX1644EAE+ is housed in a 16-pin SSOP package (5.3mm width, JEDEC MO-150 compliant) with exposed thermal pad not connected internally; recommended copper area ≥0.5 in² for θJA = 60°C/W (no airflow).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| SHDN | Logic-level shutdown control | Pull low to disable reference, control logic, and MOSFETs; reduces supply current below 1µA. |
| IN (Pins 2,4) | Main power input | Supplies internal PMOS switch; accepts 3V–5.5V; requires local 2.2µF/10Ω low-pass filter at VCC. |
| LX (Pins 3,14,16) | Switch node | Drain connection of internal PMOS/NMOS; connects directly to inductor; carries high di/dt current. |
| PGND (Pins 13,15) | Power ground return | Internal connection to NMOS source; must be tied to input/output capacitor grounds to minimize noise loops. |
| FBSEL | Output voltage mode select | GND = 1% AC load regulation (adjustable); REF = 2%; unconnected/VCC = preset 3.3V/2.5V. |
| FB | Voltage feedback input | Compares output (direct or resistor-divided) to 1.1V internal reference; bias current <200nA. |
| COMP | Integrator compensation node | Connects external capacitor (≥470pF) to VCC to stabilize control loop and ensure DC accuracy. |
| SS | Soft-start timing node | Capacitor to GND sets inrush current ramp rate; 5µA current source charges CSS to limit peak ILIMIT to 2.9A. |
Key Features
| Feature | Design Value |
|---|---|
| Synchronous rectification | Eliminates external Schottky diode; uses matched 0.10Ω NMOS switch to reduce conduction loss and improve efficiency. |
| Idle Mode™ operation | Skips switching cycles below 0.2A load, reducing gate-charge loss and maintaining >85% efficiency at 1mA output. |
| Programmable constant-off-time | RTOFF from 39kΩ to 470kΩ sets tOFF from 0.4µs to 4µs, enabling frequency optimization across input/output conditions. |
| Adjustable soft-start | External capacitor at SS controls current-limit ramp time, preventing input surge during startup and shutdown recovery. |
| 100% duty-cycle low-dropout | PMOS remains fully on when VIN ≈ VOUT; dropout voltage determined solely by IOUT × RON,P (70mΩ typical at 4.5V). |
Applications
| PC Card Power Supply | CPU Daughter Card Rail |
|---|---|
Use Scenario: Providing regulated +3.3V power to PCMCIA/CardBus peripherals in portable systems with tight space and thermal constraints. IC Role / Device Role / Timing Role: Primary step-down regulator converting +5V host bus to +3.3V logic rail; manages dynamic load steps during card insertion and data transfer. Use Value: Internal synchronous switches and Idle Mode™ sustain >90% efficiency across 10mA–2A load range, reducing heat and extending battery life. | Use Scenario: Generating stable +2.5V or +3.3V supply for CPU I/O buffers and interface logic on add-in daughter cards. IC Role / Device Role / Timing Role: High-current, low-noise DC-DC converter with fast transient response; handles burst-mode I/O activity without output droop. Use Value: Constant-off-time architecture delivers sub-10µs recovery from 50% load steps, ensuring signal integrity on high-speed buses. |
| Desktop Bus-Termination Board | Notebook Subsystem Regulator |
Use Scenario: Powering parallel SCSI or PCI termination networks requiring precise +3.3V at up to 2A with minimal ripple. IC Role / Device Role / Timing Role: Fixed-output buck regulator with ±1% accuracy and low output impedance; supplies termination current while rejecting supply noise. Use Value: Integrated 0.10Ω switches and 1.1V reference enable <15mV output deviation across full load and temperature range. | Use Scenario: Generating core logic voltage (e.g., +1.5V) from +3.3V or +5V battery rail in space-constrained notebook subsystems. IC Role / Device Role / Timing Role: Adjustable-output synchronous buck converter; configured via FBSEL/GND and resistor divider for 1.1V–VIN range. Use Value: Programmable RTOFF allows 300kHz operation to shrink inductor size while maintaining >88% efficiency at 1.5V/2A. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar step-down regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| TPS54202DRCT | 4.5V–17V input; 2A; 500kHz fixed freq; no Idle Mode; requires external bootstrap cap | Better suited for higher-input industrial rails; lacks light-load efficiency optimization | Select when input exceeds 5.5V or fixed-frequency EMI control is required. |
| RT8205AZSP | 2.7V–5.5V input; 2A; 600kHz; integrated boot diode; no programmable off-time | Higher switching frequency enables smaller magnetics but increases light-load quiescent current (>100µA) | Prefer for compact designs where PCB area outweighs light-load efficiency. |
Compared with the MAX1644EAE+, the TPS54202DRCT supports wider input voltage but lacks Idle Mode™ and requires external components for bootstrap operation, while the RT8205AZSP offers higher frequency and integrated boot diode but trades off light-load efficiency for size reduction-making the MAX1644EAE+ optimal for 3V–5.5V battery-powered applications demanding ultra-low shutdown current and adaptive light-load performance.
Availability
The MAX1644EAE+ is available at Aetrix Electronics and suitable for PC card power supplies, CPU daughter card rails, and desktop bus-termination boards requiring stable component supply, long-term lifecycle support, and lead-free compliance.
Supply support for MAX1644EAE+ 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, computing, and communications markets.
The MAX1644EAE+ belongs to Maxim's low-voltage synchronous buck regulator product line, designed specifically for space-constrained, efficiency-critical applications in portable and embedded computing systems where internal switches, programmable frequency, and ultra-low shutdown current are essential.
FAQ
What output voltage options does the MAX1644EAE+ support?
The MAX1644EAE+ supports three output configurations: pin-selectable +3.3V (FBSEL unconnected), +2.5V (FBSEL = VCC), or adjustable 1.1V to VIN (FBSEL = GND or REF with external resistor divider). The internal 1.1V reference and ±1% accuracy ensure stable regulation across all modes, and AC load-regulation error is selectable at 1% or 2% depending on FBSEL state.
How does the MAX1644EAE+ achieve high efficiency at light loads?
The MAX1644EAE+ achieves high light-load efficiency through its proprietary Idle Mode™, which skips switching cycles when load current falls below ~0.2A. This eliminates unnecessary gate-charge and transition losses while maintaining regulation via pulse-frequency modulation. Measured data shows >85% efficiency at 1mA output, significantly outperforming fixed-frequency alternatives with higher quiescent current.
What is the role of the TOFF pin on the MAX1644EAE+?
The TOFF pin on the MAX1644EAE+ sets the constant off-time period for the PMOS switch via an external resistor (RTOFF) connected to GND. This resistor determines switching frequency up to 350kHz and enables optimization of trade-offs among efficiency, EMI, inductor size, and cost. Typical RTOFF values range from 39kΩ to 470kΩ, yielding off-times from 0.4µs to 4µs per the device's linear scaling equation.
Does the MAX1644EAE+ require an external Schottky diode?
No, the MAX1644EAE+ does not require an external Schottky diode. It integrates both a 0.10Ω PMOS power switch and a 0.10Ω NMOS synchronous rectifier switch, enabling full synchronous rectification. This eliminates conduction losses associated with Schottky forward voltage drop and reduces component count, PCB area, and thermal stress compared to nonsynchronous buck converters.
What thermal design guidance applies to the MAX1644EAE+ SSOP package?
The MAX1644EAE+ in 16-pin SSOP has a junction-to-ambient thermal resistance (θJA) of 60°C/W with 0.5 in² copper area and no airflow. To maintain safe operation at 2A, designers must minimize high-current ground loops by tying IN capacitor ground, OUT capacitor ground, and PGND together; use ≥2mm wide traces for IN/LX; and place LX components close to the IC. Airflow further reduces θJA, and thermal shutdown activates at 150°C with 15°C hysteresis.
MAX1644EAE+ Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Series:
- -
- Package/Case:
- 16-SSOP (0.209", 5.30mm Width)
- Packaging:
- Tube
- Product Status:
- Active
- Function:
- Step-Down
- Output Configuration:
- Positive
- Topology:
- Buck
- Output Type:
- Adjustable (Programmable)
- Number of Outputs:
- 1
- Voltage - Input (Min):
- 3V
- Voltage - Input (Max):
- 5.5V
- Voltage - Output (Min/Fixed):
- 1.1V (2.525V, 3.33V)
- Voltage - Output (Max):
- 5.5V
- Current - Output:
- 2A
- Frequency - Switching:
- Up to 350kHz
- Synchronous Rectifier:
- Yes
- Operating Temperature:
- -40°C ~ 85°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 16-SSOP
MAX1644EAE+ FAQ
1.How can I place an order for MAX1644EAE+ through Aetrix?
Please submit a Request for Quotation (RFQ) for MAX1644EAE+ 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 MAX1644EAE+ reliable?
The price and inventory of MAX1644EAE+ are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MAX1644EAE+ is usually 5 days.
3.What payment methods are accepted for MAX1644EAE+?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MAX1644EAE+ transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for MAX1644EAE+?
MAX1644EAE+ orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your MAX1644EAE+ 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 MAX1644EAE+?
For technical support, including MAX1644EAE+ datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MAX1644EAE+ requirements.
6.How does Aetrix verify that MAX1644EAE+ is sourced from the original manufacturer or authorized distributors?
All MAX1644EAE+ 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 MAX1644EAE+ meets industry standards.
7.What is the process for return or replacement of MAX1644EAE+?
All MAX1644EAE+ units undergo pre-shipment inspection (PSI). If there is an issue with MAX1644EAE+, 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 MAX1644EAE+ part is unused and in its original packaging.
Return procedure for MAX1644EAE+:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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