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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:1,574
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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 or adjustable +1.1V–VIN outputs, operates from +3V to +5.5V input, 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 programmable constant-off-time architecture (up to 350kHz), Idle Mode™ for light-load efficiency, 100% duty-cycle low-dropout operation, ±1% output accuracy, and integrated synchronous rectification eliminating external Schottky diodes.
Technical Context
The MAX1644EAE employs a current-mode, constant-off-time PWM control scheme with automatic transition between continuous-conduction constant-off-time mode (>0.2A load) and pulse-skipping Idle Mode™ (<0.2A load). Regulation is achieved by modulating PMOS on-time while holding off-time fixed via RTOFF.
It features a transconductance integrator amplifier (COMP pin), internal reference (1.100V typ), programmable AC load-regulation error (1% or 2%), and thermal shutdown with 15°C hysteresis. The device supports soft-start via external capacitor on SS, 100% duty-cycle operation near dropout, and undervoltage lockout at 2.6V (typ).
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Current | 2A continuous RMS; enables compact single-chip supply for CPU I/O and PC Card rails |
| Input Voltage Range | +3.0V to +5.5V; compatible with standard 3.3V/5V system rails without pre-regulation |
| Output Voltage Options | +3.3V or +2.5V (pin-selectable), or adjustable +1.1V to VIN; supports legacy and low-voltage logic domains |
| Switching Frequency | Up to 350kHz (programmable via RTOFF); balances EMI, inductor size, and efficiency trade-offs |
| Efficiency | Up to 95%; enabled by synchronous rectification and low RON internal switches (70mΩ/100mΩ @ VIN = 4.5V/3V) |
| Accuracy | ±1% output voltage tolerance; ensures stable core/I/O rail compliance under line/load/temperature variation |
| Shutdown Current | <1µA; meets ultra-low-power requirements during system sleep or standby states |
Pinout & Package
MAX1644EAE is housed in a 16-pin SSOP (Shrink Small Outline Package) with 0.65mm pitch, JEDEC MO-150 compliant, and thermal resistance θJA = 60°C/W (with 0.5 in² copper).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| SHDN | Logic-level shutdown control | Drives internal circuitry and MOSFETs into high-impedance state; draws <1µA supply current when low |
| IN (Pins 2,4) | Main power input | Supplies internal PMOS switch; accepts +3V to +5.5V; requires local 2.2µF/10Ω RC filter |
| LX (Pins 3,14,16) | Switch node | Connects drains of internal PMOS/NMOS; interfaces directly to inductor; high dv/dt node requiring tight layout |
| PGND (Pins 13,15) | Power ground return | Internally tied to NMOS source; must be connected to input/output capacitor grounds to minimize switching noise |
| FBSEL | Feedback configuration select | Determines output voltage (GND/REF/VCC/unconnected) and AC load-regulation error (1%/2%) |
| FB | Voltage feedback input | Compares divided output to 1.100V reference; connects directly to output (fixed) or resistor divider (adjustable) |
| SS | Soft-start timing | External capacitor sets inrush current ramp rate; limits peak input surge during startup and wake-up |
| TOFF | Off-time programming | Resistor-to-ground sets constant off-time (0.4–4µs), defining switching frequency and light-load behavior |
| COMP | Integrator compensation | External capacitor (≥470pF) stabilizes control loop; adjusts transient response vs. stability trade-off |
| REF | Internal reference output | 1.100V ±1% precision reference; bypassed with 1µF ceramic capacitor to GND for noise immunity |
| VCC | Analog supply input | Powers internal analog circuitry; requires dedicated 2.2µF/10Ω low-pass filter per datasheet layout guidelines |
| GND | Analog ground reference | Reference for FB, COMP, REF; must be isolated from PGND except at single-point star ground |
Key Features
| Feature | Design Value |
|---|---|
| Synchronous rectification | Eliminates external Schottky diode; reduces conduction loss and improves efficiency by ~5–8% over diode-based designs |
| Idle Mode™ operation | Skips switching cycles below 0.2A load; maintains >85% efficiency at 10mA load where conventional PWM drops to <60% |
| Programmable constant-off-time | Enables precise frequency setting (up to 350kHz) via single RTOFF; avoids frequency drift with input/output variation |
| 100% duty-cycle low-dropout | PMOS remains fully on when VIN ≈ VOUT; dropout voltage = IOUT × RON,P, enabling operation down to VIN = VOUT + 200mV @ 1A |
| Adjustable soft-start | External capacitor on SS pin linearly ramps current limit from 0 to 2.9A; prevents input rail collapse during cold start |
Applications
| PC Card Power Supply | CPU Daughter Card I/O Rail |
|---|---|
Use Scenario: Providing regulated +3.3V power to PCMCIA/CardBus peripherals in portable computing systems. IC Role / Device Role / Timing Role: Primary synchronous buck regulator converting +5V main rail to +3.3V I/O supply with minimal external components. Use Value: Internal switches and pin-selectable output eliminate 4–6 discrete parts; SSOP package fits space-constrained PC card edge connectors. | Use Scenario: Generating stable +2.5V or +3.3V for CPU address/data buffers and interface logic on add-in daughter cards. IC Role / Device Role / Timing Role: High-efficiency point-of-load regulator supporting dynamic load steps up to 2A with fast transient response. Use Value: Idle Mode™ sustains >88% efficiency at 50mA idle current; 95% peak efficiency reduces thermal load on densely packed boards. |
| Desktop Bus-Termination Board | Notebook Subsystem Supply |
Use Scenario: Delivering low-noise +3.3V to SCSI, PCI, or ISA bus termination networks in desktop motherboards. IC Role / Device Role / Timing Role: Low-ripple, tightly regulated buck converter with integrated soft-start to prevent bus initialization glitches. Use Value: ±1% output accuracy and 2% AC load regulation ensure signal integrity across temperature; TOFF programming minimizes EMI in mixed-signal environments. | Use Scenario: Powering memory controllers, display interfaces, or audio codecs in subnotebook platforms with strict power budget. IC Role / Device Role / Timing Role: Dual-mode regulator operating in PWM under load and Idle Mode™ during suspend, reducing quiescent current to 360µA. Use Value: Shutdown current <1µA extends battery life; 16-pin SSOP footprint allows routing beneath BGA processors for compact layouts. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar synchronous step-down regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| TPS54202DRCT | 4.5–17V input range; 2A output; uses voltage-mode control; no Idle Mode™; 500kHz max frequency | Requires higher input voltage; less efficient below 0.1A due to fixed-frequency operation | Preferred for industrial 12V-input systems needing wider VIN range and higher fSW |
| RT8205AZSP | 2.7–5.5V input; 2A output; constant-on-time control; 1.2MHz switching; no adjustable soft-start | Higher switching frequency reduces inductor size but increases switching loss; lacks programmable off-time | Selected when board space is critical and 1.2MHz operation is acceptable for EMI profile |
Compared with TPS54202DRCT and RT8205AZSP, the MAX1644EAE offers superior light-load efficiency via Idle Mode™, precise constant-off-time tuning for optimal noise/size/efficiency balance, and pin-selectable fixed outputs-making it uniquely suited for 3.3V/5V-powered portable and embedded computing rails.
Availability
MAX1644EAE is available at Aetrix Electronics and suitable for PC card power supplies, CPU daughter card I/O rails, and desktop bus-termination boards requiring stable component supply, long-term lifecycle support, and guaranteed traceable sourcing.
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 computing, communications, and industrial markets.
The MAX1644EAE belongs to Maxim's low-voltage synchronous buck regulator product line, designed specifically for space-constrained, efficiency-critical portable computing applications including PC Cards, CPU daughter cards, and bus-termination boards.
FAQ
What is the maximum continuous output current supported by the MAX1644EAE?
The MAX1644EAE delivers up to 2A of continuous RMS output current. This rating is validated across the full operating temperature range (–40°C to +85°C) and input voltage range (+3.0V to +5.5V), assuming proper PCB layout with ≥0.5 in² copper area for thermal dissipation. Peak current capability reaches 2.9A during soft-start, but sustained operation above 2A risks thermal shutdown.
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 high-side switch and a 0.10Ω NMOS synchronous rectifier switch, enabling full synchronous rectification. This eliminates conduction losses associated with Schottky diodes and improves efficiency by 5–8% compared to non-synchronous buck converters.
How is the output voltage configured on the MAX1644EAE?
The MAX1644EAE supports three output configurations: +3.3V (FBSEL unconnected), +2.5V (FBSEL tied to VCC), or adjustable +1.1V to VIN (FBSEL tied to GND or REF with external resistor divider on FB). The internal 1.100V reference and ±1% accuracy ensure tight regulation across all modes without trimming.
What is the purpose of the TOFF pin on the MAX1644EAE?
The TOFF pin on the MAX1644EAE sets the constant off-time period via an external resistor to ground, directly determining the switching frequency in PWM mode. With RTOFF = 150kΩ, tOFF = 1.26µs yields ~300kHz at VIN = 5V/VOUT = 3.3V. This programmability allows optimization of efficiency, EMI, and component size without changing ICs.
Can the MAX1644EAE operate in 100% duty-cycle mode?
Yes, the MAX1644EAE enters 100% duty-cycle mode when the input voltage approaches the output voltage. In this mode, the internal PMOS switch remains continuously on, and dropout voltage equals IOUT × RON,P (70mΩ typ at VIN = 4.5V). This enables regulation down to VIN = VOUT + ~140mV at 2A, critical for low-headroom applications like battery-powered systems.
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:
- Obsolete
- 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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