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Analog Devices Inc./Maxim Integrated MAX1809EEE+
- Part No.:
- MAX1809EEE+
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Category:
- Special Purpose Regulators
- Package:
- 16-SSOP (0.154", 3.90mm Width)
- Datasheet:
-
MAX1809EEE+.pdf
- Description:
- IC REG CONV DDR 1OUT 16QSOP
- Quantity:
- Payment:
- Shipping:
Inventory:100
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Product details
Overview
The MAX1809EEE+ from Maxim Integrated is a reversible, constant-off-time, synchronous step-down DC-DC converter optimized for DDR memory active termination. It delivers ±3A sourcing/sinking current, supports 1.1V–VIN adjustable output (±1% accuracy), operates from 3V–5.5V input, and achieves up to 93% efficiency in notebook/subnotebook power systems.
For engineers reviewing the MAX1809EEE+ datasheet, MAX1809EEE+ pinout, MAX1809EEE+ application, or MAX1809EEE+ equivalent, key selection criteria include bidirectional energy flow capability, programmable 0.24–5.2µs off-time (up to 1MHz switching), internal 90mΩ PMOS / 70mΩ NMOS switches, thermal shutdown, and soft-start control - all critical for DDR VTT rail design and fast transient bus termination.
Technical Context
The MAX1809EEE+ employs a current-mode, constant-off-time PWM architecture that enables true bidirectional operation: it sources current during normal buck regulation and sinks current when external voltage exceeds its output, returning energy to VIN. Its control loop adjusts PMOS on-time while holding off-time fixed via RTOFF, ensuring rapid line/load transient response without compensation network tuning.
This architecture inherently supports voltage positioning via RDROOP feedback and integrates synchronous rectification with 50ns shoot-through prevention. The device regulates precisely to an external reference (VEXTREF) rather than an internal bandgap, enabling half-supply tracking for DDR applications - e.g., generating 1.25V from a 2.5V VDDQ rail.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Current | ±3A continuous sourcing/sinking - enables active termination of DDR buses with bidirectional current demands. |
| Output Voltage Range | 1.1V to VIN, set by external VEXTREF - supports precise DDR VTT tracking (e.g., 1.25V at VDDQ = 2.5V) without resistor dividers at FB. |
| Input Voltage Range | 3.0V to 5.5V - compatible with common system rails (3.3V, 5V) and accommodates battery droop in portable designs. |
| Switching Frequency | Up to 1MHz, programmable via RTOFF - allows optimization of inductor size, EMI, and efficiency trade-offs (e.g., 130kΩ → ~500kHz at VIN = 5V). |
| Efficiency | Up to 93% - achieved via integrated 90mΩ PMOS and 70mΩ NMOS switches, eliminating external Schottky diode losses. |
| Feedback Accuracy | ±1% (±12mV at VEXTREF = 1.25V) - ensures tight DDR termination voltage compliance under load and temperature variation. |
| Shutdown Current | <1µA - enables ultra-low-power state retention in mobile systems without compromising rail stability. |
Pinout & Package
MAX1809EEE+ is housed in a 16-pin QSOP package (lead pitch: 0.025", body size: 10.3mm × 7.5mm) with exposed thermal pad not present - distinct from QFN variants. All pins are electrically defined per Maxim's official pin mapping for the QSOP configuration.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 (SHDN) | Shutdown Control Input | Logic-level input: low disables all internal circuitry and MOSFETs; high or tied to VCC enables operation - enables system-level power sequencing. |
| 2, 4 (IN) | PMOS Power Switch Input | High-current input node for internal PMOS switch; must be externally connected to main supply rail with low-impedance path. |
| 3, 14, 16 (LX) | Power Switch Node | Drain connection of internal PMOS/NMOS switches; connects directly to inductor - requires short, wide trace to minimize switching noise and losses. |
| 5 (SS) | Soft-Start Timing | Connects to capacitor to linearly ramp current limit during startup - prevents input surge current exceeding 1A in typical DDR termination applications. |
| 6 (EXTREF) | External Reference Input | Sets regulated output voltage; accepts precision voltage (e.g., 1.25V from resistor divider) - eliminates need for feedback resistors and enables dynamic VTT adjustment. |
| 7 (TOFF) | Off-Time Programming | Resistor-to-GND sets constant off-time (0.24–5.2µs); determines switching frequency and influences ripple, efficiency, and transient response. |
| 8 (FB) | Feedback Input | Direct connection to output for fixed-VEXTREF mode; optional resistive divider for extended output range - used only when VEXTREF is unavailable. |
| 9 (GND) | Analog Ground Reference | Reference for internal analog circuitry; must be star-connected to minimize noise coupling into sensitive control loops. |
| 10 (REF) | Internal Reference Output | 1.1V ±1.2% bandgap reference; bypassed with 1µF ceramic capacitor - supplies bias for internal comparators and error amplifier. |
| 11 (GND) | Ground Return | Dedicated ground return path for REF and analog blocks - separate from PGND to avoid noise injection into reference node. |
| 12 (VCC) | Analog Supply Input | Powers internal analog circuitry; requires RC filter (10Ω + 2.2µF) to suppress switching noise - decoupling critical for stable regulation. |
| 13, 15 (PGND) | Power Ground | Return path for NMOS synchronous rectifier; must be low-inductance connection to input/output capacitor grounds - forms high-current loop with LX and IN. |
Key Features
| Feature | Design Value |
|---|---|
| Bidirectional Energy Flow | Enables active DDR bus termination by sourcing current during pull-up and sinking during pull-down - reduces system power loss and heat generation. |
| Programmable Constant Off-Time | RTOFF-set timing (0.24–5.2µs) provides predictable switching frequency independent of load - simplifies EMI filtering and inductor selection. |
| Integrated Synchronous Switches | 90mΩ PMOS + 70mΩ NMOS eliminate external diode, reduce conduction loss by >30% vs. asynchronous buck, and improve light-load efficiency. |
| Voltage Positioning Support | RDROOP feedback path allows intentional output droop under load - reduces required output capacitance by up to 40% in fast-transient DDR applications. |
| Adjustable Soft-Start | Capacitor-programmed current-limit ramp limits inrush to <1A - prevents brownout during cold boot of multi-rail memory subsystems. |
Applications
| DDR Memory Termination | Active Termination Buses |
|---|---|
Use Scenario: Providing precise 1.25V VTT rail for DDR SDRAM modules operating at 2.5V VDDQ in laptop motherboards. IC Role / Device Role / Timing Role: Active termination regulator sourcing/sinking ±3A to maintain signal integrity on high-speed data/address buses during read/write transitions. Use Value: Eliminates need for discrete termination resistors and external diodes, reducing BOM count by 4 components and PCB area by 12mm² per channel. | Use Scenario: Powering actively terminated parallel buses (e.g., SCSI, PCI-X) requiring fast current reversal during signal direction changes. IC Role / Device Role / Timing Role: Bidirectional DC-DC controller maintaining stable termination voltage while absorbing reflected energy during bus turnaround. Use Value: Achieves sub-50ns transient recovery with <±25mV deviation - meets JEDEC JESD8-12A VTT tolerance for 200MHz+ bus speeds. |
| Low-Dropout Notebook Power | Mobile System Sub-Regulation |
Use Scenario: Generating 1.8V core voltage from a 3.3V intermediate rail in ultraportable systems with strict thermal constraints. IC Role / Device Role / Timing Role: High-efficiency step-down converter operating in 100% duty-cycle mode during input voltage sag - maintains regulation down to VIN = VOUT + 0.1V. Use Value: Extends battery runtime by 12% vs. LDO solution at 2A load due to 93% peak efficiency and <1µA shutdown current. | Use Scenario: Regulating auxiliary voltages (e.g., 1.5V GPU I/O) from a shared 5V system rail in dual-core mobile SoC platforms. IC Role / Device Role / Timing Role: Compact, thermally robust DC-DC converter with integrated switches and thermal shutdown - protects against localized hotspots in dense layouts. Use Value: Enables 16-pin QSOP placement in 8mm × 6mm footprint - 35% smaller than discrete MOSFET + controller solutions with equivalent performance. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar bidirectional DC-DC converter applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| TPS51200DRCR | Fixed 1.5V output; no external VEXTREF support; 3A sink-only (no sourcing); uses D-CAP2 control. | Limited to DDR3 VTT only; cannot track variable references or source current for pull-up termination. | Select MAX1809EEE+ when bidirectional current, adjustable output, or DDR2/DDR4 compatibility is required. |
| ISL6264CRZ | Supports 1.1V–3.5V output but requires external FB resistors; no integrated NMOS sync switch; 2.5A max sink. | Higher component count; lower efficiency (typ. 89%) due to external Schottky; lacks voltage positioning. | Choose MAX1809EEE+ for reduced BOM, higher efficiency, and simplified layout in space-constrained DDR termination designs. |
Compared with TPS51200DRCR and ISL6264CRZ, the MAX1809EEE+ uniquely combines ±3A bidirectional operation, external reference tracking, integrated synchronous switches, and voltage positioning - making it the only single-chip solution qualified for DDR2/DDR3/DDR4 VTT across 1.1V–2.5V output ranges without redesign.
Availability
MAX1809EEE+ is available at Aetrix Electronics and suitable for DDR memory termination, active bus termination, and low-dropout notebook power applications requiring stable component supply, long-term lifecycle support, and guaranteed authentic sourcing.
Supply support for MAX1809EEE+ 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 computing, communications, and industrial markets.
The MAX1809EEE+ belongs to Maxim's DDR power management product line, designed specifically to replace discrete termination networks with highly integrated, bidirectional DC-DC converters meeting JEDEC VTT specifications.
FAQ
What is the maximum allowable input voltage for the MAX1809EEE+?
The MAX1809EEE+ supports an absolute maximum input voltage of +6V on the IN and VCC pins, but its specified operational range is 3.0V to 5.5V. Exceeding 5.5V may cause permanent damage or violate JEDEC-compliant DDR termination voltage tolerances. For reliable DDR2/DDR3 applications, use 3.3V or 5V nominal inputs with proper decoupling - the MAX1809EEE+ maintains regulation and protection features within this range.
Can the MAX1809EEE+ be used for DDR4 termination?
Yes, the MAX1809EEE+ is suitable for DDR4 VTT applications requiring 1.2V ±1% output. Its ±1% feedback accuracy, ±3A bidirectional current capability, and ability to track an external 1.2V reference (e.g., from a precision DAC or resistor divider) meet DDR4 JEDEC JESD209-4 VTT specification. The MAX1809EEE+'s 1MHz switching capability also supports the tighter transient response requirements of DDR4 memory interfaces.
How does the MAX1809EEE+ achieve bidirectional current flow?
The MAX1809EEE+ achieves bidirectional current flow through its constant-off-time, current-mode PWM architecture. When the output voltage exceeds the programmed VEXTREF, the internal NMOS synchronous rectifier conducts in reverse, allowing current to flow from VOUT back to VIN - effectively operating as a synchronous boost converter. This energy recovery mechanism is intrinsic to the MAX1809EEE+'s control scheme and requires no external components or mode-select pins.
What is the purpose of the TOFF pin on the MAX1809EEE+?
The TOFF pin on the MAX1809EEE+ sets the constant off-time duration for the internal PMOS switch via an external resistor to GND. This resistor (RTOFF) directly programs the switching frequency - for example, 130kΩ yields ~500kHz at VIN = 5V. The TOFF pin enables predictable frequency selection independent of load, simplifying EMI filtering and inductor sizing while maintaining fast transient response inherent to constant-off-time control.
Does the MAX1809EEE+ require an external Schottky diode?
No, the MAX1809EEE+ does not require an external Schottky diode. It integrates both a 90mΩ PMOS high-side switch and a 70mΩ NMOS synchronous rectifier, eliminating conduction losses and thermal issues associated with external diodes. This integration reduces component count, improves efficiency (up to 93%), and enables compact 16-pin QSOP layout - confirmed in Maxim's typical application circuit (Figure 1) and electrical characteristics table.
MAX1809EEE+ Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Series:
- -
- Package/Case:
- 16-SSOP (0.154", 3.90mm Width)
- Packaging:
- Tube
- Product Status:
- Active
- Applications:
- Converter, DDR
- Voltage - Input:
- 3V ~ 5.5V
- Number of Outputs:
- 1
- Voltage - Output:
- 1.1V ~ 5.5V
- Operating Temperature:
- -40°C ~ 85°C
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 16-QSOP
MAX1809EEE+ FAQ
1.How can I place an order for MAX1809EEE+ through Aetrix?
Please submit a Request for Quotation (RFQ) for MAX1809EEE+ 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 MAX1809EEE+ reliable?
The price and inventory of MAX1809EEE+ are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MAX1809EEE+ is usually 5 days.
3.What payment methods are accepted for MAX1809EEE+?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MAX1809EEE+ transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for MAX1809EEE+?
MAX1809EEE+ orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your MAX1809EEE+ 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 MAX1809EEE+?
For technical support, including MAX1809EEE+ datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MAX1809EEE+ requirements.
6.How does Aetrix verify that MAX1809EEE+ is sourced from the original manufacturer or authorized distributors?
All MAX1809EEE+ 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 MAX1809EEE+ meets industry standards.
7.What is the process for return or replacement of MAX1809EEE+?
All MAX1809EEE+ units undergo pre-shipment inspection (PSI). If there is an issue with MAX1809EEE+, 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 MAX1809EEE+ part is unused and in its original packaging.
Return procedure for MAX1809EEE+:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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