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Analog Devices Inc./Maxim Integrated MAX1809ETI+
- Part No.:
- MAX1809ETI+
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Category:
- Special Purpose Regulators
- Package:
- 28-WFQFN Exposed Pad
- Datasheet:
-
MAX1809ETI+.pdf
- Description:
- IC REG CONV DDR 1OUT 28TQFN
- Quantity:
- Payment:
- Shipping:
Inventory:2,050
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Product details
Overview
The MAX1809ETI+ from Maxim Integrated is a reversible-energy-flow, constant-off-time, synchronous step-down DC-DC converter optimized for DDR memory active termination. It delivers ±3A sourcing/sinking current, supports 3V–5.5V input and 1.1V–VIN adjustable output, achieves up to 93% efficiency, and operates at up to 1MHz switching frequency in notebook/subnotebook power systems.
For engineers reviewing the MAX1809ETI+ datasheet, MAX1809ETI+ pinout, MAX1809ETI+ application, or MAX1809ETI+ equivalent, key selection considerations include its bidirectional current capability, internal 90mΩ PMOS / 70mΩ NMOS switches, ±1% output accuracy, programmable off-time via RTOFF, and thermal shutdown with 160°C trip point.
Technical Context
The MAX1809ETI+ implements a current-mode, constant-off-time PWM architecture that enables true bidirectional energy flow-sourcing current during normal buck operation and sinking current to return energy to the input rail during bus termination transients. Its control loop regulates output voltage by dynamically adjusting PMOS on-time while holding off-time fixed via external RTOFF.
This architecture delivers fast transient response, inherent pseudo-fixed-frequency behavior under steady load, and precise tracking of an external reference (VEXTREF) applied to the EXTREF pin. Internal synchronous rectification eliminates external Schottky diodes, and the device enters 100% duty-cycle mode for low-dropout operation when needed.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Current | ±3A continuous sourcing/sinking-supports DDR bus termination with rapid bidirectional load transients. |
| Input Voltage Range | 3.0V to 5.5V-compatible with standard notebook battery and adapter rails. |
| Output Voltage Range | 1.1V to VIN-adjustable via external reference (e.g., 1.25V for DDR2 VTT = VDDQ/2). |
| Switching Frequency | Up to 1MHz-set by RTOFF; enables compact magnetics and reduced EMI filtering requirements. |
| Efficiency | Up to 93%-achieved using internal 90mΩ PMOS and 70mΩ NMOS switches at VIN = 4.5V. |
| Feedback Accuracy | ±1% over temperature-ensures tight regulation for DDR termination voltage tolerance (±40mV at 1.25V). |
| Shutdown Current | <1µA-minimizes system standby power loss during sleep states. |
| Thermal Shutdown | 160°C with 15°C hysteresis-protects against sustained overload or poor PCB thermal design. |
Pinout & Package
The MAX1809ETI+ is housed in a 28-pin thin QFN package (5mm × 5mm, 0.5mm pitch) with an exposed backside thermal pad. Pin assignments are validated per Maxim's official datasheet revision 1 (9/02), with all LX, IN, PGND, and GND pins electrically tied internally as indicated in the pin description table.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| IN (Pins 2,4) | PMOS switch supply input | Connects directly to input rail; all IN pins must be shorted externally for low-impedance path and thermal sharing. |
| LX (Pins 3,18,19,23,25) | Switch node | Drain connection of internal PMOS/NMOS; ties to inductor; high di/dt node requiring minimized loop area. |
| PGND (Pins 17,20,21) | Power ground return | Internal connection to NMOS source; must be routed separately from analog GND and joined at single point near input cap. |
| GND (Pins 13,15) | Analog ground reference | Reference for FB, REF, SS, SHDN; exposed backside pad must connect to large analog ground plane. |
| EXTREF (Pin 7) | External voltage reference input | Sets regulated output voltage (VOUT = VEXTREF); must be ≤ VIN − 1.7V to avoid abnormal operation. |
| TOFF (Pin 8) | Off-time programming input | Resistor-to-GND sets tOFF (0.24–5.2µs), determining switching frequency and light-load behavior. |
| SHDN (Pin 27) | Logic-controlled shutdown | Active-low; pulls internal MOSFETs and bias circuits offline, reducing total supply current to <1µA. |
| SS (Pin 6) | Soft-start timing node | Capacitor-to-GND controls ramp rate of current limit during startup, limiting inrush into output capacitance. |
Key Features
| Feature | Design Value |
|---|---|
| Reversible energy flow | Enables active termination by sinking current back to input rail during DDR bus idle-to-active transitions-reducing heat and improving system efficiency. |
| Integrated PMOS/NMOS switches | 90mΩ/70mΩ typical RDS(ON) at VIN = 4.5V eliminates need for external Schottky diode and reduces BOM count and board space. |
| Adjustable soft-start | Programmable inrush current limiting via external capacitor on SS pin prevents input rail collapse during power-up or wake-from-sleep events. |
| 100% duty-cycle mode | Allows dropout operation down to VOUT ≈ VIN − ILOAD×RPMOS, critical for maintaining termination voltage during low-input conditions. |
| Voltage positioning support | RDROOP resistor network enables intentional droop to improve transient response margin without increasing total output capacitance. |
Applications
| DDR Memory Termination | Active Termination Buses |
|---|---|
Use Scenario: Providing precise, bidirectional termination voltage (e.g., 1.25V) for DDR2/DDR3 memory data/strobe lines in portable computing platforms. IC Role / Device Role / Timing Role: Active termination regulator delivering ±3A sourcing/sinking current synchronized to memory bus activity. Use Value: Maintains signal integrity during fast bidirectional bus transitions while recovering energy otherwise lost in passive termination resistors. | Use Scenario: Supplying dynamically adjustable termination for high-speed parallel buses such as Rambus or proprietary ASIC interconnects. IC Role / Device Role / Timing Role: Programmable termination voltage source tracking external reference, supporting variable bus voltage standards. Use Value: Eliminates discrete resistor networks and improves termination accuracy across temperature and process variation. |
| Low-Dropout Notebook Power Rails | Memory Subsystem Power Management |
Use Scenario: Generating auxiliary voltages (e.g., VTT, VREF) from main 3.3V or 5V rails where input-output differential is minimal. IC Role / Device Role / Timing Role: Synchronous buck converter operating in 100% duty-cycle mode to sustain output under low-VIN conditions. Use Value: Prevents termination voltage collapse during battery brownout or adapter sag, ensuring memory controller stability. | Use Scenario: Managing power delivery to DDR memory modules during dynamic frequency scaling and deep-sleep states. IC Role / Device Role / Timing Role: Fast-response regulator enabling rapid exit from low-power modes via controlled soft-start and shutdown sequencing. Use Value: Reduces wake-up latency and minimizes voltage overshoot/undershoot during state transitions. |
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 | Supports only sink-only operation (no sourcing); lower max current (±3A sink, 0A source); uses different control architecture (adaptive on-time). | Designed specifically for DDR3 VTT termination with integrated droop; lacks full bidirectional sourcing/sinking capability. | Select when DDR3-only compliance and lower cost are prioritized over general-purpose bidirectional flexibility. |
| ISL6264CRZ | Higher current rating (±6A); wider input range (2.5V–24V); requires external MOSFETs; no integrated switches. | Targeted at high-performance mobile platforms with multi-rail memory subsystems; greater design complexity due to external FETs. | Select when higher current headroom, extended input range, or thermal separation of power stage are required. |
Compared with TPS51200DRCR and ISL6264CRZ, the MAX1809ETI+ uniquely combines fully integrated bidirectional ±3A operation, internal switches, and simple RTOFF-based frequency tuning-making it optimal for space-constrained DDR termination where both sourcing and sinking are essential.
Availability
The MAX1809ETI+ is available at Aetrix Electronics and suitable for DDR memory termination, active bus termination, and low-dropout notebook power rails requiring stable component supply, long-term lifecycle support, and traceable sourcing.
Supply support for MAX1809ETI+ 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 applications.
The MAX1809ETI+ belongs to Maxim's high-efficiency DC-DC converter product line, designed specifically for active termination and dynamic voltage positioning in DDR memory subsystems of portable and embedded systems.
FAQ
What is the maximum continuous output current capability of the MAX1809ETI+?
The MAX1809ETI+ delivers ±3A continuous sourcing and sinking current. This bidirectional capability is confirmed in the datasheet's Absolute Maximum Ratings and Electrical Characteristics tables, where the current-limit threshold is specified as 3.3A to 4.9A depending on conditions, and typical operation supports stable ±3A across the full temperature range with appropriate thermal design.
Does the MAX1809ETI+ require an external Schottky diode?
No, the MAX1809ETI+ 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 associated with external diodes and enabling higher efficiency-especially critical in portable DDR termination applications.
How is the switching frequency set on the MAX1809ETI+?
The switching frequency of the MAX1809ETI+ is set by connecting a resistor (RTOFF) from the TOFF pin to GND. The off-time (tOFF) ranges from 0.24µs to 5.2µs depending on RTOFF (30.1kΩ to 499kΩ), and the resulting frequency is determined by input/output voltage and tOFF, reaching up to 1MHz. This is explicitly defined in the Electrical Characteristics table and Figure 4 of the datasheet.
What package type is used for the MAX1809ETI+?
The MAX1809ETI+ uses a 28-pin thin QFN package (5mm × 5mm, 0.5mm pitch) with an exposed backside thermal pad. This is confirmed in the Ordering Information table, which lists "MAX1809ETI" as "-40°C to +85°C / 28 Thin QFN", and the Pin Configurations diagram shows the top view layout matching this footprint.
Can the MAX1809ETI+ operate with a 3.3V input to generate a 1.25V DDR termination output?
Yes, the MAX1809ETI+ supports 3.3V input to generate 1.25V output. Its input range is 3.0V–5.5V and output is adjustable from 1.1V to VIN. The datasheet's Typical Operating Circuit (Figure 1) and Applications Information section explicitly cite VIN = 3.3V, VOUT = 1.25V operation with recommended L = 0.68µH and RTOFF = 73.2kΩ.
What is the purpose of the RDROOP resistor in MAX1809ETI+ applications?
The RDROOP resistor enables voltage positioning by introducing controlled output droop proportional to load current. As described in the Applications Information section, RDROOP × IOUT(MAX) ≤ VOUT(TYP) − VOUT(MIN) − (VRIPPLE/2), allowing reduced total output capacitance while maintaining transient response within tolerance-critical for DDR termination stability.
MAX1809ETI+ Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Series:
- -
- Package/Case:
- 28-WFQFN Exposed Pad
- Packaging:
- Bulk
- Product Status:
- Obsolete
- 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:
- 28-TQFN (5x5)
MAX1809ETI+ FAQ
1.How can I place an order for MAX1809ETI+ through Aetrix?
Please submit a Request for Quotation (RFQ) for MAX1809ETI+ 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 MAX1809ETI+ reliable?
The price and inventory of MAX1809ETI+ are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MAX1809ETI+ is usually 5 days.
3.What payment methods are accepted for MAX1809ETI+?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MAX1809ETI+ transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for MAX1809ETI+?
MAX1809ETI+ orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your MAX1809ETI+ 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 MAX1809ETI+?
For technical support, including MAX1809ETI+ datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MAX1809ETI+ requirements.
6.How does Aetrix verify that MAX1809ETI+ is sourced from the original manufacturer or authorized distributors?
All MAX1809ETI+ 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 MAX1809ETI+ meets industry standards.
7.What is the process for return or replacement of MAX1809ETI+?
All MAX1809ETI+ units undergo pre-shipment inspection (PSI). If there is an issue with MAX1809ETI+, 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 MAX1809ETI+ part is unused and in its original packaging.
Return procedure for MAX1809ETI+:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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