Analog Devices Inc. LTC3718EG#PBF

Overview

LTC3718EG#PBF from Analog Devices (formerly Linear Technology) is a dual-output synchronous DC/DC controller optimized for DDR/QDR memory termination, operating from 1.5V input and delivering regulated output at 0.5×VIN with ±10A sourcing/sinking capability. It integrates a buck regulator with valley current mode control and an internal 1.4MHz boost converter to generate 5V INTVCC, eliminating external auxiliary supplies. Used in server memory subsystems requiring fast transient response and precise VTT tracking.

For engineers reviewing the LTC3718EG#PBF datasheet, LTC3718EG#PBF pinout, LTC3718EG#PBF application, or LTC3718EG#PBF equivalent, key selection criteria include its 24-lead SSOP package, true current-mode architecture with no sense resistor required, symmetrical source/sink current limiting, programmable soft-start, and integrated overvoltage/undervoltage protection on the buck output.

Technical Context

The LTC3718EG#PBF implements valley current mode control using an external MOSFET's R_DS(ON) for sensing-no sense resistor needed-and employs a one-shot timer with ION/VON inputs to set minimum on-time (<100ns) and maintain stable switching frequency across input and load variations. Its dual-regulator architecture combines a high-current buck stage (VIN1 ≥1.5V, VOUT = 0.5×VIN) with an independent boost converter (VIN2 = 1.5–10V, fBOOST = 0.9–1.9MHz) powering the 5V INTVCC rail.

Control logic includes OPTI-LOOP® compensation for wide-load transient optimization, symmetrical current limit thresholds for bidirectional termination, and dedicated PGOOD monitoring with ±10% hysteresis. Fault protection comprises foldback current limiting, output overvoltage shutdown, and optional short-circuit timer-enabling robust operation in high-density memory bus environments.

Key Specifications

Pinout & Package

24-lead plastic SSOP (G package), 0.635mm pitch, exposed thermal pad connected to PGND pins (14, 19) for enhanced power dissipation.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar DDR/QDR memory termination applications.

Compared with LTC3717EG#PBF and TPS51220ARUKT, the LTC3718EG#PBF uniquely integrates a 1.4MHz boost converter to generate INTVCC, supports higher ±10A bidirectional current, and operates down to 1.5V input-making it the only option capable of fully self-contained, high-current DDR/QDR termination without auxiliary supplies.

Availability

LTC3718EG#PBF is available at Aetrix Electronics and suitable for DDR memory termination, QDR RAM bus regulation, and SSTL/HSTL level translation requiring stable component supply, long-term lifecycle support, and guaranteed industrial temperature performance.

Supply support for LTC3718EG#PBF 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

Analog Devices (acquired Linear Technology in 2017) is a global leader in high-performance analog, mixed-signal, and power management ICs, serving precision instrumentation, communications, and computing markets.

The LTC3718EG#PBF belongs to Linear's high-efficiency DC/DC controller product line, designed specifically for demanding memory interface power applications including DDR, QDR, and advanced bus termination where accuracy, speed, and integration are critical.

FAQ

What is the minimum input voltage supported by the LTC3718EG#PBF?

The LTC3718EG#PBF supports a minimum input voltage of 1.5V on VIN1, enabling direct regulation from low-voltage system rails such as 1.8V or 2.5V DDR supply domains. This specification is guaranteed over the full –40°C to +85°C operating temperature range and allows the LTC3718EG#PBF to operate efficiently in modern memory subsystems where input voltage headroom is constrained.

Does the LTC3718EG#PBF require an external sense resistor for current monitoring?

No, the LTC3718EG#PBF does not require an external sense resistor. It uses the R_DS(ON) of the external bottom N-channel MOSFET as the current sensing element-measuring voltage between SENSE+ and SENSE– pins. This architecture reduces BOM cost, PCB area, and conduction losses. The VRNG pin allows scaling of the sense threshold from 50mV to 200mV to accommodate MOSFET on-resistance variation.

How does the LTC3718EG#PBF achieve stable switching frequency across varying input voltages?

The LTC3718EG#PBF achieves stable switching frequency using a one-shot timer whose on-time is set by the ION pin current and VON pin voltage. Connecting a resistor from VIN to ION yields an on-time inversely proportional to VIN, resulting in approximately constant frequency operation. For tighter regulation, tie VON to VOUT-this compensates for output voltage changes and maintains frequency stability across load and line variations.

What is the role of the integrated boost converter in the LTC3718EG#PBF?

The integrated boost converter in the LTC3718EG#PBF generates a regulated 5V supply (INTVCC) from VIN2 (1.5–10V) to power the gate drivers and internal control circuitry. Operating at 0.9–1.9MHz, it eliminates the need for an external 5V auxiliary supply-reducing system complexity, component count, and board space. The VFB2 pin allows precise setting of INTVCC via an external resistor divider.

Can the LTC3718EG#PBF support bidirectional current flow for DDR/QDR termination?

Yes, the LTC3718EG#PBF supports symmetrical sourcing and sinking up to ±10A, essential for DDR/QDR memory bus termination. Its valley current mode architecture includes independent positive and negative current sense thresholds-programmable via the VRNG pin-to ensure precise bidirectional current limiting. This enables accurate VTT regulation during both read and write cycles without polarity-dependent performance degradation.