Analog Devices Inc. LTC1706CS8-19#PBF

Overview

LTC1706CS8-19 from Analog Devices (formerly Linear Technology) is a precision VID voltage programmer IC designed to digitally set the output voltage of compatible 1.19V-reference DC/DC converters. It supports 1.3V–2.0V output in 50mV steps via four VID inputs, achieves ±0.25% output voltage accuracy, features built-in 40kΩ pull-up resistors with series diodes on all VID pins, and operates from 2.7V–5.5V VCC. It is used in Intel Mobile Pentium II processor power supplies.

For engineers reviewing the LTC1706CS8-19 datasheet, LTC1706CS8-19 pinout, LTC1706CS8-19 application, or LTC1706CS8-19 equivalent, key selection criteria include VID input threshold compatibility (VIL ≤ 0.4V, VIH ≥ 1.6V), R_FB1–SENSE resistance range (8–20kΩ), temperature-stable output error (±0.25% over –40°C to 85°C), and SO-8 package integration with synchronous buck controllers like LTC1435A and LTC1436.

Technical Context

The LTC1706CS8-19 implements a digitally controlled resistive ladder network that modifies the bottom feedback resistor (R_FB2) while keeping R_FB1 fixed at ~15kΩ between SENSE and FB. Its VID logic interprets binary codes (VID3–VID0) to generate precise 50mV voltage steps - grounding all four inputs yields 2.00V, while grounding only VID0 yields 1.30V.

Each VID pin integrates a 40kΩ pull-up resistor in series with a diode to VCC, enabling safe operation with input voltages up to 7V - exceeding VCC without clamping or damage. The device draws ultra-low supply current (0.1–5µA) when VID inputs are floating, rising predictably per grounded VID pin as (V_CC – 0.6V)/40kΩ.

Key Specifications

Pinout & Package

Package: 8-lead plastic SO (SO-8, narrow 0.150"), JEDEC MS-012, θ_JA = 120°C/W, T_JMAX = 110°C.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar VID voltage programming applications.

Compared with LTC1706IS8-19, the LTC1706CS8-19 offers lower cost and sufficient thermal margin for consumer notebooks, while TPS51100PWR shifts architecture toward integrated LDO+translator but forfeits the self-contained, resistor-ladder simplicity and Intel Mobile VID compliance of the LTC1706CS8-19.

Availability

LTC1706CS8-19 is available at Aetrix Electronics and suitable for Intel Mobile Pentium II power supplies, notebook computer core regulators, and palmtop/PDA system power requiring stable component supply, long-term lifecycle support, and SO-8 package compatibility.

Supply support for LTC1706CS8-19 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 and maintains its precision analog and power management product lines. Linear Technology was founded in 1981 and specialized in high-performance linear ICs, switching regulators, and data conversion solutions.

The LTC1706CS8-19 belongs to Linear Technology's VID-programmable voltage control family, designed specifically to enable compliant, accurate, and compact core voltage regulation for Intel Mobile Pentium II and compatible microprocessors in portable computing platforms.

FAQ

What is the primary function of the LTC1706CS8-19?

The LTC1706CS8-19 is a precision VID voltage programmer IC that sets the output voltage of compatible 1.19V-reference DC/DC converters (e.g., LTC1435A) from 1.3V to 2.0V in 50mV steps using four digital VID inputs. It replaces manual resistor networks with an integrated, temperature-stable resistive ladder, ensuring ±0.25% accuracy and full Intel Mobile VID compliance - critical for stable CPU core voltage regulation in notebooks and palmtops.

Does the LTC1706CS8-19 require external components to operate?

The LTC1706CS8-19 operates autonomously with only VCC decoupling (≥0.1µF ceramic) and VID input connections - no external resistors, capacitors, or DACs are needed. Its built-in 40kΩ pull-up resistors with series diodes eliminate external bias networks, and the fixed R_FB1–SENSE path (8–20kΩ) interfaces directly with the regulator's FB and SENSE pins. This makes the LTC1706CS8-19 a complete, self-contained VID programming solution.

Can the LTC1706CS8-19 be used with non-Linear Technology regulators?

The LTC1706CS8-19 is explicitly designed for Linear Technology DC/DC converters with a 1.19V internal reference (e.g., LTC1433, LTC1435A, LTC1436). While it may function with other 1.19V-reference regulators, compatibility is not guaranteed - feedback impedance, sensing topology, and transient response must match. For example, when used with LT1575-ADJ (1.21V reference), the output range shifts to 1.27V–2.03V in 50.8mV steps, deviating from Intel VID spec. Always verify reference voltage and FB node behavior before substitution.

What is the maximum allowable voltage on the VID pins of the LTC1706CS8-19?

The VID pins of the LTC1706CS8-19 tolerate up to 7V absolute maximum, independent of VCC, due to internal series diodes between each 40kΩ pull-up resistor and VCC. This allows safe interfacing with 5V logic signals even when VCC is 3.3V - a key design feature enabling mixed-voltage system integration without level shifters. Exceeding 7V risks permanent damage, and input voltage must remain within –0.3V to 7V per Absolute Maximum Ratings.

How does temperature affect the output voltage accuracy of the LTC1706CS8-19?

The LTC1706CS8-19 maintains ±0.25% output voltage accuracy across its full specified operating temperature range of 0°C to 70°C - this is a guaranteed parameter (denoted by "G" in the datasheet), not just a typical value. Graphs show error remains within ±0.25% from –50°C to +100°C, confirming robust thermal performance. This stability eliminates need for external temperature compensation in commercial portable applications where ambient rarely exceeds 70°C.