Analog Devices Inc. LTC6903HMS8#PBF

Overview

LTC6903HMS8#PBF from Analog Devices (formerly Linear Technology) is a serial-port programmable silicon oscillator IC delivering precision square-wave clock outputs from 1kHz to 68MHz. It features SPI-compatible control, 0.5% typical initial frequency accuracy, 10ppm/°C temperature drift, and operates from a single 2.7V–5.5V supply in industrial and extended-temperature systems.

For engineers reviewing the LTC6903HMS8#PBF datasheet, LTC6903HMS8#PBF pinout, LTC6903HMS8#PBF application, or LTC6903HMS8#PBF equivalent, key selection criteria include its MS8 package, –40°C to 125°C operating range, 1.7mA typical supply current below 1MHz, output enable (OE) functionality, and deterministic jitter performance under 0.4% from 1kHz to 8MHz.

Technical Context

The LTC6903HMS8#PBF integrates a high-frequency VCO (34–68MHz) with a proprietary feedback loop that linearizes digital-to-frequency mapping via a 10-bit DAC and 4-bit OCT divider. Its frequency is set by the equation f = 2078 × 2^(OCT−10) × DAC / 1024 Hz, enabling monotonic, 0.1% resolution tuning across 17 octaves.

It uses an SPI-compatible 16-bit serial interface with SEN/SDI/SCK pins, supports asynchronous output enable (OE), and provides two complementary CMOS clock outputs (CLK/CLK) configurable via CNF[1:0] bits. Internal power conservation circuitry limits settling time to ≤100µs during DAC-only updates.

Key Specifications

Pinout & Package

Package: 8-lead plastic MSOP (MS8), 3.0mm × 3.0mm body, 0.65mm pitch, –40°C to 125°C operating range.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar digitally programmable oscillator applications.

Compared with LTC6904HMS8#PBF, the LTC6903HMS8#PBF offers faster SPI configuration (20MHz vs 100kHz I²C) and deterministic latency, while LTC1799CS6#TRMPBF trades programmability for lower cost and smaller footprint-making it viable only in fixed-frequency, high-volume consumer applications.

Availability

LTC6903HMS8#PBF is available at Aetrix Electronics and suitable for industrial motor control, automotive powertrain diagnostics, and aerospace telemetry systems requiring stable component supply across extended temperature ranges.

Supply support for LTC6903HMS8#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, Inc. (acquired Linear Technology in 2017) is a global leader in high-performance analog, mixed-signal, and digital signal processing semiconductors.

The LTC6903 belongs to Linear's precision timing product line, designed specifically for applications demanding digitally programmable, temperature-stable clock sources without external crystals or complex PLL design.

FAQ

What is the operating temperature range guaranteed for the LTC6903HMS8#PBF?

The LTC6903HMS8#PBF is specified and tested over –40°C to 125°C, with full electrical performance guaranteed across this extended industrial temperature range. This differs from the CMS8 grade (0°C to 70°C) and IMS8 grade (–40°C to 85°C), making the HMS8 variant suitable for under-hood automotive and high-ambient industrial environments where the LTC6903HMS8#PBF must maintain 0.5% frequency accuracy without derating.

Does the LTC6903HMS8#PBF require external passive components to operate?

No, the LTC6903HMS8#PBF requires only a single 0.1µF ceramic bypass capacitor between V+ and GND, placed within 2mm of the pins. Unlike crystal oscillators or PLL-based solutions, it needs no external resistors, capacitors, inductors, or crystals-enabling true "single-chip" clock generation. The LTC6903HMS8#PBF integrates all timing elements internally, including the master oscillator, DAC, divider, and output buffers.

How does the LTC6903HMS8#PBF achieve 0.1% frequency resolution?

The LTC6903HMS8#PBF achieves 0.1% resolution through a dual-stage digital control architecture: a 4-bit OCT register selects one of 16 octave bands (each doubling frequency range), and a 10-bit DAC fine-tunes within that band using the equation f = 2078 × 2^(OCT−10) × DAC / 1024 Hz. This structure ensures monotonic step response and eliminates gaps or overlaps across the full 1kHz–68MHz span-verified in the LTC6903HMS8#PBF's integral nonlinearity plot (<1 LSB).

Can both CLK outputs of the LTC6903HMS8#PBF be disabled simultaneously?

Yes, the LTC6903HMS8#PBF supports simultaneous disable of both CLK outputs via the CNF[1:0] register bits: setting CNF1=CNF0=1 places the device in low-power powered-down mode, reducing supply current significantly. Alternatively, asserting OE (Pin 7) forces both outputs LOW asynchronously-useful for rapid clock gating during sleep modes. Both methods are documented in the LTC6903HMS8#PBF's Output Configuration Table 2 and preserve register state.

What is the maximum clock frequency supported by the SPI interface of the LTC6903HMS8#PBF?

The SPI interface of the LTC6903HMS8#PBF supports a maximum SCK frequency of 20MHz across the full –40°C to 125°C operating range, as specified in the Absolute Maximum Ratings and Timing Characteristics tables. This allows full 16-bit register updates in under 1µs, enabling real-time frequency reprogramming in closed-loop systems such as adaptive clock recovery circuits-without impacting the LTC6903HMS8#PBF's core timing accuracy or jitter performance.