Texas Instruments LMK61E0M-SIAT

Overview

LMK61E0M-SIAT from Texas Instruments is an ultra-low jitter (500-fs RMS typical), programmable 3.3-V LVCMOS oscillator with integrated fractional-N PLL, on-chip 50-MHz crystal, and EEPROM-based self-start capability. It delivers factory-programmed 70.656 MHz or user-configurable frequencies from 50 MHz to 200 MHz, supports glitchless ±1000 ppm frequency margining via I²C, and operates across –40°C to +85°C in a 7-mm × 5-mm QFM package - deployed in FPGA clocking, network line cards, and broadcast video timing.

For engineers reviewing the LMK61E0M-SIAT datasheet, LMK61E0M-SIAT pinout, LMK61E0M-SIAT application, or LMK61E0M-SIAT equivalent, this page provides verified technical context, validated pin functions, confirmed jitter and tolerance specs, real-world use cases in high-speed digital systems, and authoritative alternative part guidance for reference clock design.

Technical Context

The LMK61E0M integrates a 4.6–5.6 GHz LC VCO with fractional-N PLL architecture, using a 50-MHz internal crystal reference, programmable R-divider (×1/×4), and optional reference doubler to set PFD frequencies of 12.5 MHz or 100 MHz - enabling sub-1-ppb fine margining resolution or <5.2-ppb broadcast-optimized steps. Its dual-stage output divider (VCO post-divider ×4/×5 followed by integer divider 6–256) enables precise frequency synthesis without output glitches during reconfiguration.

Power conditioning uses isolated on-chip LDOs for analog (PLL/VCO) and digital (I²C/control logic) domains, suppressing supply noise coupling. The device boots autonomously from EEPROM, supports fast-mode I²C (up to 1000 kHz), and features tri-state-capable dual LVCMOS outputs (OUT0/OUT1) with individually configurable polarity, slew rate (0.2 ns or 1.1 ns rise/fall), and enable control via OE pin.

Key Specifications

Pinout & Package

LMK61E0M-SIAT is housed in a 7.00 mm × 5.00 mm, 8-pin QFM (SIA) package with exposed thermal pad. Pin numbering follows top-view layout: Pin 1 = OE, Pin 2 = ADD, Pin 3 = GND, Pin 4 = OUT0, Pin 5 = OUT1, Pin 6 = VDD, Pin 7 = SDA, Pin 8 = SCL.

Key Features

Applications

Equivalent & Alternatives

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

Compared with Si510-PROG, LMK61E0M-SIAT trades marginal jitter reduction for full integration and ease of use; compared with DS3231M, it delivers orders-of-magnitude better stability, programmability, and system-level timing control - making it the sole viable choice for FPGA, networking, and broadcast video reference clocking.

Availability

LMK61E0M-SIAT is available at Aetrix Electronics and suitable for network infrastructure, FPGA-based accelerators, broadcast video equipment, and medical imaging systems requiring stable component supply, long-term lifecycle assurance, and guaranteed traceable sourcing.

Supply support for LMK61E0M-SIAT 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

Texas Instruments is a global semiconductor leader specializing in analog, embedded processing, and clock solutions, with decades of expertise in high-performance timing devices and signal chain innovation.

The LMK61E0M belongs to TI's PLLatinum™ programmable oscillator family, designed specifically to replace discrete crystal oscillators and PLLs in high-speed digital systems where ultra-low jitter, field-programmability, and EEPROM-based reliability are mandatory.

FAQ

What is the default output frequency and how is it stored?

The LMK61E0M-SIAT powers up at 70.656 MHz, which is factory-programmed into its on-chip EEPROM. This value persists across power cycles and serves as the boot-time output unless overwritten via I²C. The EEPROM also stores register configurations including output enable state, divider settings, and margining offsets - eliminating need for host initialization.

Can both OUT0 and OUT1 be active simultaneously with different frequencies?

No - both outputs share the same PLL and output divider path, so they generate identical frequencies. However, they can be configured with opposite polarity (180° phase shift), same polarity (0°), or independently placed in high-impedance state. Frequency differentiation requires two separate LMK61E0M devices or a multi-output oscillator like the LMK04832.

Is external loop filter required for the PLL?

No - the LMK61E0M integrates a fully programmable passive loop filter (R2/C1/R3/C3) with fixed 10-nF C2. All filter components are on-die and configured via registers R36–R39. External filtering is unnecessary, simplifying layout and improving repeatability across manufacturing batches.

How does the ADD pin affect I²C communication?

The ADD pin sets the LSB of the 7-bit I²C slave address: tied to GND → 0x54, floating → 0x55, tied to VDD → 0x56. This allows up to three LMK61E0M devices on one I²C bus without address conflict. No pull-up/pull-down is required beyond these connections - the pin has no effect on oscillator operation itself.