Analog Devices Inc. AD809BR

Overview

AD809BR from Analog Devices is a 155.52 MHz frequency synthesizer IC that generates ECL/PECL-compatible output clocks from 19.44 MHz or 9.72 MHz TTL/CMOS/PECL reference inputs. It integrates a low-jitter VCO, phase-frequency detector, loop filter, and input multiplexer in a single 16-pin SOIC package, and is used to generate transmit bit clocks in SONET/SDH optical line cards.

For engineers reviewing the AD809BR datasheet, AD809BR pinout, AD809BR application, or AD809BR equivalent, key selection criteria include its ±2.0° RMS output jitter at 155.52 MHz, dual-input mux for loop-timed recovery, single +5 V or –5.2 V supply operation, and guaranteed low-drift behavior during input loss.

Technical Context

The AD809BR implements a second-order PLL with auto-select ×8 or ×16 integer frequency multiplication, supporting both differential PECL (Pins 12/13) and single-ended TTL/CMOS (Pin 10) reference inputs via an internal MUX controlled by Pin 15. Its on-chip VCO operates without external tuning components, while loop damping is externally adjustable via two capacitor terminals (Pins 7/8).

Output stage delivers complementary 155.52 MHz PECL signals (Pins 4/5) with 1.1–1.5 ns rise/fall times, 46–62% symmetry, and output voltage levels referenced to VCC (VOH = –1.2 to –0.7 V, VOL = –2.0 to –1.7 V). The device guarantees capture/tracking ranges of ±20 kHz around 19.44 MHz (×8) or ±10 kHz around 9.72 MHz (×16).

Key Specifications

Pinout & Package

AD809BR is housed in a 16-pin narrow-body SOIC (R-16A) package measuring 0.157" × 0.244" (4.00 mm × 6.20 mm), with 0.050" lead pitch and gull-wing leads. Thermal resistance θ_JA = 110°C/W.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar frequency synthesizer applications.

Compared with AD809BR, AD9510BCPZ offers greater flexibility but adds complexity and power; ICS8430AYI-01LFT simplifies BOM with integrated crystal but sacrifices input versatility and failsafe behavior - AD809BR remains optimal for robust, mux-enabled SONET/SDH bit clock generation.

Availability

AD809BR is available at Aetrix Electronics and suitable for SONET OC-3 line cards, SDH STM-1 add-drop multiplexers, and Fiber-in-the-Loop terminal equipment requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for AD809BR 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 is a global leader in high-performance analog, mixed-signal, and digital signal processing semiconductors, serving precision instrumentation, communications, and industrial markets since 1965.

The AD809BR belongs to Analog Devices' timing and clock generation product line, designed specifically for telecom infrastructure applications requiring low-jitter, fail-safe, and input-flexible frequency synthesis at OC-3/STM-1 rates.

FAQ

What is the primary function of the AD809BR in telecom timing systems?

The AD809BR functions as a dedicated 155.52 MHz frequency synthesizer that converts 19.44 MHz or 9.72 MHz reference inputs into a low-jitter PECL clock output. In telecom systems, it serves as the transmit bit clock generator for SONET OC-3 and SDH STM-1 interfaces. Its auto-select ×8/×16 multiplication, input mux, and guaranteed low-drift behavior make AD809BR especially suited for line cards where reliability under reference loss is critical.

Does the AD809BR support both single-ended and differential reference inputs?

Yes, the AD809BR supports both configurations via an internal multiplexer. A TTL/CMOS reference is applied to Pin 10 (TTL/CMOSIN), while differential PECL references connect to Pins 12 and 13 (CLKIN/CLKINN). Pin 15 (MUX) controls selection: logic low chooses Pin 10; logic high chooses Pins 12/13. This dual-input capability enables AD809BR to operate in either local oscillator or recovered-data timing architectures without hardware change.

What is the significance of the AD809BR's guaranteed low-drift behavior during input loss?

The AD809BR is designed to drift low by approximately 20% in output frequency when no valid input signal is present - a deterministic fail-safe response. This prevents metastable locking or uncontrolled frequency excursions that could disrupt downstream serializers or cause frame loss. For systems relying on AD809BR as a critical timing source, this behavior enables predictable fault handling and supports graceful degradation strategies in SONET/SDH network elements.

How does the AD809BR achieve low output jitter without external VCO components?

The AD809BR integrates a fully self-contained, low-noise VCO optimized for 155.52 MHz operation, eliminating the need for external inductors, varactors, or tuning diodes. Jitter performance (2.0° RMS typical) is achieved through matched on-die components, careful layout isolation between analog and digital sections, and precise control of loop dynamics via external damping capacitors (Pins 7/8). This monolithic integration ensures consistent jitter behavior across temperature and supply voltage variations in AD809BR deployments.

Can the AD809BR be used with a +3.3 V supply?

No, the AD809BR is specified only for +5 V or –5.2 V single-supply operation, as confirmed by Absolute Maximum Ratings (supply voltage up to +12 V) and operating specifications (V_MIN = 4.5 V, V_MAX = 5.5 V). Its PECL output stage and internal logic are designed for 5 V rail compatibility. Using +3.3 V would result in invalid output voltage levels, insufficient drive strength, and potential functional failure - AD809BR must be powered per its published supply requirements.