Microchip Technology SY87700ALHG-TR

Overview

SY87700ALHG-TR from Micrel is a low-power, 3.3V AnyRate® clock and data recovery (CDR) IC supporting NRZ data rates from 32Mbps to 208Mbps. It performs full clock recovery and data retiming via dual on-chip PLLs-one for clock generation and one for clock recovery-and includes link fault detection. It is designed for SONET/SDH/ATM OC-1/OC-3 systems requiring precise jitter-tolerant timing alignment.

For engineers reviewing the SY87700ALHG-TR datasheet, SY87700ALHG-TR pinout, SY87700ALHG-TR application, or SY87700ALHG-TR equivalent, key selection criteria include its differential PECL I/O interface, industrial temperature range (–40°C to +85°C), dual-loop PLL architecture, 30% lower power versus SY87700V, and Pb-free 32-pin EPAD-TQFP (H32-1) packaging.

Technical Context

The SY87700ALHG-TR implements two independent PLLs: a receiver PLL synchronizes its VCO directly to incoming NRZ data (32–208Mbps), while a frequency-synthesis PLL generates output clocks using REFCLK as reference. Frequency selection is controlled by three TTL FREQSEL inputs, enabling eight discrete VCO center frequency ranges (e.g., 125–208MHz at 6× multiplication).

It supports differential PECL (ECL 100k) serial I/O with built-in line receivers, eliminating external buffering. Link fault detection monitors RDIN integrity and forces LFIN HIGH only when CD is HIGH and recovered clock deviation remains within ±1000ppm of REFCLK-derived frequency-ensuring robust lock status indication under signal loss or drift.

Key Specifications

Pinout & Package

SY87700ALHG-TR is packaged in a 32-pin EPAD-TQFP (H32-1) with exposed thermal pad soldered to PCB ground for enhanced thermal dissipation (θJA = 20.7°C/W at 500lfpm airflow). Pin functions are validated per Micrel's August 2009 datasheet (M9999-082009-D).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar clock and data recovery applications.

Compared with SY87701AL and ICS87200AMLF, the SY87700ALHG-TR provides optimized balance of integration (built-in PECL receiver), power efficiency (30% lower than SY87700V), and SONET-specific jitter performance - making it the preferred choice for OC-1/OC-3 line interface cards where reliability and minimal external components are critical.

Availability

SY87700ALHG-TR is available at Aetrix Electronics and suitable for SONET/SDH line interface cards, Fast Ethernet media converters, SMPTE 259M video transport systems, and proprietary high-speed serial links requiring stable component supply and long-term lifecycle support.

Supply support for SY87700ALHG-TR 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

Micrel, Inc. was a U.S.-based semiconductor company specializing in high-performance analog, RF, and timing solutions before its acquisition by Microchip Technology in 2015. Its timing products emphasized low-jitter, high-integration CDR and clock generation for telecom infrastructure.

The SY87700ALHG-TR belongs to Micrel's AnyRate® CDR product line, engineered specifically for SONET/SDH/ATM systems requiring flexible, low-power clock recovery across multiple data rates without changing hardware or layout.

FAQ

What is the maximum supported data rate for SY87700ALHG-TR?

The SY87700ALHG-TR supports NRZ data rates from 32Mbps up to 208Mbps. This range covers SONET OC-1 (51.84Mbps) and OC-3 (155.52Mbps) standards, with margin for implementation tolerances. The upper limit is defined by VCO center frequency (750–1250MHz) and loop filter bandwidth constraints documented in the August 2009 datasheet.

Does SY87700ALHG-TR require external loop filter components?

Yes, SY87700ALHG-TR requires external passive components on PLLRP/PLLRN (receiver PLL) and PLLSP/PLLSN (synthesis PLL) pins. Recommended values include 350Ω + 1.0µF (X7R) for the receiver loop and 680Ω + 1.0µF for the synthesizer loop. These set PLL bandwidth and jitter transfer characteristics per application requirements.

Is SY87700ALHG-TR pin-compatible with SY87700ALZG?

No, SY87700ALHG-TR (32-pin EPAD-TQFP, H32-1) is not pin-compatible with SY87700ALZG (28-pin SOIC, Z28-1). Pin counts, layouts, and thermal pad configuration differ significantly. Micrel explicitly states the 28-pin SOIC is "NOT recommended for new designs," confirming H32-1 as the intended platform for SY87700ALHG-TR.

What does the CD (Carrier Detect) pin do on SY87700ALHG-TR?

The CD pin on SY87700ALHG-TR controls receiver PLL operation: when HIGH, SY87700ALHG-TR performs normal clock recovery from RDIN; when LOW, it forces RDOUT and LFIN LOW and locks the receiver PLL to REFCLK. This enables graceful degradation during signal loss and supports carrier-sense protocols in optical modules.

Can SY87700ALHG-TR generate clocks independently of incoming data?

Yes, SY87700ALHG-TR can generate clocks independently using its frequency-synthesis PLL referenced to REFCLK. When CD is LOW or RDIN is absent, the receiver PLL falls back to REFCLK, and TCLK outputs reflect the synthesized frequency (determined by DIVSEL1/DIVSEL2 and REFCLK). This maintains clock continuity in loss-of-signal conditions.