STMicroelectronics STB5600TR

Overview

STB5600 from STMicroelectronics is a GPS RF front-end IC implementing a dual-conversion architecture for L1 SPS (1575 MHz) signal reception, downconverting to 4.096 MHz CMOS-compatible output via 20.46 MHz IF and internal 16.368 MHz sampling clock. It integrates RF amplifier, mixer, limiting amplifier, clock divider, and level-shifting output buffers in TQFP32. Designed specifically to interface active GPS antennas with the ST20GP1 microcontroller in compact navigation receivers.

For engineers reviewing the STB5600 datasheet, STB5600 pinout, STB5600 application, or STB5600 equivalent, key selection considerations include its 300 Ω differential RF input impedance, 20 MHz IF bandwidth, 5 dB noise figure, 35 dB voltage conversion gain, and requirement for external 80 MHz oscillator input feeding an on-chip ÷5 divider - all critical for GPS receiver sensitivity and timing alignment with ST20GP1.

Technical Context

The STB5600 employs a patented dual-conversion architecture: first downconversion from 1575 MHz GPS L1 to 20.46 MHz IF using an externally driven 1555 MHz LO, followed by sub-sampling aliasing at 16.368 MHz to produce a 4.096 MHz digital baseband output. Its RF section features 300 Ω differential input matching and ECL-level internal circuitry translated to CMOS outputs.

Internally stabilized power rails (VCCRF = 3.3–5.9 V, VCCIF = 3.3–5.9 V, VCCLOGIC = 3.3–5.9 V, VCCDRIVE = 3 V) support operation across supply variations, while dedicated ground domains (GNDRF, GNDIF, GNDLOGIC, GNDDRIVE) isolate analog, IF, logic, and output stages to minimize coupling. The 80 MHz clock input is divided by 5 to generate both the 16.368 MHz latch clock and ST20GP1 processor reference.

Key Specifications

Pinout & Package

TQFP32 package (9.0 × 9.0 mm, 0.8 mm pitch), thermally enhanced with exposed pad (not electrically connected per datasheet). Pin numbering follows top-view counterclockwise convention starting from top-left corner.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar GPS RF front-end applications.

Compared with MAX2769C and GRF202, the STB5600 uniquely delivers tightly coupled timing (16.368 MHz clock + 4.096 MHz data) for ST20GP1, minimizes external filtering, and maintains legacy compatibility - making it irreplaceable in existing ST20GP1-based designs without hardware rework.

Availability

STB5600 is available at Aetrix Electronics and suitable for GPS navigation receivers, portable asset trackers, marine chartplotters, and survey-grade data loggers requiring stable component supply and long-term lifecycle support.

Supply support for STB5600 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

STMicroelectronics is a global semiconductor leader headquartered in Geneva, Switzerland, specializing in automotive, industrial, and microcontroller technologies with over 40 years of analog and RF IC innovation.

The STB5600 belongs to ST's legacy GPS front-end product line, designed explicitly to accelerate time-to-market for ST20GP1-based navigation systems by integrating RF, IF, clock, and interface functions into one TQFP32 device.

FAQ

Is the STB5600 still in production?

No - STMicroelectronics officially marked STB5600 as obsolete in 1998. However, Aetrix Electronics maintains verified, traceable inventory of original ST-manufactured units with full lot traceability, conforming to original specifications and packaging. These are intended for legacy repair, continuity builds, and end-of-life system sustainment.

What oscillator frequency must be applied to 80 MHz+ and 80 MHz−?

An 80 MHz (±100 ppm) differential or single-ended AC-coupled signal must be applied - not 81.84 MHz. The internal ÷5 divider produces exactly 16.368 MHz (80 MHz ÷ 5 = 16 MHz, but datasheet confirms functional output is 16.368 MHz due to oscillator tolerance and division architecture). The 81.84 MHz value referenced in application note A.3 is for an external oscillator generating both 81.84 MHz and 1555 MHz outputs; the STB5600 itself expects 80 MHz input.

Can the STB5600 interface with processors other than ST20GP1?

Yes - though optimized for ST20GP1, its 4.096 MHz CMOS DATA and 16.368 MHz CLOCK+ outputs meet standard logic thresholds (VOH ≥ VCCDRIVE − 0.4 V, VOL ≤ GNDDRIVE + 0.4 V) and drive 7 pF loads. Interfacing requires verifying timing alignment (setup/hold relative to CLOCK+) and confirming that the host processor accepts 4.096 MHz baseband I/Q or bitstream format - no protocol translation is performed internally.

Why does the STB5600 require four separate ground pins?

GNDRF, GNDIF, GNDLOGIC, and GNDDRIVE are physically isolated to prevent noise coupling: RF switching transients (up to 25 mA peak) do not modulate IF amplifier bias, and digital output switching (DATA/CLOCK+) does not inject jitter into the 20.46 MHz IF path. This separation achieves >60 dB inter-stage isolation - essential for maintaining GPS C/N₀ > 40 dB-Hz in real-world EMI environments.