Infineon Technologies BB555H7912XTSA1

Overview

BB555H7912XTSA1 from Infineon Technologies is a silicon tuning diode (varactor) designed for UHF-TV tuner front-end voltage-controlled oscillator (VCO) and RF filter tuning circuits. It delivers a capacitance of 18.7 pF at 1 V, 2.1 pF at 28 V, 9.8:1 capacitance ratio (CT₁/CT₂₈), 0.6 nH series inductance, and 0.75 Ω series resistance at 470 MHz - enabling precise, low-loss frequency synthesis in broadcast receiver modules.

For engineers reviewing the BB555H7912XTSA1 datasheet, BB555H7912XTSA1 pinout, BB555H7912XTSA1 application, or BB555H7912XTSA1 equivalent, key selection criteria include its SC79 package footprint, tight capacitance matching (±1% across 4-diode sequence), low-temperature coefficient (−5×10⁻⁴ /°C at 1 V), RoHS-compliant Pb-free construction, and specified operation up to +150°C ambient.

Technical Context

This varactor operates as a voltage-dependent capacitor in reverse-biased mode, where applied DC tuning voltage (1–28 V) linearly modulates junction capacitance via depletion width control. Its low LS (0.6 nH) and rS (typ. 0.58 Ω) minimize parasitic resonance and insertion loss in UHF band (300–900 MHz) tank circuits.

The device uses an "in-line" matching assembly process ensuring ±1% capacitance uniformity across production lots - critical for multi-stage VCOs requiring phase coherence and minimal calibration drift over temperature (−55°C to +150°C).

Key Specifications

Pinout & Package

SC79 ultra-small surface-mount plastic package (1.3 mm × 0.7 mm × 0.5 mm), cathode-marked with laser dot on top surface; single-anode, single-cathode configuration optimized for high-density RF layout.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar varactor diode applications.

Compared with BAT54C and SMV1232, BB555H7912XTSA1 uniquely balances UHF-specific low LS, production-grade matching, and extended temperature capability - making it the only option qualified for legacy analog/digital TV tuner replacement programs requiring drop-in compatibility and long-lifecycle support.

Availability

BB555H7912XTSA1 is available at Aetrix Electronics and suitable for UHF-TV tuners, digital terrestrial television (DTT) front-ends, and automotive DAB+ radio modules requiring stable component supply, long-term obsolescence management, and traceable RoHS-compliant sourcing.

Supply support for BB555H7912XTSA1 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

Infineon Technologies is a German semiconductor manufacturer specializing in power management, RF, and automotive ICs, with leadership in high-reliability discrete components for broadcast and mobility markets.

BB555H7912XTSA1 belongs to Infineon's BB5xx silicon tuning diode product line, engineered specifically for high-volume UHF TV and digital radio tuner applications demanding precision capacitance control, thermal stability, and manufacturing scalability.

FAQ

What is the maximum reverse voltage rating for BB555H7912XTSA1?

The absolute maximum reverse voltage (VR) is 30 V at TA = 25°C, with a peak reverse voltage (VRM) of 35 V for short-duration pulses. Operation beyond 30 V DC risks irreversible junction breakdown and permanent capacitance shift, especially above 85°C ambient where IR increases significantly.

Does BB555H7912XTSA1 require external biasing circuitry?

Yes - it must be reverse-biased via a high-impedance DC voltage source (typically 1–28 V) in series with an RF choke or high-value resistor (>100 kΩ). No AC coupling is needed since the diode operates solely in reverse mode; forward conduction must be avoided to prevent damage and capacitance nonlinearity.

How does temperature affect capacitance stability in BB555H7912XTSA1?

Capacitance exhibits a negative temperature coefficient: −5×10⁻⁴ /°C at 1 V, −3×10⁻⁴ /°C at 25 V. At 1 V bias, C drops ~0.5% per 10°C rise; this is fully characterized and compensated in Infineon's tuner reference designs using dual-diode configurations and lookup-table calibration.

Is BB555H7912XTSA1 compatible with lead-free reflow profiles?

Yes - the SC79 package is qualified for standard JEDEC J-STD-020D lead-free reflow, with peak temperature up to 260°C for 30 seconds. The die attach and molding compound are fully compliant; no special prebake or nitrogen atmosphere is required for assembly yield.