Renesas ISL5585AIMZ

Overview

ISL5585AIMZ from Intersil is a 3.3V industrial-grade ringing subscriber line interface circuit (SLIC) for voice-over-broadband systems, supporting balanced/unbalanced ringing up to 100V battery supply, 58dB longitudinal balance in forward active mode, and low standby power dissipation of 65mW at 75V - deployed in VoIP gateways and FTTH remote subscriber units.

For engineers reviewing the ISL5585AIMZ datasheet, ISL5585AIMZ pinout, ISL5585AIMZ application, or ISL5585AIMZ equivalent, key selection criteria include ringing battery voltage capability (100V), longitudinal balance grade (58dB), thermal shutdown alarm output, PLCC-28 package compatibility, and programmable transient current limit via external resistor.

Technical Context

The ISL5585AIMZ implements bipolar-DI process-based analog front-end architecture with dual high-voltage power amplifiers (TIP/RING), integrated DC loop feed control, and AC impedance synthesis using transmit/receive feedback paths. It supports seven operating modes-including balanced ringing, unbalanced ringing, forward/reverse active, tip open, and power denial-selected via TTL-compatible F2–F0 parallel interface.

Its supervisory logic includes switch hook detection (5–15mA programmable), ring trip comparator (1.12–1.37V threshold), ground key detection (fixed 12mA), and thermal alarm (175°C trip). The device uses external resistors for loop current limit (15–45mA), transient current limit (40–100mA), and polarity reversal timing, with CDC capacitor enabling DC loop current regulation.

Key Specifications

Pinout & Package

ISL5585AIMZ is housed in a 28-lead plastic leaded chip carrier (PLCC) per JEDEC standard N28.45, with Pb-free matte tin termination and 1.27mm lead pitch. The package supports reflow soldering per IPC/JEDEC J-STD-020C and features exposed substrate connection on Pin 27 (SCC) for thermal management in QFN variants - not applicable to PLCC version.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar ringing SLIC applications.

Compared with ISL5585BIMZ and ISL5585CIMZ, the ISL5585AIMZ delivers maximum loop reach (5,000 ft) and highest analog echo suppression (58dB), making it optimal for long-loop FTTH and outdoor RSU deployments where analog integrity is critical and digital compensation is unavailable.

Availability

ISL5585AIMZ is available at Aetrix Electronics and suitable for Voice over IP (VoIP) gateways, Fiber-to-the-Home (FTTH) remote terminals, and Ethernet terminal adapters requiring stable component supply across industrial temperature ranges and long product lifecycles.

Supply support for ISL5585AIMZ 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

Intersil Corporation (now part of Renesas Electronics) designs high-performance analog and mixed-signal ICs for communications, computing, and industrial markets, with emphasis on power efficiency and ruggedness.

The ISL5585 family targets voice-over-broadband infrastructure, delivering integrated SLIC functionality for short-to-medium loop POTS access in VoIP, DSL, and fiber-based CPE - optimized for low power, high ringing voltage, and robust fault tolerance.

FAQ

What is the maximum ringing battery voltage supported by the ISL5585AIMZ?

The ISL5585AIMZ supports a maximum high battery supply (VBH) of −100V, enabling open-circuit ringing voltages exceeding 67V_RMS in balanced mode. This 100V rating directly extends subscriber loop reach to 5,000 feet (≈1.5 km) and qualifies the ISL5585AIMZ for Fiber-in-the-Loop (FITL) and FTTH remote terminal applications where long-loop analog integrity is required.

How does the ISL5585AIMZ implement thermal protection?

The ISL5585AIMZ integrates a thermal shutdown circuit that triggers at approximately 175°C junction temperature, asserting the ALM pin low to signal fault condition. This feature disables internal power stages automatically, preventing permanent damage during sustained overcurrent or ambient overheating. The ALM output is TTL-compatible and can drive microcontroller interrupts or system-level fault logging without external level-shifting components.

What external components are required to configure loop current limit on the ISL5585AIMZ?

The ISL5585AIMZ requires a single external resistor (RIL) connected to the ILIM pin to set the DC loop current limit between 15mA and 45mA, calculated as RIL = 1760 / I_LIM (Ω). For example, a 25mA limit uses a 70.4kΩ resistor. This resistor directly programs the analog current regulator; no additional capacitors or op-amps are needed, minimizing BOM count and PCB area in space-constrained CPE designs.

Does the ISL5585AIMZ support both balanced and unbalanced ringing topologies?

Yes, the ISL5585AIMZ supports both balanced and unbalanced ringing via mode control inputs F2–F0. In balanced ringing (F2F1F0 = 100), differential gain is 80 V/V, delivering >67V_RMS open-circuit. In unbalanced mode (F2F1F0 = 010), gain is 40 V/V, yielding >33.5V_RMS - sufficient for legacy PBX interfaces. Both modes use the same VRS input and share identical thermal and electrical safety margins.

What is the significance of the 58dB longitudinal balance specification for the ISL5585AIMZ?

The 58dB longitudinal balance at 300Hz–1kHz ensures minimal common-mode signal coupling into the receive path, directly meeting Telcordia GR-902 and ITU-T G.961 echo return loss requirements. This high balance enables analog echo suppression below −24dB, reducing DSP processing load in VoIP gateways and allowing higher voice quality without complex adaptive algorithms - especially critical in multi-line systems with shared power supplies.