Microchip Technology LE57D111BTC

Overview

LE57D111BTC from Zarlink Semiconductor is a dual-channel Subscriber Line Interface Circuit (SLIC) designed for high-density POTS linecards, supporting Active/Reverse Polarity/Standby/Disconnect states, –39 to –58 V battery operation, on-chip thermal management, and programmable ring-trip detection. It integrates two SLIC channels in a single 44-pin eTQFP package for CO and DLC applications meeting China GF002-9002.1, Japan, Korea, Taiwan, and Australia requirements.

For engineers reviewing the LE57D111BTC datasheet, LE57D111BTC pinout, LE57D111BTC application, or LE57D111BTC equivalent, this page delivers verified electrical specs (e.g., ±150 mA output current, 80 dB crosstalk rejection, 26 dB 2-wire return loss), thermal management resistor interface (TMG1/TMG2), dual-channel supervision logic (DET1/DET2), and confirmed RoHS-compliant green eTQFP packaging - all validated against Zarlink Document ID# 081132, Rev. 5 (June 2011).

Technical Context

The LE57D111BTC implements two independent SLIC channels sharing a common +5 V (VCC) and negative battery (VBAT) supply, with separate TIP/RING power amplifiers (A1/B1, A2/B2), receive summing nodes (RSN1/RSN2), and transmit audio outputs (VTX1/VTX2). Each channel features TTL-compatible state control via C1i/C2i inputs and loop supervision via DETi outputs.

Its architecture includes on-chip thermal management (TMG1/TMG2 pins for external resistor-based power offloading), programmable DC feed current via IREF, dual-channel ring-trip detection using DAC/DB1/DB2 comparator inputs, and high-impedance analog ground (AGND/DGND) shared across both channels - enabling compact, low-component-count linecard designs compliant with international telephony standards.

Key Specifications

Pinout & Package

LE57D111BTC is housed in a 44-pin enhanced Thin Quad Flat Package (eTQFP) with exposed thermal pad connected to VBAT. The package meets RoHS Directive 2002/95/EC and supports lead-free reflow up to 245°C.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar dual-channel SLIC applications.

Compared with LE57D111DJC, LE57D111BTC offers superior thermal management (lower θJA) and RoHS compliance, while LE5712 extends operational range without altering interface or functionality - making LE57D111BTC the optimal balance of cost, compliance, and thermal performance for commercial linecard applications.

Availability

LE57D111BTC is available at Aetrix Electronics and suitable for Central Office linecards, Digital Loop Carrier systems, and multi-country POTS terminals requiring stable component supply, long-term lifecycle support, and RoHS-compliant manufacturing.

Supply support for LE57D111BTC 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

Zarlink Semiconductor Inc. was a fabless semiconductor company specializing in communications ICs, acquired by Microsemi in 2011. Its products targeted carrier-grade telephony, timing, and RF infrastructure.

The LE57D111BTC belongs to the VE580 Series dual-channel SLIC family, engineered specifically for high-density, low-power POTS linecards in central office and DLC applications - emphasizing thermal efficiency, international regulatory compliance, and reduced external component count.

FAQ

What is the maximum continuous output current per channel for the LE57D111BTC?

The LE57D111BTC supports ±150 mA continuous output current per channel (A1/B1 and A2/B2), verified per Absolute Maximum Ratings in Zarlink Document ID# 081132. This rating applies under VBAT = –58 V and TA ≤ 70°C with proper thermal management using external TMG resistors. Exceeding this current risks permanent damage or thermal shutdown.

Does the LE57D111BTC support reverse polarity mode, and how is it controlled?

Yes, the LE57D111BTC supports Reverse Polarity mode as one of its four defined control states. It is activated by setting C2i = 1 and C1i = 1 (per Table 6.14), reversing loop current direction to disable payphone keypads or meet specific country requirements. The mode maintains full supervision (DET output) and thermal management functionality.

How is loop current programmed on the LE57D111BTC, and what is the typical off-hook detection threshold?

Loop current is programmed via a single external resistor on the IREF pin, with RREF = 450 / ILOOP (e.g., 15 kΩ sets 30 mA). The off-hook detection threshold is typically 1/3 of the programmed loop current - so 30 mA yields ~10 mA threshold - confirmed in Section 6.14 and Figure 6.16 of the LE57D111BTC datasheet.

What is the purpose of the TMG1 and TMG2 pins on the LE57D111BTC?

The TMG1 and TMG2 pins on the LE57D111BTC provide dedicated thermal management outputs for each channel. Connecting external resistors (e.g., 1.6 kΩ) from TMG to VBAT diverts >50% of channel power dissipation away from the die, reducing junction temperature rise and enabling sustained operation at full load without heatsinks - a key feature validated in Application Note AN-VE580-TM.

Is the LE57D111BTC RoHS-compliant, and what does the 'BTC' suffix indicate?

Yes, the LE57D111BTC is RoHS-compliant: the 'BTC' suffix denotes the 44-pin eTQFP green package meeting EU Directive 2002/95/EC, using lead-free, halogen-free, and antimony-free materials with matte-tin plating. This is explicitly stated in the Ordering Information section of Zarlink Document ID# 081132.