Microchip Technology LE75183CDSC

Overview

LE75183CDSC from Zarlink Semiconductor is a monolithic Line Card Access Switch (LCAS) providing solid-state equivalent functionality of three 2-form-C electromechanical relays. It delivers power ringing access, line test-out (loop access), SLIC test-in, and ringing generator test access for analog telephony line cards. Key confirmed parameters: 5 V only supply, 20-pin SOIC (GULL) package, ≤1.1 mA typical IDD in all-OFF state, >480 V breakdown rating on ringing access switch (SW8), and integrated thermal shutdown with battery-monitoring all-OFF fail-safe.

For engineers reviewing the LE75183CDSC datasheet, LE75183CDSC pinout, LE75183CDSC application, or LE75183CDSC equivalent, this page provides verified switching states, isolation ratings, ON-resistance matching (≤1.0 Ω), protection architecture (diode bridge/SCR + current limiting), and Telcordia TR-57-compliant 8-state operation - critical for central office, DLC, and HFC/FITL line card design.

Technical Context

The LE75183CDSC implements eight independently controlled solid-state switches (SW1–SW8) with break-before-make or make-before-break operation, driven by TTL-compatible logic inputs (INRING, INTESTin, INTESTout, LATCH) with internal 75 kΩ pull-up/down resistors. Its control logic supports eight distinct operational states including simultaneous test-out and ring-test - a feature exclusive to the C-version per datasheet Section 1.0.

Protection architecture differs by variant: LE75183C integrates diode bridge/SCR clamping, current limiting, and thermal shutdown (Figure 1), enabling bidirectional fault steering to ground. It uses VBAT (−72 V to −19 V) solely as a reference for protection circuitry and enters all-OFF state upon battery loss - a hardwired safety behavior confirmed in Section 1.0 and Table 5.2.

Key Specifications

Pinout & Package

LE75183CDSC is housed in a 20-pin plastic SOIC (GULL) package per Ordering Information and Figure 6. Pin functions are validated from Section 3.1 "Pin Descriptions" and the 20-pin SOIC connection diagram (page 6).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar line card access switch applications.

Compared with LE75183ADSC and LE75183BDSC, the LE75183CDSC uniquely delivers Telcordia TR-57-compliant 8-state operation and full diode/SCR fault clamping - making it the sole option for new DLC and HFC/FITL deployments requiring simultaneous test access and ringing generator validation.

Availability

LE75183CDSC is available at Aetrix Electronics and suitable for central office, digital loop carrier, and HFC/FITL analog line card applications requiring stable component supply, long lifecycle support, and RoHS-compliant green packaging.

Supply support for LE75183CDSC 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 was a fabless semiconductor company specializing in communications ICs, acquired by Microsemi in 2011. It pioneered high-reliability analog front-end solutions for telephony infrastructure.

The LE75183CDSC belongs to the VoiceEdge™ VE750 series Line Card Access Switches, designed specifically to replace electromechanical relays in analog telephony line cards while meeting Telcordia, ITU-T, and FCC protection standards.

FAQ

What is the function of the TSD pin on the LE75183CDSC?

The TSD pin on the LE75183CDSC serves as both an input and output for thermal shutdown control. As an output, it reads LOW when the device enters thermal shutdown mode - providing direct system-level fault indication. As an input, tying it HIGH disables the thermal shutdown mechanism (though this is not recommended per datasheet Section 3.1). This dual-role pin enables flexible integration into line card monitoring systems without additional sensors.

Does the LE75183CDSC require external driver circuitry for its logic inputs?

No, the LE75183CDSC does not require external driver circuitry. Its logic inputs - INRING (75 kΩ pull-up), INTESTin (75 kΩ pull-down), INTESTout (75 kΩ pull-up), and LATCH (75 kΩ pull-down) - include internal bias resistors. This allows direct connection to TTL- or CMOS-level controllers, reducing BOM count and layout complexity while ensuring defined power-up states.

How does the LE75183CDSC respond to loss of battery voltage?

The LE75183CDSC monitors VBAT solely as a reference for its protection circuitry. When VBAT drops below approximately −15 V, the device automatically enters an all-OFF state and remains there until VBAT rises above −10 V. This fail-safe behavior, documented in Section 1.0 and Table 5.2, prevents unsafe line states during battery brownout or disconnect in remote power applications like DAML or FITL.

What distinguishes the LE75183CDSC from the LE75183ADSC and LE75183BDSC variants?

The LE75183CDSC adds an eighth operational state - simultaneous test-out and ring-test - required for Telcordia TR-57 compliance in DLC systems. It also includes full diode bridge/SCR clamping (vs. diode-only in B-version), enabling bidirectional fault steering. Unlike the A- and B-versions, the C-version's protection and state logic are explicitly validated for TR-57 applications per Section 1.0.

What is the maximum allowable OFF-state voltage across the LE75183CDSC ringing access switch (SW8)?

The LE75183CDSC ringing access switch (SW8) has a pole-to-pole isolation rating of >480 V, as specified in Section 1.0 and Absolute Maximum Ratings. This rating allows the switch to safely withstand transient overvoltages during ringing cadence or fault conditions - provided appropriate secondary protection (e.g., foldback-type protector) is used to limit tip/ring terminal voltage below the 480 V threshold.