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Microchip Technology LE79R70-1DJCT
- Part No.:
- LE79R70-1DJCT
- Manufacturer:
- Microchip Technology
- Category:
- Telecom
- Package:
- 32-LCC (J-Lead)
- Datasheet:
-
LE79R70-1DJCT.pdf
- Description:
- IC TELECOM INTERFACE 32PLCC
- Quantity:
- Payment:
- Shipping:
Inventory:4,493
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Product details
Overview
LE79R70-1DJC from Zarlink Semiconductor is a bipolar monolithic Ringing Subscriber Line Interface Circuit (RSLIC) designed for short-loop telephony CPE applications. It integrates on-chip trapezoidal-wave ringing, dual battery switching (VBAT1: –40 V to –67 V; VBAT2: –19 V to VBAT1), programmable constant-current feed (IL = 18–39 mA), and two on-chip relay drivers. It serves as the line interface in ISDN Terminal Adaptors and set-top boxes.
For engineers reviewing the LE79R70-1DJC datasheet, LE79R70-1DJC pinout, LE79R70-1DJC application, or LE79R70-1DJC equivalent, key selection criteria include its on-chip ring-trip detection, polarity reversal support (–1 grade only), ground-key/tip-open supervision, and PLCC-32 polarized reverse package compatibility with legacy telephony line cards.
Technical Context
The LE79R70-1DJC implements full BORSHT functionality-battery feed, overvoltage protection, ringing, supervision, hybrid, and test-with integrated analog power amplifiers (A/TIP and B/RING), a current gain of 1000 at RSN, and programmable loop-detect thresholds via RD resistor. Its dual-battery architecture dynamically selects VBAT1 (high-voltage standby) or VBAT2 (low-voltage active) using TTL-compatible B2EN control.
Supervision logic uses C3–C1 decoding to select detector modes (ring-trip, off-hook, ground-key, tip-open), while DET provides open-collector output with internal 15 kΩ pull-up. The device supports on-hook transmission (OHT) and programmable open-circuit voltage via RSGH/RSGL resistors, all operating within 0°C to +70°C ambient range.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Supply Voltage (VBAT1) | –40 V to –67 V: Enables compliance with global POTS open-circuit voltage requirements (e.g., –48 V nominal, –67 V max). |
| Loop Current (IL) | 18–39 mA: Programmable constant-current feed across active/standby states; supports 600 Ω loop load per Bellcore GR-357. |
| Ringing Output (VAB) | 57–61 Vpk at –67 V VBAT1, 1570 Ω load: Delivers trapezoidal ringing meeting ITU-T G.961 and ANSI T1.401 standards. |
| Current Gain | 1000× at RSN pin: Enables precise metallic current sensing and impedance programming for 2-wire termination (ZSL = 600 Ω typical). |
| Operating Temperature | 0°C to +70°C ambient: Qualified for commercial-grade telephony equipment including IADs, DSL modems, and residential gateways. |
| Package | 32-pin PLCC, Polarized Reverse: Pin-compatible with industry-standard SLIC footprints; green RoHS-compliant assembly. |
| Power Dissipation | Max 1.67 W at TA = 70°C: Thermal design accommodates high-voltage analog operation without external heatsinking. |
Pinout & Package
LE79R70-1DJC is housed in a 32-pin PLCC (Plastic Leaded Chip Carrier), Polarized Reverse variant - distinguished by reversed corner marking and pin 1 orientation per JEDEC MO-118. This green RoHS-compliant package requires no external –5 V supply due to integrated VEE regulator.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| A(TIP) | Output amplifier anode | Drives TIP line with ±150 mA peak current; connects to high-pass filter capacitor HPA. |
| B(RING) | Output amplifier cathode | Drives RING line; forms metallic pair with A(TIP); connects to HPB capacitor. |
| VBAT1 / VBAT2 | Dual battery inputs | VBAT1 supplies high-voltage standby (–40 V to –67 V); VBAT2 supplies low-voltage active (–19 V to VBAT1); selected via B2EN. |
| RDC | DC feed programming node | Connects to RDC1/RDC2 network to set loop current; also ties to receiver summing node (RSN) for gain/impedance synthesis. |
| RYOUT1 / RYOUT2 | Open-collector relay drivers | Each sinks up to 75 mA; share common emitter RYE; used for line switching, polarity reversal, or hook-switch control. |
| DET | Programmable detector output | Open-collector logic-low output indicating tripped condition (ring-trip, off-hook, ground-key); internal 15 kΩ pull-up to VCC. |
Key Features
| Feature | Design Value |
|---|---|
| On-chip trapezoidal ringing | Eliminates external ringing transformers and discrete timing components; reduces BOM count and PCB area in ISDN-TA and set-top box designs. |
| Dual-battery switching | Reduces standby power by >50% vs. single-battery SLICs: VBAT2 (–24 V) used during off-hook; VBAT1 (–67 V) engaged only for on-hook OCV compliance. |
| Programmable loop-detect threshold | RD resistor sets resistance-based transition point between on-hook/off-hook states; supports configurable line-length adaptation (e.g., 2–10 kft loops). |
| Ground-key and tip-open detection | Enables ground-start signaling required by legacy PBX and enterprise systems; E1 pin selects between ground-key (E1=0) and off-hook (E1=1) modes. |
| Integrated VEE regulator | Removes need for external –5 V rail: VNEG pin self-generates regulated negative supply from VBATx, simplifying power architecture. |
Applications
| ISDN Terminal Adaptor (TA) | DSL Modem Line Card |
|---|---|
Use Scenario: Provides POTS line interface in ISDN-TA units connecting analog phones/faxes to digital ISDN networks. IC Role / Device Role / Timing Role: Full BORSHT SLIC performing battery feed, ringing generation, loop supervision, and hybrid 2-wire/4-wire conversion. Use Value: On-chip ringing eliminates transformer cost and size; dual-battery mode cuts standby power to <100 mW, enabling fanless enclosure design. | Use Scenario: Implements voice line interface in residential DSL modems supporting VoIP and PSTN fallback. IC Role / Device Role / Timing Role: Line driver and supervisor handling off-hook detection, polarity reversal, and on-hook transmission (OHT) for call progress tones. Use Value: Programmable RDC network enables precise 20 mA loop current matching DSLAM requirements; RSN-based impedance synthesis ensures stable echo cancellation. |
| Smart Residential Gateway | FXS Voice Card |
Use Scenario: Integrates analog telephony service into multi-function home gateways with Wi-Fi, routing, and VoIP. IC Role / Device Role / Timing Role: Ringing SLIC managing ringing delivery, ring-trip detection, and battery switching for multiple FXS ports. Use Value: Ring-trip detector (RTRIP1/RTRIP2) enables fast disconnect recognition (<10 ms); trapezoidal waveform meets FCC Part 68 ring cadence specs. | Use Scenario: Serves as line interface on plug-in FXS cards for IP-PBX and VoIP media gateways. IC Role / Device Role / Timing Role: Supervisory SLIC providing polarity reversal, ground-key detection, and relay-controlled line switching (via RYOUT1/RYOUT2). Use Value: Two integrated relay drivers eliminate external driver ICs; tip-open state supports ground-start lines per ANSI T1.401 Annex A. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar ringing SLIC applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| Zarlink LE79R70DJC | No polarity reversal support; non-polarized PLCC package; same electrical specs and pinout except B2EN behavior. | Suitable for non-reversal applications like basic IADs; lacks E1-controlled ground-key mode. | Select LE79R70DJC when polarity reversal and ground-start signaling are not required. |
| Zarlink LE79R100-1DJC | Higher ringing voltage capability (up to –80 V VBAT1); enhanced thermal performance (θJA = 25°C/W in QFN); identical PLCC-32 pinout. | Preferred for long-loop or high-temperature deployments (e.g., outdoor NIUs); supports wider VBAT1 range. | Choose LE79R100-1DJC for extended loop reach (>15 kft) or elevated ambient temperature environments. |
Compared with LE79R70-1DJC, LE79R70DJC omits polarity reversal and ground-key detection but retains identical ringing and feed performance; LE79R100-1DJC extends VBAT1 range and improves thermal dissipation, making it suitable for higher-power or longer-loop deployments where LE79R70-1DJC may require derating.
Availability
LE79R70-1DJC is available at Aetrix Electronics and suitable for Integrated Access Devices (IADs), DSL modems, and smart residential gateways requiring stable component supply across multi-year production cycles.
Supply support for LE79R70-1DJC 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-voltage analog telephony solutions for global carrier and CPE markets.
The LE79R70-1DJC belongs to Zarlink's VE580 Series RSLIC product line, engineered specifically for cost-sensitive, short-loop customer premises equipment where integration of ringing, battery switching, and supervision reduces system-level BOM and layout complexity.
FAQ
What is the primary function of the LE79R70-1DJC in telephony systems?
The LE79R70-1DJC serves as a Ringing Subscriber Line Interface Circuit (RSLIC), delivering full BORSHT functionality-including battery feed, ringing generation, loop supervision, and hybrid conversion-for analog telephone line interfaces. It replaces discrete SLIC+ringing generator combinations in devices like ISDN Terminal Adaptors and DSL modems, with LE79R70-1DJC integrating trapezoidal ringing and dual-battery switching on a single die.
Does the LE79R70-1DJC support polarity reversal, and how is it enabled?
Yes, the LE79R70-1DJC supports polarity reversal-but only in the "–1" performance grade, as confirmed in the datasheet's Table 1 footnote. Polarity reversal is activated via C3–C1 input coding (codes 6 and 7) and requires proper configuration of external relay drivers RYOUT1/RYOUT2. The LE79R70-1DJC must be used with compatible control logic to assert the correct decoder pattern and drive relays for line reversal; LE79R70-1DJC itself does not contain internal polarity switches.
How does the dual-battery architecture of the LE79R70-1DJC reduce power consumption?
The LE79R70-1DJC reduces standby power by switching between VBAT2 (–19 V to –24 V) during off-hook/active states and VBAT1 (–40 V to –67 V) only during on-hook standby to meet open-circuit voltage requirements. This cuts quiescent power to <100 mW in open-circuit state-verified in Electrical Characteristics table-compared to single-battery SLICs drawing >200 mW continuously. The B2EN pin controls selection, and LE79R70-1DJC's internal logic ensures seamless transition without disrupting supervision.
What are the critical external components required for LE79R70-1DJC ringing waveform shaping?
The LE79R70-1DJC requires three key external components for trapezoidal ringing: RINGIN (CMOS-compatible square wave input), plus an RC network comprising RSLEW (150 kΩ) and CSLEW (0.33 µF) to set rise time (~10 ms at 20 Hz), and RDCR (2 kΩ) for feedback during ringing. These values are specified in the datasheet's Ring-Trip Components section and Application Circuit. Deviation affects crest factor and ring-trip reliability; LE79R70-1DJC does not generate ringing autonomously-it conditions and amplifies the input waveform.
Can the LE79R70-1DJC be used in non-telephony applications such as industrial analog signal conditioning?
No-the LE79R70-1DJC is purpose-built for telephony line interface duties and is not characterized or qualified for general-purpose analog signal conditioning. Its high-voltage outputs (±150 mA, –67 V capable), BORSHT-specific supervision logic, and ringing timing dependencies make it unsuitable outside POTS/ISDN/DSL CPE contexts. Parameters like THD (–50 dB), return loss (26 dB), and longitudinal balance (40 dB) are optimized for voiceband telecom standards-not wideband or DC-coupled instrumentation. Use LE79R70-1DJC only in validated telephony applications.
LE79R70-1DJCT Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Microchip Technology
- Series:
- -
- Package/Case:
- 32-LCC (J-Lead)
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Obsolete
- Function:
- Subscriber Line Interface Concept (SLIC)
- Interface:
- 2-Wire
- Number of Circuits:
- 1
- Voltage - Supply:
- 4.75V ~ 5.25V
- Current - Supply:
- -
- Power (Watts):
- -
- Operating Temperature:
- 0°C ~ 70°C
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 32-PLCC (11.43x13.97)
LE79R70-1DJCT FAQ
1.How can I place an order for LE79R70-1DJCT through Aetrix?
Please submit a Request for Quotation (RFQ) for LE79R70-1DJCT on Aetrix. Our sales agent will provide a competitive quotation and guide you through the order confirmation once you accept the terms.
2.Are the price and stock information for LE79R70-1DJCT reliable?
The price and inventory of LE79R70-1DJCT are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LE79R70-1DJCT is usually 5 days.
3.What payment methods are accepted for LE79R70-1DJCT?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LE79R70-1DJCT transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LE79R70-1DJCT?
LE79R70-1DJCT orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LE79R70-1DJCT order is processed, you will receive an email with the shipment details and tracking number.
Note: Tracking information may take up to 24 hours to appear. Express delivery typically takes 3–5 business days.
5.How can I obtain technical support or documentation for LE79R70-1DJCT?
For technical support, including LE79R70-1DJCT datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LE79R70-1DJCT requirements.
6.How does Aetrix verify that LE79R70-1DJCT is sourced from the original manufacturer or authorized distributors?
All LE79R70-1DJCT products on Aetrix are procured from qualified distributors and authorized channels. Our dedicated quality assurance team conducts strict verification, including traceability checks and, if necessary, third-party testing. This ensures that LE79R70-1DJCT meets industry standards.
7.What is the process for return or replacement of LE79R70-1DJCT?
All LE79R70-1DJCT units undergo pre-shipment inspection (PSI). If there is an issue with LE79R70-1DJCT, returns or replacements are accepted under the following conditions:
1.Quantity discrepancies, incorrect items, or visible external defects (such as breakage or corrosion), acknowledged by Aetrix.
2.The issue is reported within 90 days of delivery.
3.The LE79R70-1DJCT part is unused and in its original packaging.
Return procedure for LE79R70-1DJCT:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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