Rochester Electronics, LLC CA3079

The CA3079 synchronizes thyristor firing with the AC line crossing to reduce switching interference in suitable resistive-load designs. The manufacturer-authored CA3059/CA3079 documentation describes operation with appropriately designed external circuitry for 24 V, 120 V, 208/230 V or 277 V AC at 50/60 Hz or 400 Hz. These are application line-voltage options, not direct IC supply ratings.

• Zero-cross synchronized switching for a thyristor or triac.
• Integrated limiter supply can derive operating power from the AC line.
• Differential on/off sensing supports external command or sensor circuits.
• Four functional blocks reduce discrete control circuitry.
• Through-hole 14-lead package supports maintenance of legacy boards.

The documented blocks are a limiter-power supply, differential on/off sensing amplifier, zero-crossing detector and triac-gating circuit. A line-input series resistor and external components must be selected for the actual mains voltage and dissipation. CA3079 omits the CA3059-only fail-safe sensor protection, external trigger, inhibit and DC-mode functions; the two devices must not be treated as drop-in functional equivalents.

The original manufacturer document specifies a 14-lead plastic dual-inline package. The exact Rochester catalog listing describes a 14-PDIP, 0.300 inch (7.62 mm) row-spacing package. The package register includes 14-DIP but marks its artwork missing; its exact drawing must be verified before new layout work.

Assembly checks

• Confirm notch orientation and lead-one position.
• Compare body, lead and row dimensions with the controlled drawing.
• Verify actual markings and tube or bulk supply form.

The registered 14-DIP JPG is absent locally.

The CA3079 top-view pinout assigns pin 2 to DC supply, pin 3 to high-current negative trigger, pin 4 to trigger output, pin 5 to AC input, pins 7 and 8 to common, pin 9 to sense-amplifier reference, pin 10 to resistor-driver positive supply, pin 11 to resistor-driver common and pin 13 to sense-amplifier input. Pins 1, 6, 12 and 14 are explicitly marked do not use for CA3079. Consult the controlled pinout before wiring the mains interface.

Absolute maximum values are stress limits, not recommended operating conditions. Recheck the exact revision, test circuit and external resistor sizing before design release.

No database-verified drop-in replacement is linked. Although CA3059 shares the basic zero-cross switching architecture and package family, it adds auxiliary functions and has different terminal-use requirements and ratings. Any substitution requires a schematic, pin-use, resistor, thermal and safety review.

Rochester Electronics' manufacturer-branded REI datasheet identifies CA3059 and CA3079 and states that its accompanying original-manufacturer data reflects Rochester-manufactured devices. The original Harris/Intersil document gives the CA3079-specific feature comparison and pinout. The catalog identifies Rochester Electronics, LLC as this item's supplier.

• Legacy heater and lamp controls.
• AC relay or valve actuation circuits.
• Motor on/off control where the documented circuit is suitable.
• Industrial sensor or command-signal switching interfaces.

Confirm manufacturer traceability, exact device markings, lead condition and age-related storage history. A DigiKey Marketplace listing for the exact Rochester code was indexed with 7,716 units and USD 30.15 at quantity 10; that snapshot is not a live checkout quote. It conflicts with this catalog's 7,778 units, USD 12.50 and minimum quantity 12, so stock, seller terms and price tiers must be reconciled before publication or a customer quote.

AC line voltage is hazardous. Validate isolation, creepage, fusing, resistor wattage, surge behavior, thermal limits and applicable safety approvals at the board level. Do not use CA3059-only pins or functions on CA3079. The missing package JPG and unreconciled live stock/pricing prohibit publication.