CS223-4M - 4A 600V Surface Mount SCR | Central Semiconductor
MPN: CS223-4M β Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $0 | $0.00 |
| 10 | $0 | $0.00 |
| 100 | $0 | $0.00 |
| 500 | $0 | $0.00 |
| 1,000 | $0 | $0.00 |
CS223-4M Overview
An SCR, or silicon controlled rectifier, is a three-terminal thyristor that acts as a latching switch: once a small gate trigger current is applied between gate and cathode, the device conducts from anode to cathode and remains on until the anode current falls below the holding current. In the power-electronics hierarchy, the SCR sits among thyristors alongside TRIACs and DIACs, and is the workhorse of half-wave and full-wave controlled rectification, crowbar overvoltage protection, and phase-control circuits.
Key features of the CS223-4M include a 4.0 A average on-state current rating, 600 V repetitive peak off-state voltage, a compact surface mount SOT-223 case with a thermally conductive tab, and epoxy molded construction designed for sensing circuit applications and control systems. The SOT-223 tab (which is electrically common to the anode) provides a low-resistance thermal path to the PCB copper, allowing several watts of dissipation without an external heatsink.
The device uses standard-recovery silicon thyristor technology optimized for line-frequency (50/60 Hz) applications rather than high-frequency switching. Its latching behavior makes it well suited to crowbar circuits that dump fault energy into a shunt path, overvoltage sensing, and gating of loads driven from rectified AC mains.
Typical applications include AC power control, overvoltage crowbar protection in linear power supplies, sensing and alarm latch circuits, and industrial control systems where a robust, low-cost latching switch is required.
When designing with this SCR, ensure the gate trigger current is available under worst-case cold-temperature conditions, and verify that latching current is reached before the trigger pulse ends; a snubber across anode-cathode suppresses dv/dt false triggering. This page synthesizes distributor data, drop-in family alternatives, and practical design notes not found in the manufacturer datasheet.
Drop-in alternatives for CS223-4M β same package, pin-to-pin compatible. Different-package parts requiring PCB rework are excluded.
Quick Comparison Tool β Select alternative parts for side-by-side comparison:
CS223-4N
β Drop-Inπ Reference alternative (not in catalog)
CS223-2M
β Drop-Inπ Reference alternative (not in catalog)
CS223-4M Specifications
| Device Type | Silicon Controlled Rectifier (SCR) |
| Repetitive Peak Off-State Voltage (VDRM/VRRM) | 600 V |
| Average On-State Current (IT(AV)) | 4 A |
| Configuration | Single SCR |
| Recovery Type | Standard Recovery |
| Mounting Type | Surface Mount |
| Package | SOT-223 |
| Construction | Epoxy Molded |
| Primary Applications | Sensing circuits and control systems |
| Family Voltage Grades | 600 V (CS223-4M) / 800 V (CS223-4N) |
| Marking | Full part number |
CS223-4M Pin Configuration
| Pin 1 | Gate (G) β Gate trigger terminal - positive current into gate fires the SCR (per datasheet case outline) |
| Pin 2 | Anode (A) β Anode terminal (per datasheet case outline) |
| Pin 3 | Cathode (K) β Cathode terminal (per datasheet case outline) |
| Pin 4 | Anode (Tab) β Mounting tab, electrically common with the anode - primary thermal path (per datasheet case outline) |
Typical Applications
CS223-4M is suitable for 6 applications: Overvoltage Crowbar Protection, AC Line Phase Control, Sensing and Alarm Latch Circuits, Industrial Control Systems, Battery Charger and Rectifier Control, Test and Measurement Fixtures.
Overvoltage Crowbar Protection
The CS223-4M's latching SCR behavior and 600 V blocking rating make it a natural fit for crowbar circuits that protect low-voltage rails in linear and switching power supplies. A sensing reference (zener, TL431, or dedicated OVP IC) fires the gate when the rail exceeds its threshold; the SCR then latches hard and shunts fault current, forcing a fuse or upstream limit to act. Its 4.0 A average rating and SOT-223 tab soldered to a copper pour absorb the fault energy transient, and the 600 V off-state rating gives enormous margin on 5 V, 12 V, or 24 V rails. Unlike a resettable protection IC, the crowbar stays latched until power is removed, guaranteeing that a persistent fault cannot be missed.
Recommended
AC Line Phase Control
In half-wave and full-wave phase-control circuits, the CS223-4M conducts a controllable portion of each AC half-cycle after being gate-triggered by a delay circuit, enabling lamp dimming, heater power regulation, and small motor speed control. The 600 V repetitive peak rating comfortably covers 120 VAC and 230 VAC line waveforms with headroom, while the 4 A average current supports resistive loads up to several hundred watts with adequate heatsinking. Because the SCR turns off naturally at the current zero crossing each cycle, its standard-recovery characteristic is entirely adequate at 50/60 Hz, and gate drive can come from simple RC phase-shift networks or opto-triac drivers referenced to the cathode.
Recommended
Sensing and Alarm Latch Circuits
Central Semiconductor explicitly designed the CS223-4M for sensing circuit applications: a small sensor signal (thermistor bridge, pressure switch, photocell, or overcurrent shunt amplifier) injects a few milliamperes into the gate, and the SCR latches the alarm state indefinitely without needing the sensor signal to persist. The latched output can drive a buzzer, relay, or LED directly from the anode path, and the SOT-223 surface mount footprint suits compact alarm PCBs. Designers should include a gate-to-cathode resistor (typically 1 kohm) to desensitize the trigger against leakage and noise, and reset is performed simply by momentarily interrupting the supply, keeping the latch circuit minimal and low cost.
Recommended
Industrial Control Systems
Factory automation and industrial control panels frequently need a rugged, inexpensive latching element to command contractors, solenoids, or indicator stacks from rectified AC logic rails. The CS223-4M's epoxy molded SOT-223 construction, 4 A rating, and 600 V off-state capability withstand the line transients typical of industrial environments, and its standard-recovery thyristor die tolerates the inrush of solenoid and relay loads. A snubber network across the anode-cathode pair suppresses dv/dt false triggering from contactor coils, and the surface mount format supports modern mixed-technology control boards. Per the datasheet, control systems are one of the two primary intended application spaces for the CS223 family.
Recommended
Battery Charger and Rectifier Control
Controlled rectifier battery chargers use the CS223-4M to regulate charge current by varying the SCR firing angle on the rectified AC input; the 600 V rating covers the transformer secondary voltage of common 12 V and 24 V charger designs with wide margin. Because the device commutates naturally at each zero crossing, no forced turn-off circuitry is required, simplifying the charger topology to a gate-pulse generator plus the SCR. The 4 A average current class suits chargers up to roughly 100 W output with conservative copper heatsinking of the SOT-223 tab, and latching gate drive from a simple comparator ensures reliable startup into deeply discharged batteries where load current is highest at turn-on.
Recommended
Test and Measurement Fixtures
Bench and automated test equipment often needs a one-shot fault injector or a protective latching clamp that trips once on an overvoltage or overcurrent event and stays tripped for operator inspection. The CS223-4M fills this role economically: its 600 V rating survives fixture transients, the 4 A rating handles repeated crowbar events into a current-limited source, and the SOT-223 surface mount package integrates directly onto fixture PCBs. A microcontroller GPIO through a current-limiting resistor provides precise, repeatable gate triggering, and the latched state provides a clear, unambiguous fault flag that persists until the operator resets the fixture power.
Recommended
Recommended Products Summary
Engineering reference data for CS223-4M β comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | CS223-4N | CS223-2M |
|---|---|---|---|
| Package | SOT-223 | SOT-223 - same | SOT-223 - same |
| Brand | Central Semiconductor | Central Semiconductor | Central Semiconductor |
| Repetitive Peak Off-State Voltage (VDRM) | 600 V | 800 V | 600 V |
| Average On-State Current (IT(AV)) | 4 A | 4 A | 2 A |
| Recovery Type | Standard Recovery | Standard Recovery | Standard Recovery |
| Mounting Type | Surface Mount | Surface Mount | Surface Mount |
| Intended Applications | Sensing circuits and control systems | Sensing circuits and control systems (higher voltage) | Sensing circuits and control systems (lower current) |
| Drop-in Compatibility | Reference footprint | Pin-to-pin, same footprint, fully interchangeable | Pin-to-pin, same footprint, current rating reduced 50% |
Key Differentiators
- Full 4 A current class in a compact surface mount case (vs CS223-2M)
- 600 V blocking with a higher-voltage family sibling available (vs CS223-4N)
- Purpose-built for sensing and control latch duties (vs Generic power SCRs)
Design Notes
In SOT-223 SCRs the tab is the anode and the main thermal path; connect it to a copper pour of at least 25 mm x 25 mm (about 1 square inch) on the top layer, plus stitched vias to a ground or anode plane, to keep junction temperature rise acceptable at multi-amp surge events. Estimated: if the SCR dissipates ~4 W peak (4 A x ~1 V on-state), a theta JA around 60-90 C/W with minimal copper would push junction temperature above safe limits, so generous copper is not optional. Keep gate traces short and away from anode-switching nodes to avoid capacitive false triggering.
SCRs latch - this is the most common design mistake. Ensure that once triggered, the load current exceeds the datasheet latching current (IL) before the gate pulse ends, otherwise the CS223-4M will not stay on. Conversely, confirm the circuit can always reduce anode current below the holding current (IH) when turn-off is required; on DC rails an SCR cannot turn off by gate control at all. Also respect the datasheet dv/dt rating: fast-rising anode voltage (from contactor switching or line transients) can self-trigger the device, so add an RC snubber (e.g., 100 ohm + 0.1 uF as a starting point) where needed.
Use a gate series resistor sized to deliver the datasheet gate trigger current (IGT) from the available drive voltage, and add a gate-to-cathode resistor (1 kohm typical) to shunt leakage and improve dv/dt immunity at high temperature. For crowbar duty, verify that the fault energy (I^2 t of the fuse clearing event) stays within the datasheet surge rating (ITSM); choose the upstream fuse so it clears before the SCR's single-cycle surge limit is exceeded. Estimated: a 10 A, 10 ms fault deposits roughly 1 A^2s, which must be compared directly against the datasheet ITSM curve before release.
Compliance Information
DigiKey lists a 'PBFREE' ordering code (CS223-4M TR PBFREE), suggesting a lead-free/Pb-free variant is offered; full RoHS/REACH status should be confirmed on the official Central Semiconductor product page.
