CMPP6027R - 40V 150mA Programmable UJT SOT-23 | Central Semiconductor
MPN: CMPP6027R β Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $0.52 | $0.52 |
| 10 | $0.41 | $4.10 |
| 100 | $0.29 | $29.00 |
| 500 | $0.22 | $110.00 |
| 1,000 | $0.17 | $170.00 |
CMPP6027R Overview
A programmable unijunction transistor (PUT) is a four-layer PNPN threshold switching device whose anode-gate-cathode terminals resemble a small thyristor. Unlike a fixed-ratio UJT, a PUT fires when the anode voltage exceeds the gate voltage plus one PN junction drop, and because the gate is externally accessible, designers set the trigger threshold, peak current, valley current, and standoff ratio with two resistors. PUTs therefore occupy the same functional niche as neon lamps and Schmitt triggers in low-frequency relaxation oscillators, timing circuits, and voltage-detection latches within the broader thyristor and semiconductor family.
Key differentiating features of the CMPP6027R include its 40V anode-cathode rating for headroom on industrial rails, 150mA pulse output capability sufficient to drive optocoupler LEDs or thyristor gates directly, fully adjustable IP and IV characteristics, and the compact SOT-23 surface mount footprint that lets designers retrofit through-hole PUT designs such as the 2N6027 into modern PCBs. The device complements Central Semiconductor's CMPP6028R, which offers a different intrinsic standoff ratio binning within the same package.
Architecturally, the CMPP6027R is an anode-gate thyristor: forward biasing the anode-gate junction injects gate current, regeneratively turns on the PNPN structure, and latches the anode-cathode path into conduction until the anode current falls below the programmable valley current. This negative-resistance switching behavior is the basis of its use in relaxation oscillators and level-sensitive triggers.
Typical applications include sawtooth and pulse relaxation oscillators, time-delay timers, thyristor and triac gate triggering, overvoltage crowbar sensing, and voltage-monitoring alarm circuits where a precise, adjustable threshold is required at minimal BOM cost.
Design consideration: because IP, IV, and eta are set by the external R1-R2 gate divider, resistor tolerance directly shifts the trip point; use 1% resistors and confirm the divider current comfortably exceeds the datasheet peak current at the lowest operating temperature.
This page adds value beyond the datasheet by consolidating distributor availability, drop-in alternative analysis, application guidance, and pricing context for the CMPP6027R in one reference.
Drop-in alternatives for CMPP6027R β same package, pin-to-pin compatible. Different-package parts requiring PCB rework are excluded.
Variants in this series
Same-series models that are drop-in compatible with CMPP6027R (same form factor and footprint) β differing in Device Type, Package.
Quick Comparison Tool β Select alternative parts for side-by-side comparison:
CMPP6028R
β Drop-Inβ In Stock
Contact for price
View Datasheet βCMPP6028R BK
β Drop-Inπ Reference alternative (not in catalog)
CMPP6027R BK
β Drop-Inπ Reference alternative (not in catalog)
CMPP6027R Specifications
| Device Type | Programmable Unijunction Transistor (PUT) |
| Anode-Cathode Voltage (max) | 40 V |
| Peak Output Current (max) | 150 mA |
| Power Dissipation | 167 mW |
| Package | SOT-23 (TO-236-3, SC-59, SOT-23-3) |
| Mounting Type | Surface Mount |
| Programmable Parameters | Valley current (IV), peak current (IP), intrinsic standoff ratio (eta) |
| Terminal Count | 3 |
| Configuration | Anode-Gate Thyristor (PNPN) |
| Packaging Option | Tape and Reel (CMPP6027R TR) |
CMPP6027R Pin Configuration
| Pin 1 | Anode (A) β Anode terminal; trigger voltage applied here |
| Pin 2 | Cathode (K) β Cathode terminal; return path for switched current |
| Pin 3 | Gate (G) β Programmable gate; connect to external resistor divider to set IP, IV, and eta |
Safe Operating Area
Typical Applications
CMPP6027R is suitable for 6 applications: Relaxation Oscillators, Thyristor and TRIAC Gate Triggering, Time-Delay Timers, Overvoltage Crowbar Sensing, Voltage-Level Detectors and Alarm Latches, Sawtooth and Ramp Generators.
Relaxation Oscillators
The CMPP6027R is a natural fit for RC relaxation oscillators because its peak current, valley current, and intrinsic standoff ratio are all programmable through a two-resistor gate divider, letting one device cover a wide frequency range. A capacitor charges through a timing resistor until the anode reaches the gate threshold plus one PN drop; the PUT then fires and dumps the capacitor through the anode-cathode path, producing a sharp pulse or sawtooth. Because firing occurs when the divider supplies the datasheet IP, the timing resistor must stay below the extinction limit defined by eta and the supply voltage. The 40V rating supports oscillator rails well above logic levels, and the SOT-23 footprint keeps the oscillator compact.
Recommended
Thyristor and TRIAC Gate Triggering
In phase-control and crowbar circuits, the CMPP6027R generates the sharp, high-current gate pulse needed to fire SCRs and triacs reliably. Its 150mA peak output current exceeds the gate-trigger requirement of most sensitive-gate and standard SCRs, while the programmable threshold allows the firing point to track a ramp or phase-delay network precisely. The negative-resistance switching of the PUT yields pulse rise times far faster than a comparator-plus-driver chain at comparable BOM cost, and the 40V anode-cathode rating tolerates rectified industrial rails. Designers should confirm the pulse energy stays within the 167 mW package dissipation envelope by limiting duty cycle at high repetition rates.
Recommended
Time-Delay Timers
Long-interval timers benefit from the CMPP6027R's programmable threshold: an RC network charges toward the gate-set trip point, and the PUT fires only when the anode crosses the programmed voltage, after latching current requirements (IP) are met. Because eta is set by resistors rather than fixed by silicon, the same circuit can deliver seconds-to-minutes delays by scaling R and C, and the low quiescent draw of an untriggered PUT keeps standby drain minimal in battery-backed equipment. The 150mA output can directly drive a relay driver, optocoupler LED, or small thyristor at time-out. Use low-leakage timing capacitors to preserve long-delay accuracy over temperature.
Recommended
Overvoltage Crowbar Sensing
As a crowbar sense element, the CMPP6027R monitors a supply rail through its gate divider and fires a thyristor latch when the rail exceeds the programmed threshold, crowding the fault into a short and blowing a fuse. The programmable standoff ratio lets designers set the trip point to millivolt-level precision relative to the rail, and the PUT's regenerative PNPN switching gives an abrupt, well-defined transition without comparator propagation-delay ambiguity. The 40V rating covers 24V-class industrial rails with margin. Place the PUT close to the SCR gate to minimize trigger-path inductance, and verify the sense divider current keeps the anode above IP at the trip point across temperature.
Recommended
Voltage-Level Detectors and Alarm Latches
Battery and line monitors use the CMPP6027R as a latch-style level detector: once the sensed voltage crosses the resistor-programmed gate threshold, the PUT fires and remains latched until reset, providing a non-volatile event flag. The programmable IP and IV characteristics allow the designer to trade sensing threshold against standby current - a key requirement in battery-powered alarm and telemetry equipment. The 150mA latched output can drive an LED, buzzer, or optocoupler directly without an additional transistor stage. The SOT-23 surface mount package supports compact PCB layouts in portable devices, and the 40V rating permits monitoring of high-voltage stacks through an appropriate divider.
Recommended
Sawtooth and Ramp Generators
The CMPP6027R produces linear ramp and sawtooth waveforms for CRT-style deflection simulation, ADC stimulus, and PWM ramp references. A constant-current source charges the timing capacitor until the anode reaches the programmed gate threshold; the PUT rapidly discharges the capacitor through a small resistor, resetting the ramp. Because eta and IP are programmable, ramp amplitude and reset point can be tuned by resistor selection rather than device selection, easing procurement. The fast anode-cathode switching transition yields short reset times, preserving ramp linearity at higher frequencies, while the 40V rating supports large-amplitude ramps. Keep discharge current pulses within the 167 mW average dissipation limit.
Recommended
Engineering reference data for CMPP6027R β comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | CMPP6028R | CMPP6028R BK | CMPP6027R BK |
|---|---|---|---|---|
| Package | SOT-23 (TO-236-3) | SOT-23 (TO-236-3) - same | SOT-23 (TO-236-3) - same | SOT-23 (TO-236-3) - same |
| Brand | Central Semiconductor | Central Semiconductor | Central Semiconductor | Central Semiconductor |
| Anode-Cathode Voltage | 40 V | 40 V | 40 V | 40 V |
| Peak Output Current | 150 mA | 150 mA | 150 mA | 150 mA |
| Power Dissipation | 167 mW | 167 mW | 167 mW | 167 mW |
| Intrinsic Standoff Ratio Binning | CMPP6027 grade | CMPP6028 grade (different bin) | CMPP6028 grade (different bin) | CMPP6027 grade - same |
| Programmable Parameters | IP, IV, eta | IP, IV, eta | IP, IV, eta | IP, IV, eta |
| Packaging Option | Tape & Reel (TR) | Tape & Reel (TR) | Bulk (BK) | Bulk (BK) |
Key Differentiators
- Fully programmable switching characteristics (vs CMPP6028R)
- Surface mount retrofit of classic PUT functions (vs 2N6027 (TO-92))
- High-voltage headroom in a tiny package (vs CMPP6028R BK)
Design Notes
The CMPP6027R only fires if the gate divider can supply the datasheet peak current (IP) at the trigger point. If the divider resistors are too large, the anode voltage will rise past the intended threshold without firing, or firing will be erratic at temperature extremes. Per the Central Semiconductor CMPP6027R series datasheet, size R1 and R2 so that divider current through the anode-gate path exceeds IP by a comfortable margin across the full temperature range, while keeping quiescent drain within your power budget.
Estimated: the 167 mW SOT-23 dissipation limit applies to time-averaged power. For a PUT firing 150 mA pulses with roughly 1 V on-state drop, 10 us pulses at 1 kHz average about 1.5 mW - negligible. But continuous latch operation near 40V rails must be avoided; the anode current must fall below the programmed valley current (IV) to reset. Always verify duty-cycle-weighted dissipation, not peak numbers, against the 167 mW envelope and derate at elevated ambient per the datasheet curve.
Place the gate divider resistors close to the SOT-23 gate pin and keep the timing capacitor's discharge loop (capacitor to anode, cathode to ground) short to minimize ringing on the output pulse. For thyristor-gate-driving applications, route the gate pulse trace directly and add a small gate-kathode resistor on the SCR to improve dv/dt immunity. The SOT-23 land pattern should follow the standard TO-236-3 footprint with adequate copper on the cathode tab for heat spreading.
Compliance Information
Compliance status not stated in the provided verified web data; consult Central Semiconductor product page (my.centralsemi.com) for current RoHS/REACH declarations.
