UCC28C42DR - 20V 1A Current-Mode PWM Controller | TI
MPN: UCC28C42DR ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $0.62 | $0.62 |
| 10 | $0.55 | $5.50 |
| 100 | $0.44 | $44.00 |
| 500 | $0.36 | $180.00 |
| 1,000 | $0.29 | $290.00 |
UCC28C42DR Overview
A current-mode PWM controller is an integrated circuit that regulates switching power supply output voltage by controlling the duty cycle of a power switch based on both the voltage error signal and the inductor current. Compared with voltage-mode controllers, the dual-loop current-mode architecture provides better line and load regulation, inherent cycle-by-cycle overcurrent protection, and simpler loop compensation. Current-mode controllers are the standard choice in AC-DC adapters, flyback converters, and isolated power supplies.
Key features include a 20V supply voltage rating, 1A peak gate-drive output current, and a maximum switching frequency of 1000 kHz. The UCC28C42 version provides a 14.5V startup (on) and 9V minimum operating (off) UVLO threshold with 100% duty cycle capability. BiCMOS technology reduces startup and operating current, improving efficiency over bipolar predecessors while supporting faster current-sense and oscillator operation.
Internally, the device integrates a precision oscillator (programmable via RT/CT components), an error amplifier, a current-sense comparator, a 5V reference (2% accuracy), and a totem-pole output driver. Cycle-by-cycle current limiting protects the external MOSFET during faults.
Typical applications include flyback converters, boost converters, and forward converters in industrial power supplies, telecom auxiliary rails, and AC-DC adapters. Its low quiescent current suits off-line auxiliary supplies where standby efficiency matters.
Design tip: keep current-sense and gate-drive traces short to minimize parasitic inductance, place RT/CT timing components close to pin 4, and add at least 0.1uF of bypass capacitance at VCC. Pricing as of 2026-08-29.
Drop-in alternatives for UCC28C42DR — 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 UCC28C42DR (same form factor and footprint) — differing in Maximum Switching Frequency, Pin Compatibility.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
UCC28C42QDRQ1
✅ Drop-In✓ In Stock
$1.4 / Unit
View Datasheet →UCC28C43DR
✅ Drop-In📋 Reference alternative (not in catalog)
UCC28C44DR
✅ Drop-In📋 Reference alternative (not in catalog)
UCC28C45DR
✅ Drop-In📋 Reference alternative (not in catalog)
UCC38C42DR
✅ Drop-In📋 Reference alternative (not in catalog)
UC3842ADR
✅ Drop-In📋 Reference alternative (not in catalog)
NCP1200D60R2G
⚡ Same Package ⚠️ Specs Unverified📋 Reference alternative (not in catalog)
UCC28C42DR Maximum Ratings & Electrical Characteristics
| Control Topology | Current-Mode PWM |
| Supply Voltage (Max) | 20 V |
| UVLO On Threshold | 14.5 V |
| UVLO Off Threshold | 9 V |
| Peak Output Drive Current | 1 A |
| Maximum Switching Frequency | 1000 kHz |
| Maximum Duty Cycle | 100% |
| Reference Voltage | 5 V (2% accuracy) |
| Technology | BiCMOS |
| Topologies Supported | Boost, Flyback, Forward |
| Package | 8-SOIC (D) |
| Mounting Type | Surface Mount |
| Operating Temperature | -40C to +85C (industrial) |
| Pin Compatibility | UCx84xA / UCx84x families |
| RoHS Status | Compliant |
| Packaging | Tape & Reel (R suffix) |
UCC28C42DR Pin Configuration
| Pin 1 | COMP — Error amplifier output, loop compensation node |
| Pin 2 | VFB — Inverting input of error amplifier, feedback voltage |
| Pin 3 | CS — Current sense input for cycle-by-cycle current limiting |
| Pin 4 | RT/CT — Oscillator timing resistor and capacitor connection |
| Pin 5 | GND — Ground reference |
| Pin 6 | OUT — Totem-pole gate drive output, 1A peak |
| Pin 7 | VCC — Supply voltage, 20V max, UVLO 14.5V/9V |
| Pin 8 | VREF — 5V precision reference output (2% accuracy) |
Typical Applications
UCC28C42DR is suitable for 6 applications: Off-line Flyback AC-DC Adapter, Industrial Power Supplies, Telecom Auxiliary Rails, Boost Converters, Standby and Auxiliary Supplies, Forward Converters.
Off-line Flyback AC-DC Adapter
The UCC28C42DR is a standard choice for off-line flyback adapters because its 14.5V/9V UVLO works with a bootstrap startup resistor and transformer aux winding: VCC charges through the resistor until 14.5V triggers startup, and the aux winding sustains operation above 9V. The 1000 kHz capability allows compact transformer designs, while cycle-by-cycle current limiting through the CS pin protects the primary MOSFET during overload or short circuit. BiCMOS low startup current reduces no-load losses, helping adapters meet standby power targets without extra circuitry.
Recommended
Industrial Power Supplies
In industrial switch-mode supplies, the UCC28C42DR's -40C to +85C industrial temperature range and 20V maximum supply rating suit harsh environments. It is used in boost and forward converter rails feeding PLCs, motor drives, and instrumentation. The 5V reference with 2% accuracy provides a stable error-amp reference for tight output regulation, while the current-mode architecture gives good line rejection against noisy industrial buses. Its pin compatibility with UC384x legacy parts makes it a low-risk efficiency upgrade for existing industrial boards without PCB changes.
Recommended
Telecom Auxiliary Rails
Telecom systems use the UCC28C42DR to generate auxiliary 12V or 5V rails from higher buses via flyback or boost stages. The 14.5V/9V UVLO ensures the controller does not start until the bus is valid, and the 100% duty-cycle capability supports boost topologies operating at high step-up ratios. Low operating current keeps auxiliary supply efficiency high, which matters when the aux rail runs continuously even when the main output is disabled. The 8-SOIC package fits density-constrained line cards and small base-station power modules.
Recommended
Boost Converters
With 100% maximum duty cycle and 1000 kHz operation, the UCC28C42DR fits boost converters raising low input voltages such as 12V industrial rails to higher outputs. Current-mode control simplifies compensation to a single dominant pole and provides inherent cycle-by-cycle overcurrent protection that limits inductor current during startup inrush. The 1A peak totem-pole output drives N-channel MOSFET gates directly, and the 2%-accurate 5V reference supports tight output voltage accuracy across load and temperature in battery-charging and LED driver front ends.
Recommended
Standby and Auxiliary Supplies
The UCC28C42DR's BiCMOS process delivers low startup and quiescent current, making it suitable for standby power stages that must meet energy-efficiency requirements. In these designs, the controller starts from a high-value bootstrap resistor, then the aux winding supplies the IC, so minimizing startup current directly reduces standby power draw. Designers typically set frequency via RT/CT at moderate levels (65-130 kHz) to trade switching losses against transformer size. Cycle-by-cycle current sense keeps fault current bounded during brownout events and output short conditions.
Recommended
Forward Converters
For medium-power forward converters in industrial and server aux supplies, the UCC28C42DR provides the peak current-mode control needed for tight transformer flux balance. Where 50% duty-cycle clamping is required to guarantee core reset, the pin-compatible UCC28C43DR or UCC28C44DR can be used on the same footprint. The 1A output stage rapidly discharges the MOSFET gate to minimize switching loss, and the 1000 kHz oscillator supports high-frequency designs that shrink magnetics. Standard 8-SOIC layout practices with short CS traces preserve current-sense accuracy.
Recommended
Recommended Products Summary
Engineering reference data for UCC28C42DR — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | UCC28C42QDRQ1 | UCC28C43DR | UCC38C42DR | UC3842ADR |
|---|---|---|---|---|---|
| Package | 8-SOIC (D) | 8-SOIC (D) - same | 8-SOIC (D) - same | 8-SOIC (D) - same | 8-SOIC (D) - same |
| Brand | Texas Instruments | Texas Instruments | Texas Instruments | Texas Instruments | Texas Instruments |
| UVLO On/Off | 14.5 V / 9 V | 14.5 V / 9 V | 8.4 V / 7.6 V | 14.5 V / 9 V | 16 V / 10 V |
| Max Duty Cycle | 100% | 100% | 50% | 100% | 100% |
| Max Frequency | 1000 kHz | 1000 kHz | 1000 kHz | 1000 kHz | 500 kHz |
| Peak Output Current | 1 A | 1 A | 1 A | 1 A | 1 A |
| Technology | BiCMOS | BiCMOS | BiCMOS | BiCMOS | Bipolar |
| Temperature Range | -40C to +85C | -40C to +125C (automotive) | -40C to +85C | 0C to +70C | -40C to +85C |
| Qualification | Industrial | AEC-Q100 Q1 | Industrial | Commercial | Industrial |
Key Differentiators
- 100% duty cycle capability (vs UCC28C43DR)
- BiCMOS low power consumption (vs UC3842ADR)
- Industrial temperature range standard (vs UCC38C42DR)
Design Notes
Keep the current-sense (CS) trace short and route it away from the gate-drive (OUT) trace to avoid false triggering from gate current transients. Use a small RC filter (e.g., 100 ohm / 100 pF) on CS if leading-edge spikes cause premature termination. Place RT/CT timing components close to pin 4, and ground them to a quiet analog ground point near pin 5.
Add at least 0.1uF ceramic bypass capacitance directly at VCC (pin 7) to GND, plus 10uF bulk if the aux winding is far away. Startup via bootstrap resistor: the resistor value must supply less than the startup current at minimum line voltage while allowing VCC to reach 14.5V. Verify the aux winding keeps VCC above 9V UVLO-off at all loads including light-load skip conditions.
Do not confuse family UVLO variants: the UCC28C42 (14.5V/9V) will not start from low-voltage aux rails designed for UCC28C43 (8.4V/7.6V). Also, VREF (pin 8) is a 5V output, not a supply input - connecting it to a source will damage the part. Maximum VCC is 20V; clamp transients on poorly regulated aux windings with a zener.
Compliance Information
RoHS compliant per distributor listings. For AEC-Q100 automotive use, select UCC28C42QDRQ1 instead.
