Part Number: UCC28950PWR

Manufacturer: Texas Instruments


Shipped from: Shenzhen/HK Warehouse

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Technical Specifications of UCC28950PWR

Datasheet  UCC28950PWR datasheet
Category Integrated Circuits (ICs)
Family PMIC – Voltage Regulators – DC DC Switching Controllers
Manufacturer Texas Instruments
Packaging Cut Tape (CT)
Part Status Active
Output Type Transistor Driver
Function Step-Up/Step-Down
Output Configuration Positive
Topology Full-Bridge
Number of Outputs 6
Output Phases 1
Voltage – Supply (Vcc/Vdd) 8 V ~ 17 V
Frequency – Switching 50kHz ~ 1MHz
Duty Cycle (Max) 95%
Synchronous Rectifier Yes
Clock Sync Yes
Serial Interfaces
Control Features Dead Time Control, Enable, Frequency Control, Soft Start
Operating Temperature -40°C ~ 125°C (TJ)
Package / Case 24-TSSOP (0.173″, 4.40mm Width)
Supplier Device Package 24-TSSOP

UCC28950PWR Description

The UCx895 phase-shifted controller family from Texas Instruments is the foundation for the UCC28950 improved phase-shifted controller, which is the industry standard. It adds improvements that make it the most efficient controller in its class for high-performance power systems today. The UCC28950 has advanced control over the full bridge and active control over the output stage of the synchronous rectifier. The signals on the primary side can be used to set delays that allow ZVS operation over a wide range of load current and input voltage. Meanwhile, the load current automatically tunes the switching delays on the secondary side of synchronous rectifiers, making the whole system as efficient as possible.

The UCC28950 also has several features for managing light loads, such as burst mode and dynamic SR on/off control when going into and out of the Discontinuous Current Mode operation. This lets ZVS operations continue with much lighter loads. The UCC28950 also lets you choose between controlling the current or the voltage. It has a programmable switching frequency of up to 1 MHz and many safety features, such as current limit by cycle, UVLO, and thermal shutdown. Setting up a 90-degree phase-shifted interleaved synchronized operation between two converters is easy. The UCC28950 comes in a package called TSSOP-24.

UCC28950PWR Features

  • Average or Peak Voltage Mode Control and Current Mode Control with Programmable Slope Compensation.
  • With DCM Mode, starting up with a pre-biased signal is easy.
  • Soft Start and Enable Function for Closed Loop.
  • Programmable Up to 1 MHz switching frequency with bidirectional synchronization (3%). Current Limit Protection on a Cycle-by-Cycle Basis with Support for Hiccup Mode.
  • Start-up current of 150 mA.
  • VDD Undervoltage Lockout.
  • –40°C to +125°C is a wide range of temperatures.

UCC28950PWR Applications

  • Phase-Shifted Full-Bridge Converters.
  • Server, Power Supplies.
  • High-Density Power Architectures.

Detailed Description

The UCC28950 is a 24-pin TSSOP package with all the parts needed to run a phase-shifted full-bridge power stage. The device has the outputs to drive all four switches in a full-bridge circuit. It also has two outputs for driving the gates of synchronous rectifiers (SR). The DELAB and DELCD inputs control the time that goes by between the top and bottom switches of the bridge.

Also, the ADEL pin lets this dead time be changed in real-time to match changes in load. Because of this, the customer can adjust the dead time to fit the needs of their power circuit and still get ZVS everywhere. Changing the DELEF input allows both the full bridge switches and the secondary SRs to optimize their dead times. By changing the ADELEF controller input, this dead time can be changed in real time based on the load.

DCM, “Discontinuous Conduction Mode,” lets users turn off the SRs when the load is low. Because of this, the power circuit will work better. If the feedback loop needs a conduction time shorter than a level the user can set, the device goes into a light-load burst mode (TMIN). It is easy to get two or more UCC28950 devices to work together at higher power levels in a Master/Slave configuration. The SS/EN input can set the soft start time and turn the controller on or off. The controller can be used with both voltage and current modes. In the Voltage and Peak Current modes, the current can be changed from one cycle to the next. Because this device’s switching frequency can be changed, it can be used in a number of IGBT and MOSFET designs.

Feature Description

● Burst Mode

The converter will cause the controller to enter Burst Mode if it requests a duty cycle less than TMIN. The controller will always distribute an even number of power cycles to the power transformer. Bursts are always terminated by an OUTC and an OUTB power delivery cycle by the controller. The controller enters shutdown mode if it continues to request a duty cycle that is less than TMIN. The controller then sends out TMIN or a PWM duty cycle based on the COMP voltage pin after waiting until the converter requests a duty cycle equal to or higher than TMIN.

● Supply Voltage (VDD)

Connect a bias voltage source between 8 V and 17 V to this pin. To connect this pin to the ground, you must put a high-quality, low-ESR, and low-ESL ceramic bypass capacitor of at least 1 F here. You can make an RC filter by connecting a 10-ohm resistor and the CVDD capacitor from the bias supply to the VDD pin.

● Ground (GND)

When you’re at this node, you’re at the epicenter of everything. The power plane and the analog plane should be connected in a single, quiet location. Connecting the analog plane components are the pins VREF, EA+, SS/EN, EA-, COMP, DELEF, DELAB, DELCD, TMIN, RT, and RSUM. Connecting components on the power plane can be accomplished using the pins labeled DCM, ADELEF, OUTB, ADEL, CS, OUTF, SYNC, OUTD, OUTE, OUTC, OUTA, and VD.

Application Information

Phase-shifted full-bridge DC/DC converters based on the UCC28950 are very efficient because they use synchronous rectification, a control algorithm that provides ZVS condition over the entire load current range, precise adaptive timing of the control signals between the primary and secondary FETs, and different operating modes at light load.

Even though it might be on the primary side of the converter, the controller is connected to its secondary output. Because the synchronous rectifier MOSFETs are on the secondary side, they can be controlled quickly and precisely in situations where it would be hard to do so otherwise, such as when the voltage changes quickly. The power stage has the QA, QB, QC, and QD MOSFETs on the primary side. On the secondary side, it has the QE and QF synchronous rectifier MOSFETs. In 12-V output converters for servers, center-tapped rectifier schemes with L-C output filters are often used.

The converter runs in synchronous rectification mode at moderate and high output powers, diode rectifier mode at light loads, and burst mode at very low powers to maintain high efficiency in different situations. These changes depend on how much current flows through the transformer’s primary windings, measured by a current-sense transformer.


In conclusion, the Texas Instruments UCC28950PWR soft switching PWM controller is a great tool for managing power that can help your project run better. It uses less power because it uses soft switching. It also only has one output with a voltage of 5V, which makes it perfect for power management. It has a switching regulator with a high frequency of 1000 kHz, which makes it easy to manage power. It can handle high-power applications while staying stable because its maximum duty cycle is 97%.

This part is packaged on a tape and reel for your convenience. This makes it easy to ship and mount. It can work from -40 °C to 125 °C and can be used in many places. If you want a reliable distributor in China, ICRFQ can provide high-quality electronic parts like the UCC28950PWR soft switching PWM controller and support.

So, if you want your project to work better, don’t miss out on the chance to use this great tool. Get in touch with us at ICRFQ right away to learn more and get started. Let us help you finish your project.

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