UCCD PDF datasheet & technical specifications. Download or read online TI (Texas Instruments) UCCD IC CTRLR PWM GREEN CM OVP 8SOIC. The UCC is a PWM controller with advanced Texas Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet. Texas Instruments UCCD: available from 21 distributors. Explore Integrated Circuits (ICs) on Octopart: the fastest source for datasheets, pricing.

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Protection is provided to guard against operation during unfavorable bias conditions. During all modes of operation, this controller ucc28600d datasheet in current mode control.

Depending upon the line and load conditions, the UCC controls the converter using different modes of operation, which are defined as quasi-resonant QR modediscontinuous conduction mode DCMfrequency foldback mode FFM and green mode GMdetermined by the voltage on the Ucc28600d datasheet pin, as shown in Figure ucc28600d datasheet It also has a minimum frequency clamp of 40 kHz.

The details of the functional boxes also conceptualize the various fault detections and responses that are included ucc28600d datasheet the UCC In turn, the peak CS voltage is commanded to be between 0. At power limit, ucc28600s CS pin voltage plus ucc28600d datasheet internal CS offset is compared against a constant 1. It prevents operation when the internal reference is below 4. During green mode, the converter operates at a fixed switching ucf28600d of 40 kHz ucc2800d fixed peak current. At DCM control, the peak current is adjusted to control the output power.

These figures conceptualize how the UCC executes the command of the FB voltage to have the responses that are shown in Figure 11Figure 5 and Figure The controller will operate in burst mode operation, or green mode GM driving the primary side Ucc28600d datasheet with packets of kHz pulses, at fixed peak primary current for light-load conditions.

Advanced logic control coordinates the fault detections to provide proper power supply recovery. If the OVP voltage is greater than 3. Operation in FFM ucc28600d datasheet in the application ucc28600d datasheet constant volt-seconds to the flyback transformer during each switching cycle. Resonant valley switching is an integral part of QR operation.

Ucc28600d datasheet mode reduces the average switching frequency in order to minimize switching losses and increase the efficiency at light-load conditions.


Slight frequency dithering between resonant valleys will occur as the valley detection is active in DCM control.

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The transformer characteristics that predominantly affect the modes are the magnetizing inductance of the primary and the magnitude of the ucc28600d datasheet voltage, reflected to the primary. Operation Mode Switching Frequencies. If the FB voltage tries to drive operation to less than 40 satasheet, the converter operates in green mode. To a lesser degree yet significantthe boundaries are affected by the MOSFET output capacitance and transformer leakage inductance.

This current source adds a proportional step offset power limit offset to the CS signal and is part of the cycle-by-cycle power limit function that is ucc28600d datasheet in the Ucc28600d datasheet Features section. When the FB voltage is between 1. When the load increases, the peak current increases and the switching frequency decreases. An overcurrent shutdown threshold in the fault logic gives added datashewt against high-current, slew-rate shorted winding faults, shown in Figure In this mode, the converter operates in hysteretic control with the OUT pulse terminated at a fixed CS voltage level of 0.

Soft-start ucc28600d datasheet fault responses are the exception. Ucc28600d datasheet turn, the CS voltage is commanded to be between 0. When the bias winding is positive, during datasheett or dahasheet of the resonant ring, the OVP pin voltage is positive.

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The oscillator, shown in Figure 8is ucc28600d datasheet set and trimmed so it is clamped by the circuit in Figure 8 to a nominal kHz maximum operating frequency. The actual inductance should be noticeably smaller to account for the ring between the magnetizing inductance and the total stray capacitance measured at the drain of the ucc28600d datasheet MOSFET.

During frequency foldback mode, as the load decreases, the MOSFET peak current is kept constant and the switching frequency is reduced foldback to reduce the output power. During this control mode, the rising edge of OUT will occur just after the valley of the resonant ring ucc28600d datasheet the transformer is fully demagnetized.

Retry is allowed if the substrate temperature reduces by the hysteresis value.

UCCD 데이터시트(PDF) – Texas Instruments

As the load increases, the number of pulses in these burst packets increases until the converter is switching consistently at 40 kHz, at which point it transitions into the next operating mode, called ucc28600d datasheet foldback. The use datashet the UCC design calculator, SLVCis highly recommended in ucc28600d to achieve the ucc28600d datasheet results with a careful balance between the transformer parameters and the programming resistors.


Keep in mind that the aforementioned boundaries of steady-state operation are approximate because they are subject to converter design parameters.

Refer to the Functional Block DiagramTypical Application DiagramFigure 6 ucc28600d datasheet, Figure 7Figure 8Figure dataeheetUxc28600d 11and Figure 12 for detailed block descriptions that show how the features are integrated into ucd28600d normal control functions. Ucc28600d datasheet detection is active during FFM. During soft start, the converter switching frequency is fixed at 40 kHz and FB is set to 5V. This pin is used to control bias power for a PFC stage, as shown in Figure 9.

In this mode, the flyback converter operates at the boundary of discontinuous conduction mode and continuous conduction mode. C VDD is the greater of: When FB reaches ucc28600d datasheet.

In this mode, the flyback converter will always operate in discontinuous conduction mode. A cycle-by-cycle power limit imposes a fixed 0. ucc28600d datasheet

Voltage regulation in Ucc28600d datasheet is achieved by varying the switching frequency in the range from kHz to 40 kHz. The UCC has many protection features that are found only on larger, full featured controllers. The proper amount of additional voltage has the effect of limiting the power on a cycle-by-cycle ucc28600d datasheet. At this maximum switching frequency, the converter enters DCM control.

In order to have power limited over the full line voltage range of the QR Flyback ucc28600d datasheet, the CS pin voltage must have a component that is proportional to the primary ucc28600d datasheet plus a component that is proportional to the line voltage due to predictable switching frequency variations due to line voltage. As the load decreases from its designed maximum output power, the UCC will demand a higher switching frequency and decreased peak current.

The transformer magnetizing inductor value has to be designed accordingly so that the converter can deliver the maximum required power while maintaining a switching frequency that is ucc28600d datasheet than the f QR min over the entire input operating range. By adjusting both the peak current and the switching frequency, ucc28600d datasheet output power is adjusted to match the load requirement.