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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When the bias winding is positive, during demagnetization or portions of the resonant ring, the OVP pin voltage ucf28600d positive. This current source adds a proportional step offset power limit offset to the CS signal and is part ucc28600d datasheet the cycle-by-cycle power limit function ucc28600d datasheet is discussed in the Protection Features section.
As the load increases, the kHz switching will become consistent and the ucc28600d datasheet will transition to frequency fold-back mode FFMwhere the peak primary current is held constant and the switching frequency is modulated from 40 kHz up to kHz, in order to maintain regulation. To a lesser degree yet significantthe boundaries are affected by the Ucc28600d datasheet output capacitance and transformer leakage inductance.
During ucc28600d datasheet 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. Keep in mind that the aforementioned boundaries of steady-state operation are approximate because they are subject to converter design parameters. It also has a minimum frequency clamp of 40 kHz.
CS 3 I Equation 1.
The actual inductance should be noticeably smaller to ucc28600d datasheet for the ring between the magnetizing inductance and the total stray capacitance measured at the drain of the ucc28600d datasheet MOSFET. The oscillator, shown in Figure 8is internally set and trimmed so it is clamped by the circuit in Figure 8 to a nominal kHz maximum operating frequency.
In turn, the CS voltage is commanded to be between 0. Soft-start and fault dqtasheet ucc28600d datasheet the exception. Under normal operating conditions, the FB pin commands the operating mode of the UCC at the voltage thresholds shown ucc28600d the control flow chart, Figure C VDD is the greater of: The power limit function can be programmed by a resistor, R PLthat is between the CS pin and the current sense resistor.
In this mode, the flyback converter will always operate in discontinuous conduction mode. When the dayasheet current ucc28600d datasheet maximum current level which is indicated by ucc28600d datasheet voltage of 1. If the OVP voltage is greater than 3.
During this control mode, the rising edge of OUT will occur just after the valley of the resonant ring when the transformer is fully demagnetized. Slight frequency dithering between resonant valleys will occur as the valley detection is active ucc28600d datasheet DCM control. Line over voltage protection occurs ucc28600d datasheet the OVP pin is clamped at 0 V. At DCM control, the peak current is adjusted to control the output power.
The transformer magnetizing inductor value ucc28600d datasheet to be designed accordingly so that the converter can deliver the maximum required power while ucc28600d datasheet a switching frequency that is greater than the f QR min over the entire input operating range.
In QRM, the switching frequency will decrease as the load increases; DCM operation is at the clamped maximum switching frequency kHz.
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At higher loads, the UCC will operate in either DCM, where the peak primary current is modulated but the switching frequency is uucc28600d at ucc28600d datasheet maximum value, or quasi-resonant mode QRMwhere the switching frequency and the uvc28600d primary current are both modulated in ucc28600d datasheet to maintain regulation.
Refer to the Functional Block DiagramTypical Application DiagramFigure 6Figure 7Figure 8Figure 10Figure 11and Figure 12 for detailed adtasheet descriptions that show how the features are integrated into the normal control functions. Because the device will initiate cycle-by-cycle power limit first, primary side current protection is not intended to protect against output short circuit conditions.
The proper amount of additional voltage has the effect of limiting the ucc28600d datasheet on a cycle-by-cycle basis. By ucc28600d datasheet both the peak current and the switching frequency, the output power is adjusted to datasyeet the load requirement.
In order to have power limited over the full line voltage range of the QR Flyback converter, ucc28600d datasheet CS pin voltage must have a component that is proportional to the primary current plus a component that is proportional to the line voltage due to predictable switching frequency variations due to line voltage. When the load increases, the peak current increases and the switching ucf28600d decreases. This allows the UCC to monitor the FB voltage to ucc28600d datasheet and respond to the varying load levels such as heavy, light or ultra-light.
The use of ucc28600d datasheet UCC design calculator, SLVCis highly recommended in order to achieve the desired results with a careful balance between datasheeg transformer parameters and the programming resistors. All other mode boundaries are preset with the thresholds in the oscillator and green-mode blocks.
During all modes of operation, this controller operates ucc28600d datasheet current mode control.
Texas Instruments UCC28600 for Smart Metering Power Supply Applications
Resistor R PL jcc28600d in the addition of a voltage to the current sense signal that is proportional datashedt the line voltage.
As the load increases, the number of pulses in these burst packets increases until the converter is switching consistently ucc28600d datasheet 40 kHz, at which point it transitions into ucc28600d datasheet next operating mode, called frequency foldback. If the FB voltage tries to drive operation to less than 40 kHz, the converter operates in green mode. This provides the conditioning for the thermal protection.
The UCC has many protection features that are found only on larger, full featured controllers. As the load decreases from its designed maximum output power, ucc28600d datasheet UCC will demand a higher switching frequency and decreased peak current.
The mode of operation ucc28600d datasheet upon line and load conditions. Resonant valley switching is an integral part of QR operation.