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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All other mode boundaries are preset with the thresholds in ucf28600d oscillator and green-mode blocks. When the load increases, the peak current increases and the ucc28600d datasheet frequency decreases.
This allows the UCC to monitor the FB voltage to determine and respond to the varying load levels such as heavy, light or ultra-light. As the load decreases from its designed maximum output power, the UCC will demand ucc28600d datasheet higher ucc28600d datasheet frequency and decreased peak current. In this mode, the flyback converter operates at the boundary of discontinuous conduction mode and continuous conduction mode.
Refer to the Functional Block DiagramTypical Application DiagramFigure 6 ucc28600d datasheet, Figure 7Figure 8Figure 10Dataeheet 11and Figure 12 for detailed block descriptions that show how the features are integrated into the normal control functions. In turn, the peak CS voltage is commanded to be between 0. This ucc28600d datasheet is used to control bias power for a PFC stage, as shown in Figure 9.
8-Pin Quasi Resonant Flyback Green Mode Controller
It prevents operation when ucc28600d datasheet internal reference is below 4. Thus during cycle-by-cycle power limit, the peak CS voltage is typically 0.
It also has a minimum frequency clamp of 40 kHz.
When the bias winding is positive, during demagnetization or portions of the resonant ring, the OVP pin voltage is positive. By adjusting both the peak current and the switching frequency, the output power ucc28600d datasheet adjusted to match the load requirement.
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Effectively, operation in FFM results ucc28600d datasheet the application of constant volt-seconds to the flyback ucc28600d datasheet each switching cycle. At this maximum switching frequency, the converter enters DCM control. Keep in mind that the aforementioned boundaries of steady-state operation are approximate because they are ucc28600d datasheet to dagasheet design parameters. Datashert a lesser degree yet significantthe boundaries are affected by the MOSFET output capacitance and transformer leakage inductance.
In this mode, the flyback converter ucc28600d datasheet always operate in discontinuous conduction mode. 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 greater than the f QR min over the entire ucc28600d datasheet operating range.
A cycle-by-cycle power limit imposes ucc28600d datasheet dwtasheet 0. This current source adds a proportional step fatasheet power limit offset to the CS signal and is part of the cycle-by-cycle power limit function that is discussed in the Protection Features section. Operation in FFM results in the application of constant volt-seconds to the flyback transformer during each switching cycle.
Valley detection is active during FFM. An overcurrent shutdown threshold in the fault logic gives added protection against high-current, slew-rate shorted winding faults, ucc28600d datasheet in Figure 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 power limit function can be programmed by a resistor, R PLthat is between the CS pin and the current sense resistor.
The details of the functional boxes also conceptualize the various fault detections and responses that are included in the UCC Ucc28600d datasheet VDD is the greater of: During green mode, the converter operates at a fixed switching frequency ucc28600d datasheet 40 kHz and fixed peak current. In QRM, the switching frequency will decrease as the load increases; DCM operation is at the clamped maximum switching ucc28600d datasheet kHz.
The mode of operation depends upon line and load conditions. When the FB voltage is between 1. If the OVP voltage is greater ucc28600d datasheet 3. Ucc28600d datasheet soft start, the converter switching frequency is fixed at 40 ucc28600d datasheet and FB is set to 5V. At power limit, the CS pin voltage plus the internal CS offset is compared against a constant 1. At DCM control, the peak current is adjusted to control the output power. If the FB voltage tries to drive operation to less than 40 kHz, the converter operates in green mode.
The controller will operate in burst mode operation, or green mode GM driving the primary side MOSFET with packets of kHz pulses, at fixed peak primary current for light-load conditions. Ucc288600d proper amount of additional voltage has the effect of limiting the power on a cycle-by-cycle basis.