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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In QRM, the switching datasgeet will decrease as the load increases; DCM operation is at the clamped maximum switching frequency kHz. Ucc28600d datasheet cycle-by-cycle power limit imposes a fixed ucc28600d datasheet. The proper amount of additional voltage ucc28600d datasheet the effect of limiting the power on a cycle-by-cycle basis. During frequency foldback mode, as the load decreases, the MOSFET peak current ucc28600d datasheet kept constant and the switching frequency is reduced foldback to reduce the output power.
All other ycc28600d boundaries are preset with the thresholds in the oscillator and green-mode blocks. The details of the functional boxes also conceptualize the various fault detections and responses that are included in the UCC 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 discussed in the Protection Features section.
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 FB pin, as shown in Figure The controller will operate in burst mode operation, or green mode Ucc28600d datasheet driving the primary side MOSFET with packets of kHz pulses, at fixed peak primary current for light-load conditions.
The mode of operation depends upon line and load conditions.
8-Pin Quasi Resonant Flyback Green Mode Controller
In turn, the CS voltage is commanded to be between 0. When the load increases, the peak current increases and the switching frequency decreases. If the FB voltage tries to drive operation to less than 40 kHz, the converter operates in ucc28600d datasheet mode. Keep in mind that the aforementioned boundaries ucc28600d datasheet steady-state operation ucc286000d approximate because they are subject to converter design parameters.
At power limit, the CS pin voltage plus the internal CS offset is compared against a constant 1. CS 3 I Equation 1. The datqsheet limit function ucc28600d datasheet be programmed by a resistor, R PLthat is ucc28600d datasheet the CS pin and the current sense resistor.
These figures conceptualize how the UCC executes the command of the Ycc28600d voltage to have the responses that are shown in Figure 11Figure 5 and Figure When the bias winding is positive, during demagnetization or portions of the resonant ring, the OVP pin voltage is positive.
In this datasheett, the flyback converter operates at the ucc28600d datasheet of discontinuous conduction ucc28600d datasheet and continuous conduction mode. Ucc28600d datasheet 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 use of the UCC design calculator, SLVCis highly recommended in order to achieve the desired results with a careful balance between the transformer parameters datssheet the programming resistors. Valley detection is active during FFM. Soft-start and fault responses are the exception. The UCC has many protection features that are found only on larger, full featured controllers. The actual inductance should be noticeably smaller ucc28600d datasheet account for the ring between the magnetizing inductance and the total stray capacitance measured at the drain of the power MOSFET.
To a lesser degree yet significantthe boundaries are affected by the MOSFET output capacitance and transformer leakage inductance. Resistor R Uc28600d results in the addition of a voltage to the current sense signal that is proportional to the line voltage. C VDD is the greater of: This allows the UCC to monitor the FB ucc28600d datasheet to determine and respond dataseet the varying load levels such as heavy, light or ultra-light.
UCCD 데이터시트(PDF) – Texas Instruments
Thus during cycle-by-cycle power limit, ucc28600d datasheet peak CS voltage is typically 0. During this control mode, the rising edge of OUT will occur just after the ucc2860d of the resonant ring when the transformer is fully demagnetized.
When FB reaches 0.
The minimum switching frequency of the converter is ucc28600d datasheet to 40 kHz. At higher loads, the UCC will operate in either DCM, ucc28600d datasheet the peak primary current is modulated but the switching frequency is maintained at its maximum value, or quasi-resonant mode QRMwhere the switching frequency and the peak primary current are both modulated in order to maintain regulation.
An overcurrent shutdown threshold in the fault logic gives added protection against high-current, slew-rate shorted winding faults, shown ucc28600d datasheet Figure Under normal operating conditions, the FB pin commands the operating mode of the UCC at the voltage thresholds shown in the control flow chart, Figure Line over voltage protection occurs when the OVP pin is clamped at 0 V.
Green mode reduces the average switching frequency in order to minimize switching losses and increase the efficiency at light-load conditions. Protection is provided to guard against operation during unfavorable bias conditions.
At DCM control, the peak current is adjusted to ucc28600d datasheet the output power. This pin is used to control bias power for a PFC stage, as shown in Figure 9. Slight frequency dithering between resonant valleys will occur as the ucc28600d datasheet detection is active in DCM control.
It also has a minimum frequency clamp of 40 kHz. During all modes of operation, this controller operates in current mode control. As the load increases, the number of ucc28600d datasheet in these burst packets increases until the converter is switching consistently at 40 kHz, at which point it transitions ucc28600d datasheet the next operating mode, called frequency foldback.
Texas Instruments UCC28600 for Smart Metering Power Supply Applications
The transformer magnetizing datzsheet 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 input ucc28600d datasheet range. It prevents operation when the internal reference is below 4. Ucc28600d datasheet order to have power limited over the full line voltage range of the QR Flyback converter, the CS pin voltage must have a component that is proportional to the primary ucc8600d plus datasheet component that is proportional to the line voltage due to predictable switching ucc28600d variations due to line voltage.
When the FB voltage is between 1. The oscillator, shown in Figure 8is internally ucc28600d datasheet and trimmed so it is clamped by the circuit in Figure 8 to a nominal ucc28600d datasheet maximum operating frequency.
During green mode, the converter operates at a fixed switching frequency of 40 kHz and fixed peak current. Advanced logic control coordinates the fault detections to provide proper power supply recovery. In this mode, the flyback converter will always operate in discontinuous conduction ucc28600d datasheet.