17 Tháng Tám 12/11/09 PM Page ii Commonly used Power and Converter Equations Instantaneous power: p(t) ϭ v(t)i(t) t2 Energy: W. 13 Tháng Năm Voltage Regulators With the TL Patrick Griffith Standard Linear and Logic ABSTRACT The TL power-supply controller is discussed in. Công ty cổ phần Entertech Việt nam. Bảng điện tử sản xuất LED · BẢNG ĐIỆN TỬ LED đ. Bảng thông tin sản xuất tactime cho nhà máy cơ khí đ.
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The PWM comparator compares the control signal created by the error amplifiers. A general overview of the TL architecture presents.
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The amplifier outputs are biased low by a current sink to provide maximum pulse width out when both amplifiers are biased off. However, for proper control, the input must be terminated.
TL Modulation Technique The control signals are derived from two dien tu cong suat The charging current is determined by the formula: For input voltages less than 7 V, the regulator saturates within 1 V of the input and tracks it see Figure 4. Figure 7 shows dien tu cong suat relationship of internal dead time expressed in percent for various values of R T and C T.
This provides isolation from the input supply for improved stability. The output stage is enabled during the time when the sawtooth voltage is greater than the voltage control signals. The input of the comparator does not exhibit hysteresis, so protection against false triggering near the threshold must be provided.
The purpose of this application report is to give the reader a thorough understanding of the TL, its features, its performance characteristics, and its limitations. Figure 11 shows the proper biasing techniques for feedback gain control. This produces a linear-ramp dien tu cong suat waveform. An open circuit is an undefined condition. Otherwise, the maximum output pulse width is sjat.
With both outputs ORed together at the inverting input node of the PWM comparator, the amplifier demanding the minimum pulse out dominates. This comparator has a fixed mV offset.
The error amplifiers also can be used to monitor the output suqt and provide current limiting to the load. The oscillator provides a positive sawtooth waveform to the dead-time and PWM comparators for comparison to the various control signals.
For this, the ramp voltage across timing capacitor C T is compared to the dien tu cong suat signal present at the output of the error amplifiers.
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dien tu cong suat Both amplifiers behave characteristically of a single-ended single-supply amplifier, in that each output is active high only. Short-circuit protection is provided to protect the internal reference and preregulator; 10 mA of load current is available for additional bias circuits. Modulation of output pulses is accomplished by comparing the sawtooth waveform created by the internal oscillator on the timing capacitor C T to either of two control signals.
The TL combines many features that previously required several suay control circuits.
Attention must be given to this node for biasing considerations in gain-control and external-control interface circuits. The oscillator charges the external timing capacitor, C Twith a constant current, the value of which is determined by the dien tu cong suat timing resistor, R T.
Both high-gain error amplifiers receive their bias from the V I supply rail. A Internal offset Figure 8.
A pulse-steering flip-flop alternately directs the modulated pulse to each of the two output transistors. This ensures positive dien tu cong suat of the output within one-half cycle for operation within the recommended kHz range.
This allows each amplifier to pull up independently for a decreasing output pulse-width demand. Figure 1 is a block diagram of the TL Reference Voltage vs Input Voltage 3. The timing capacitor input incorporates a series diode that is omitted from the control signal input.
This is the minimum blanking pulse acceptable to ensure proper switching of the pulse-steering flip-flop. The output dien tu cong suat the comparator inhibits switching transistors Q1 and Q2 when the voltage at the input is greater than the ramp voltage of the oscillator see Figure For push-pull applications, the output frequency is one-half the oscillator frequency.