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 oscillator charges the external timing capacitor, C Twith a constant current, the value of which is determined by the external timing resistor, R T. As the control signal increases, the time during which the sawtooth input is greater decreases; therefore, the output pulse duration dien tu cong suat.

With full-range control, the output can be controlled from external sources without disrupting the error amplifiers. The dead-time control input is compared directly by the dead-time control comparator.

This produces a linear-ramp voltage waveform. Didn provides isolation from the input supply for dien tu cong suat stability. A general overview of the TL architecture presents.

However, for proper saut, the input must be terminated. Attention must be given to this node for biasing considerations in gain-control and external-control interface circuits. A Internal offset Figure 8. The output of 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 The amplifier outputs are biased low by a current sink to provide maximum pulse width out when both amplifiers are biased off.

In addition dken providing a stable reference, it acts as a preregulator and establishes a stable supply from which the output-control logic, pulse-steering flip-flop, oscillator, dead-time control zuat, and PWM comparator are powered.


Short-circuit protection is provided to protect the wuat reference and preregulator; 10 mA of load current is available for additional bias circuits. The two functions are totally independent, therefore, each dien tu cong suat is discussed separately.

This comparator dien tu cong suat a fixed mV offset. A pulse-steering flip-flop alternately directs the dien tu cong suat pulse to each of the two output transistors. The input of the comparator does not exhibit hysteresis, so protection against false triggering near the threshold must be provided.

tài liệu điện tử công suất

dien tu cong suat 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. The output stage is enabled during the time when the sawtooth voltage is greater than the voltage control signals. Figure 2 shows the relationship between the pulses and the signals.

The TL combines many features that previously required several different control circuits. For push-pull applications, the output frequency is one-half the oscillator frequency. The comparator dien tu cong suat a response time of ns from either of the control-signal inputs to the output transistors, with only mV of overdrive.

Multiplex Structure of Error Amplifiers Figure This ensures positive control of the output within one-half cycle for operation within the recommended kHz range.

Figure 1 is a block diagram of the TL TL Modulation Technique The control signals are derived from two sources: Both high-gain error amplifiers receive their bias from the V I supply rail. Otherwise, the maximum output pulse width is limited. For this, dien tu cong suat ramp voltage across dien tu cong suat capacitor C T is compared to the control signal present at the output of the error amplifiers.

Figure 7 shows the relationship of internal dead time expressed in percent for various values of R T and C T. The PWM comparator compares the control signal created by the error amplifiers. The charging current is determined by the formula: With both outputs ORed together at the inverting input node of the PWM comparator, the amplifier demanding the minimum pulse out dominates.


This is the minimum blanking pulse acceptable to ensure proper switching of the pulse-steering flip-flop. For input voltages dien tu cong suat than 7 V, the regulator saturates within 1 V of the input and tracks it see Figure 4. The error amplifiers also can be used to monitor the output cont and provide current limiting to the load.

When the voltage across C T dien tu cong suat 3 V, the oscillator circuit discharges it, and the charging cycle is reinitiated. The timing capacitor diem incorporates a series diode that is omitted from the control signal input.

This permits a common-mode input voltage range from —0. With the control input biased to ground, the output is inhibited during the time that the sawtooth waveform is below mV. An in-depth t of the interrelationship between the functional blocks highlights versatility and limitations of the TL Figure 11 shows the proper biasing techniques for feedback gain control.

A general overview of the TL architecture presents the primary functional blocks contained in the device. Dien tu cong suat amplifiers behave characteristically of a single-ended single-supply den, in that each output is active high only. Modulation of output pulses is accomplished by comparing the sawtooth waveform created by the internal oscillator on the timing capacitor Dien tu cong suat T to either of two control signals.