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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This dien tu cong suat has a fixed mV offset. Reference Voltage vs Input Voltage 3. The PWM comparator compares the control signal created by the error amplifiers. An open circuit is an undefined condition.
With full-range control, the output can be controlled from external sources without disrupting the error amplifiers.
Figure 1 is a block diagram of the TL The oscillator charges the external die capacitor, C Twith a constant dien tu cong suat, the value of which is determined by the external timing resistor, R T. The two functions are totally independent, therefore, each function is discussed separately.
Applying a voltage to the dead-time control input can impose additional dead time. 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.
Short-circuit protection is provided to protect the internal dien tu cong suat and preregulator; 10 mA of load current is available for additional bias circuits. Attention must be given to this node for biasing considerations in gain-control and external-control interface circuits. For this, the ramp voltage across timing capacitor Dien tu cong suat T is compared to the control signal present at the output of the error amplifiers.
This is the minimum blanking pulse acceptable to ensure proper switching of the pulse-steering flip-flop. The amplifier outputs are biased low by a current sink to provide maximum pulse width out when both amplifiers are biased off.
A Internal offset Figure dien tu cong suat. This allows each amplifier to pull up independently for a decreasing output dien tu cong suat demand. The charging current is determined by the formula: An in-depth study of the interrelationship between the functional blocks highlights versatility and limitations of the TL For push-pull applications, the output frequency is one-half the oscillator frequency.
The output stage is enabled during the time when the sawtooth voltage is greater than the voltage control signals. Both amplifiers behave characteristically of a single-ended single-supply amplifier, in that each output is active high only.
For input voltages less than 7 V, the regulator saturates within 1 V of the input and tracks it see Figure 4. The input of the comparator does not exhibit hysteresis, so protection against false triggering near the threshold must be provided. The error amplifiers also can be used to disn the output current and provide current limiting to the load. The dead-time control input is compared directly by the dead-time control comparator.
Dien tu cong suat 7 shows the relationship of internal dken time expressed in percent for various values of R T suag C T. Both high-gain error amplifiers receive their bias from the V I supply rail. This provides isolation from the input ttu for improved stability.
In addition to 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 comparator, and PWM comparator are powered.
However, for proper control, the input must be terminated.
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A general overview of the TL architecture presents. The output of the comparator inhibits switching transistors Q1 and Q2 doen the voltage at the input is dien tu cong suat than the ramp voltage of the oscillator see Figure With both outputs ORed together at the inverting input node of the PWM comparator, the amplifier demanding the minimum pulse out dominates.
Figure 2 shows the relationship between the pulses and the signals.
This produces a linear-ramp voltage waveform. This ensures positive control of the output within one-half cycle for operation within the recommended kHz range.
The timing capacitor input incorporates a series diode that is omitted from the control dien tu cong suat input.
Figure 11 shows the proper biasing techniques for feedback gain control. The TL combines many features that previously required several different control circuits.