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參數(shù)資料
| 型號： | TL5001MFK |
| 廠商： | Texas Instruments, Inc. |
| 英文描述： | PULSE-WIDTH-MODULATION CONTROL CIRCUITS |
| 中文描述： | 脈寬調(diào)制控制電路 |
| 文件頁數(shù)： | 3/23頁 |
| 文件大?。?/td> | 348K |
| 代理商： | TL5001MFK |
TL5001, TL5001A
PULSE-WIDTH-MODULATION CONTROL CIRCUITS
SLVS084E – APRIL 1994 – REVISED OCTOBER 1999
3
POST OFFICE BOX 655303
DALLAS, TEXAS 75265
detailed description
voltage reference
A 2.5-V regulator operating from V
CC
is used to power the internal circuitry of the TL5001 and TL5001A and
as a reference for the error amplifier and SCP circuits. A resistive divider provides a 1-V reference for the error
amplifier noninverting input which typically is within 2% of nominal over the operating temperature range.
error amplifier
The error amplifier compares a sample of the dc-to-dc converter output voltage to the 1-V reference and
generates an error signal for the PWM comparator. The dc-to-dc converter output voltage is set by selecting
the error-amplifier gain (see Figure 1), using the following expression:
V
O
= (1 + R1/R2) (1 V)
To PWM
Comparator
Vref = 1 V
4
VI(FB)
3
+
–
R2
R1
COMP
FB
Compensation
Network
TL5001/A
GND
8
Figure 1. Error-Amplifier Gain Setting
The error-amplifier output is brought out as COMP for use in compensating the dc-to-dc converter control loop
for stability. Because the amplifier can only source 45
μ
A, the total dc load resistance should be 100 k
or more.
oscillator/PWM
The oscillator frequency (f
osc
) can be set between 20 kHz and 500 kHz by connecting a resistor between RT
and GND. Acceptable resistor values range from 15 k
to 250 k
. The oscillator frequency can be determined
by using the graph shown in Figure 5.
The oscillator output is a triangular wave with a minimum value of approximately 0.7 V and a maximum value
of approximately 1.3 V. The PWM comparator compares the error-amplifier output voltage and the DTC input
voltage to the triangular wave and turns the output transistor off whenever the triangular wave is greater than
the lesser of the two inputs.
dead-time control (DTC)
DTC provides a means of limiting the output-switch duty cycle to a value less than 100%, which is critical for
boost and flyback converters. A current source generates a reference current (I
DT
) at DTC that is nominally
equal to the current at the oscillator timing terminal, RT. Connecting a resistor between DTC and GND generates
a dead-time reference voltage (V
DT
), which the PWM/DTC comparator compares to the oscillator triangle wave
as described in the previous section. Nominally, the maximum duty cycle is 0% when V
DT
is 0.7 V or less and
100% when V
DT
is 1.3 V or greater. Because the triangle wave amplitude is a function of frequency and the
source impedance of RT is relatively high (1250
), choosing R
DT
for a specific maximum duty cycle, D, is
accomplished using the following equation and the voltage limits for the frequency in question as found in
Figure 11 (V
osc
max and V
osc
min are the maximum and minimum oscillator levels):
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相關代理商/技術參數(shù) |
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|---|---|
| TL5001MFKB | 制造商:TI 制造商全稱:Texas Instruments 功能描述:PULSE-WIDTH-MODULATION CONTROL CIRCUITS |
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| TL5001MJGB | 制造商:Texas Instruments 功能描述:DC DC Cntrlr Single-OUT PWM DC to DC Controller 3.6V to 40V Input 8-Pin CDIP |
| TL5001P | 制造商:TI 制造商全稱:Texas Instruments 功能描述:PULSE-WIDTH-MODULATION CONTROL CIRCUITS |
| TL5001PS-M | 制造商:Texas Instruments 功能描述: |
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