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參數(shù)資料
| 型號： | UC1827 |
| 廠商： | Texas Instruments, Inc. |
| 英文描述： | Buck Current/Voltage Fed Push-Pull PWM Controllers |
| 中文描述： | 降壓電流/電壓美聯(lián)儲推挽式PWM控制器 |
| 文件頁數(shù)： | 7/15頁 |
| 文件大?。?/td> | 283K |
| 代理商： | UC1827 |
www.ti.com
APPLICATION INFORMATION
+
–
RT
CT
SYNC
S
R
V
REF
2.5 V
OSCILLATOR
V
REF
10 k
1.4 V
2.5 V
2.9 V
0.5 V
R
T
C
T
VDG99086
CIRCUIT BLOCK DESCRIPTION
PWM Oscillator
I
RT
2.5 V
R
RT
(1)
UC1827-1, UC1827-2
UC2827-1, UC2827-2
UC3827-1, UC3827-2
SLUS365A–APRIL 1999–REVISED AUGUST 2005
Figure 1. Oscillator Block With External Connections
The oscillator block diagram with external connections is shown in
Equation 1
. A resistor (R
T
) connected to pin
RT sets the linear charge current:
The timing capacitor (C
CT
) is linearly charged with the charge current forcing the OSC pin to charge to a 3.4 V
threshold. After exceeding this threshold, the RS flip-flop is set driving CLKSYN high and R
DEAD
low which
discharges C
CT
. CT continues to discharge until it reaches a 0.5 V threshold and resets the RS flip-flop which
repeats the charging sequence as shown in
Figure 2
As shown in
Figure 3
, several oscillators are synchronized to the highest free running frequency by connecting
100 pF capacitors in series with each CLKSYN pin and connecting the other side of the capacitors together
forming the CLKSYN bus. The CLKSYN bus is then pulled down to ground with a resistance of approximately
10k. Referring to
Figure 1
, the synchronization threshold is 1.4 V. The oscillator blanks any synchronization pulse
that occurs when OSC is below 2.5 V. This allows units, once they discharge below 2.5 V, to continue through
the current discharge and subsequent charge cycles whether or not other units on the CLKSYN bus are still
synchronizing. This requires the frequency of all free running oscillators to be within 17% of each other to assure
synchronization.
7
相關(guān)PDF資料 |
PDF描述 |
|---|---|
| UC1827- | Buck Current/Voltage Fed Push-Pull PWM Controllers |
| UC1827-2 | Buck Current/Voltage Fed Push-Pull PWM Controllers |
| UC1827J-2 | Buck Current/Voltage Fed Push-Pull PWM Controllers |
| UC3827 | Buck Current/Voltage Fed Push-Pull PWM Controllers |
| UC2845AJ | OMNIFET II: FULLY AUTOPROTECTED POWER MOSFET |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| UC1827- | 制造商:TI 制造商全稱:Texas Instruments 功能描述:Buck Current/Voltage Fed Push-Pull PWM Controllers |
| UC1827-1 | 制造商:TI 制造商全稱:Texas Instruments 功能描述:Buck Current/Voltage Fed Push-Pull PWM Controllers |
| UC1827-2 | 制造商:TI 制造商全稱:Texas Instruments 功能描述:Buck Current/Voltage Fed Push-Pull PWM Controllers |
| UC1827J-1 | 制造商:TI 制造商全稱:Texas Instruments 功能描述:Buck Current/Voltage Fed Push-Pull PWM Controllers |
| UC1827J-2 | 制造商:TI 制造商全稱:Texas Instruments 功能描述:Buck Current/Voltage Fed Push-Pull PWM Controllers |
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