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參數(shù)資料
| 型號(hào)： | TK75002 |
| 廠商： | TOKO Inc. |
| 英文描述： | ERROR SIGNAL ISOLATOR |
| 中文描述： | 誤差信號(hào)隔離器 |
| 文件頁數(shù)： | 7/10頁 |
| 文件大小： | 77K |
| 代理商： | TK75002 |
January 1999 TOKO, Inc.
Page 7
TK75002
FIGURE 4: ELIMINATING THE Feed-forward OF THE
SUPPLY VOLTAGE IN THE TK75002
ISOLATION WITH PULSE TRANSFORMER
Figure 5 shows an application where the error signal is
isolated with a pulse transformer. The signal is recovered
at the primary side with a peak detector. The circuit is self-
oscillating. The frequency of operation is:
f = V
F
/ [[(I
DRV(PK)
x L
M
) / kV
COMP
+ t
OFF(D)
] x (kV
COMP
+ V
F
)]
(5)
where the various quantities are:
V
F
I
DRV(PK)
peak drive current threshold
L
M
magnetizing inductance of the pulse transformer
k
gain of level shifter stage
t
OFF,D
turnoff delay from peak detection to DRV pin
V
COMP
error signal (voltage at the COMP pin)
forward voltage drop of the internal clamp diode
A 20
μ
H magnetizing inductance, with the typical parameter
values of the TK75002 and an error signal of 1.4 V yields
about 500 kHz oscillation frequency. Such an inductance
can be obtained with three to five turns on a small ferrite
toroid core of 5 to 10 mm external diameter.
APPLICATION INFORMATION (CONT.)
FIGURE 5: ISOLATING THE ERROR SIGNAL WITH A
PULSE TRANSFORMER
ISOLATION WITH OPTO-COUPLER
Figure 6 shows how the TK75002 can be used together
with an opto-coupler. The oscillation is automatically
disabled because the peak current will never reach the
nominal 50 mA peak drive current threshold. A resistor
must be connected in series with the photodiode of the
opto-coupler to limit the maximum current. The main
advantage of the TK75002 over the TL431 is the left-half-
plane zero is avoided. Another advantage is that the error
amplifier in the TK75002 has higher bandwidth than the
TL431.
FIGURE 6: ISOLATING THE ERROR SIGNAL WITH
AN OPTO-COUPLER
V2
Vref
+
-
+
-
V 1
+
+
+
-
2.5 V
R B
+
-
ZFB
ZIN
VCOMP
GND
VCC
DRV
n2
n1
+
OUTPUT OF ISOLATED
TO PRIMARY SIDE
COMP
INV
LM
GND
VCC
COMP
INV
DRV
+
OUTPUT OF ISOLATED
相關(guān)PDF資料 |
PDF描述 |
|---|---|
| TK75002D | ERROR SIGNAL ISOLATOR |
| TK75002DIMG | ERROR SIGNAL ISOLATOR |
| TK75003 | PWM CONTROLLER |
| TK75003D | PWM CONTROLLER |
| TK75003DIMG | PWM CONTROLLER |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| TK75002D | 制造商:TOKO 制造商全稱:TOKO, Inc 功能描述:ERROR SIGNAL ISOLATOR |
| TK75002DIMG | 制造商:TOKO 制造商全稱:TOKO, Inc 功能描述:ERROR SIGNAL ISOLATOR |
| TK75002DIMG/75002 | 制造商:TOKO 制造商全稱:TOKO, Inc 功能描述:ERROR SIGNAL ISOLATOR |
| TK75003 | 制造商:TOKO 制造商全稱:TOKO, Inc 功能描述:PWM CONTROLLER |
| TK75003D | 制造商:TOKO 制造商全稱:TOKO, Inc 功能描述:PWM CONTROLLER |
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