Service Manual
12
normal operating.
The typical current mode PWM controller feedbacks both current signal and
voltage signal to close the control loop and achieve ragulation.U850 detects the
Q850 current from Isense pin which max voltage is set as 0.85V, then the Q850
current can be calculated as:I peak=0.85V/R869,When the sense voltage across the
sense resistor R869, reaches the threshold voltage over 0.85V, the output GATE
drive will be turned off. R849 and C846 is used to avoid the Isen pin damaged by
the negative turn-on spike.
The voltage feedback signal is provided from the TL431(I851) through the I850
to the COMP pin.When the voltage on COMP pin is lower than 1.2V,the IC will
turn off.
When Q850 is turned off, the main current flow will be consumed through
D851, C875, R880, this will prevent Q850 from being damaged under large
current impulse and voltage spike.
RT pin is to program the switching frequency ,by connecting R846 to
ground to set the switching frequency,f =(65.0/R846)*100(KHz).
2.2.4) DC 13V and DC 5V Output Circuit and Feedback circuit:(fig.7)
I850
LTV817
3
1
4
2
+13V
C860
3300p/250V
L851
CHK-053
R861
3K6 1%
C871
0.1/50V
+
C863
470u/25V
D854
NC/SF5-20
+
C867
470u/25V
C862
1000p/1000V
R860
3K3 1%
L852
CHK-053
I851
TL431
3
1
2
+
C869
470u/25V
R866
10R 2W/JUMP
D856
SR5-10
F851
5A/125V
.
.
.
T851
NC
5
8
6
7
3
1
12
11
9
10
D855
SF5-20
C866
1000p/1000V
C876
0.1/50V
R859
10K 1%
+
C899
OPEN
D857
SR5-10
.
.
.
T850
SPW-119
5
8
6
7
3
1
12
11
9
10
R867
270
C861 OPEN
R862
10R 2W/JUMP
DIM/ON/OFF
+5V
PID
+
C868
470u/25V
CN851
SIP-8P
6
1
2
5
3
4
7
8
+5V
+5V
GND
GND
DIM
ENA
PID
P-saving_on/off
R858
5K1 1%
+
C864
470u/25V
R871
270k
R899 OPEN
C859
0.01/50V
Fig.7
D855 is used to rectify the inducted current. R862 and C862 are used to store
Содержание ST2010 - 20" LCD Monitor
Страница 1: ...Service Manual 0 Service Manual LCD Monitor ST2010 ...
Страница 20: ...Service Manual 19 ...
Страница 21: ...Service Manual 20 8 Key Parts Pin Assignments 8 1 U105 TSUMU58EDJ LF ...
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Страница 27: ...Service Manual 26 Chapter 4 Disassembly Assembly 1 Exploded Diagram ...
Страница 30: ...Service Manual 29 3 ST2010 Assembly Block ...
Страница 32: ...Service Manual 31 ...
Страница 60: ...Service Manual 59 Attachment 2 Schematic 1 Interface board schematic ...
Страница 68: ...Service Manual 67 power board schematic 1 ...
Страница 69: ...Service Manual 68 ...
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Страница 72: ...Service Manual 71 Attachment 3 PCB Layout Power inverter board Top Layer ...
Страница 73: ...Service Manual 72 Bottom Layer ...
Страница 74: ...Service Manual 73 I F board Top Layer Bottom Layer ...
Страница 75: ...Service Manual 74 Keypad ...
Страница 76: ...Service Manual 75 ...