UC3844BDG(2008) データシートの表示（PDF） - ON Semiconductor
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UC3844BDG Datasheet PDF : 19 Pages
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UC3844B, UC3845B, UC2844B, UC2845B
1.0nF
8(14)
10k
4(7)
2(3)
1(1)
UC3845B
7(12)
34V
Reference
2.5V R
R
Regulator
Internal
Bias
3.6V
+
-
Vref
UVLO
VCC
UVLO
+
-
Osc
+
T
0.5mA 2R
Error
Amplifier
R 1.0V
S
Q
R PWM
Latch
Current Sense
Comparator
5(9)
Vin = 15V
+
47
7(11)
1N5819
Output Load Regulation
(Open Loop Configuration)
IO (mA)
VO (V)
0
29.9
2
28.8
9
28.3
18
27.4
36
24.4
15 10
6(10)
1N5819
+
Connect to
5(8)
Pin 2 for
VO ≈ 2 (Vin)
+
47
R2
closed loop
operation.
3(5)
R1
ǒ Ǔ VO = 2.5
R2
R1
)
1
The capacitor's equivalent series resistance must limit the Drive Output current to 1.0 A. An additional series resistor
may be required when using tantalum or other low ESR capacitors. The converter's output can provide excellent line
and load regulation by connecting the R2/R1 resistor divider as shown.
Figure 31. Step−Up Charge Pump Converter
UC3845B
1.0nF
8(14)
10k
4(7)
2(3)
2.5V
R
Internal
R
Bias
3.6V
Osc
+
0.5mA 2R
Error
R
Amplifier
Reference
Regulator
+
-
Vref
UVLO
VCC
UVLO
+
-
T
S
Q
R PWM
1.0V
Latch
1(1)
Current Sense
Comparator
5(9)
7(12)
34V
Vin = 15V
Output Load Regulation
+
47
7(11)
IO (mA)
0
2
9
18
32
VO (V)
−14.4
−13.2
−12.5
−11.7
−10.6
15 10
6(10)
1N5819
VO ≈ -Vin
5(8)
1N5819
+ 47
3(5)
The capacitor's equivalent series resistance must limit the Drive Output current to 1.0 A.
An additional series resistor may be required when using tantalum or other low ESR capacitors.
Figure 32. Voltage−Inverting Charge Pump Converter
http://onsemi.com
14
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