UC3845BD1 Просмотр технического описания (PDF) - Motorola => Freescale
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UC3845BD1 Datasheet PDF : 16 Pages
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UC3844B, 45B UC2844B, 45B
Figure 30. Step–Up Charge Pump Converter
Vin = 15V
Output Load Regulation
(Open Loop Configuration)
1.0nF
8(14)
10k
4(7)
2(3)
1(1)
UC3845B
7(12)
34V
Reference
Regulator
2.5V R
R
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)
+
47
7(11)
1N5819
IO (mA)
0
2
9
18
36
15 10
6(10)
1N5819
+
Connect to
5(8)
Pin 2 for
closed loop
operation.
3(5)
+
47
R2
ǒ Ǔ) VO = 2.5
R2
R1
1
R1
VO (V)
29.9
28.8
28.3
27.4
24.4
VO ≈ 2 (Vin)
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. Voltage–Inverting Charge Pump Converter
UC3845B
1.0nF
8(14)
10k
4(7)
2(3)
1(1)
Reference
Regulator
2.5V
R
Internal
VCC
UVLO
+
–
R
Bias
3.6V
+
–
Vref
UVLO
Osc
+
T
0.5mA 2R
Error
Amplifier
R 1.0V
S
Q
R PWM
Latch
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.
OUTLINE DIMENSIONS
14
MOTOROLA ANALOG IC DEVICE DATA
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