UC3845 Ver la hoja de datos (PDF) - Motorola => Freescale
Número de pieza
componentes Descripción
Fabricante
UC3845 Datasheet PDF : 14 Pages
| |||
UC3844, 45 UC2844, 45
Figure 30. Step–Up Charge Pump Converter
Vin = 15V
UC3845
+
7(12)
47
Output Load Regulation
(open loop configuration)
8(14)
R
2.5V
Internal
Bias
10k
R
4(7)
1.0nF
2(3)
1(1)
Oscillator
+
0.5mA
+
2R
–
Error
R
Amplifier
Reference
+
34V
Regulator
+
VCC – +
UVLO –
3.6V + – Vref
– UVLO
T
–
+
1.0V
S
Q
R PWM
Latch
Current Sense
Comparator
1N5819
7(11)
IO (mA)
0
2
9
18
36
VO (V)
29.9
28.8
28.3
27.4
24.4
6(10) 15 10 1N5819
+
+
Connect to
5(8)
Pin 2 for
R2
closed loop
operation.
VO 2 (Vin)
47
3(5)
VO = 2.5
R2
R2
+1
R1
5(9)
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
UC3845
Vin = 15V
+
7(12)
47
8(14)
R
Internal
2.5V
Bias
Reference
+
34V
Regulator
+
VCC – +
UVLO –
10k
4(7)
1.0nF
2(3)
1(1)
R
Oscillator
+
0.5mA
+
2R
–
Error
R
Amplifier
3.6V + – Vref
– UVLO
T
–
+
1.0V
S
Q
R PWM
Latch
Current Sense
Comparator
5(9)
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.
7(11)
6(10) 15 10
+
1N5819
5(8)
1N5819
+
VO – (Vin)
47
Output Load Regulation
3(5)
IO (mA)
VO (V)
0
–14.4
2
–13.2
9
–12.5
18
–11.7
32
–10.6
MOTOROLA ANALOG IC DEVICE DATA
13
Share Link: 