UC3845DR2 ON Semiconductor, UC3845DR2 Datasheet - Page 13

• Manufacturer Part Number: UC3845DR2
• Description: IC CTRLR CURRENT MODE HP 14SOIC
• Manufacturer: ON Semiconductor
• Type: High Performance Current Mode Controllersr

Specifications of UC3845DR2

• Pwm Type: Current Mode
• Number Of Outputs: 1
• Frequency - Max: 60kHz
• Duty Cycle: 50%
• Voltage - Supply: 8.2 V ~ 25 V
• Buck: No
• Boost: Yes
• Flyback: Yes
• Inverting: Yes
• Doubler: No
• Divider: No
• Cuk: No
• Isolated: Yes
• Operating Temperature: 0°C ~ 70°C
• Package / Case: 14-SOIC (3.9mm Width), 14-SOL
• Frequency-max: 60kHz
• Output Voltage Range: 4.9 V to 5.1 V
• Input Voltage Range: 30 V
• Operating Temperature Range: 0 C to + 70 C
• Mounting Style: SMD/SMT
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Other names: UC3845DR2OSTR

10k
1.0nF
10k
1.0nF
8(14)
4(7)
2(3)
1(1)
8(14)
4(7)
2(3)
1(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.
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.
2.5V
2.5V
Amplifier
+
−
Amplifier
+
−
Error
R
Error
R
R
R
+
Oscillator
+
Oscillator
0.5mA
Internal
0.5mA
Bias
Internal
Bias
2R
2R
Figure 32. Voltage−Inverting Charge Pump Converter
UC3845
R
UC3845
R
Figure 31. Step−Up Charge Pump Converter
5(9)
5(9)
3.6V
1.0V
3.6V
Current Sense
Comparator
1.0V
Current Sense
Comparator
Reference
Regulator
Reference
+
−
Regulator
+
−
−
+
+
−
−
+
+
−
UVLO
V
UVLO
http://onsemi.com
ref
V
ref
S
R
T
S
R
UVLO
T
V
Q
UVLO
CC
V
Q
CC
13
PWM
Latch
PWM
Latch
−
+
−
+
−
+
−
+
7(12)
7(12)
34V
34V
V
in
V
in
= 15V
3(5)
7(11)
6(10)
5(8)
= 15V
3(5)
7(11)
6(10)
5(8)
+
V
15 10
O = 2.5
15 10
1N5819
+
Connect to
Pin 2 for
closed loop
operation.
+
47
+
R2
R2
1N5819
47
1N5819
Output Load Regulation
+ 1
I
O
(mA)
18
32
(open loop configuration)
0
2
9
Output Load Regulation
I
1N5819
O
R2
R1
(mA)
18
36
0
2
9
+
+
V
47
−14.4
−13.2
−12.5
−11.7
−10.6
O
47
(V)
V
V
29.9
28.8
28.3
27.4
24.4
O
O
V
O
(V)
 2 (V
 − (V
in
)
in
)