The UC1842/3/4/5 family of control devices provides the necessary features to implement off-line or dc-to-dc fixed frequency current mode control schemes with a minimal external parts count

UC2845

Manufacturer Part NumberUC2845
DescriptionThe UC1842/3/4/5 family of control devices provides the necessary features to implement off-line or dc-to-dc fixed frequency current mode control schemes with a minimal external parts count
ManufacturerTexas Instruments
UC2845 datasheet
 


Specifications of UC2845

TopologyBoost, Flyback, ForwardControl MethodCurrent
Duty Cycle(max)(%)50Frequency(max)(khz)450
Uvlo Thresholds On/off(v)8.4/7.6Pin/package14SOIC, 8PDIP, 8SOIC
Vin(min)(v)7.6Vin(max)(v)30
Regulated Outputs(#)1Operating Temperature Range(c)-40 to 85
1
Page 1
2
Page 2
3
Page 3
4
Page 4
5
Page 5
6
Page 6
7
Page 7
8
Page 8
9
Page 9
10
Page 10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
Page 8/27

Download datasheet (763Kb)Embed
PrevNext
UC1842/3/4/5
UC2842/3/4/5
UC3842/3/4/5
SLUS223C – APRIL 1997 – REVISED JUNE 2007
OFFLINE FLYBACK REGULATOR
R1
5
1 W
VARO
117 VAC
VM 68
C1
250 F
250 V
56 k
R4
R3
4.7 k
20 k
7
2
R5 150 k
1
C14
UC3844
100 pF
8
R6
10 k
4
C5
5
0.01 F
C6
0.0022 F
Power Supply Specifications
1. Input Voltages
a. 5VAC to 130VA (50 Hz/60 Hz)
2. Line Isolation: 3750 V
3. Switchng Frequency: 40 kHz
4. Efficiency at Full Load 70%
5. Output Voltage:
a. +5 V, 5%; 1A to 4A load
Ripple voltage: 50 mV P-P Max
b. +12 V, 3%; 0.1A to 0.3A load
Ripple voltage: 100 mV P-P Max
c. –12 V, 3%; 0.1A to 0.3A load
Ripple voltage: 100 mV P-P Max
SLOPE COMPENSATION
A fraction of the oscillator ramp can be resistively summed with the current sense signal to provide slope
compensation for converters requiring duty cycles over 50%.
V
REF
R
/ C
T
UC1842/3
I
SENSE
8
R12
C9
4.7 k
3300 pF
2 W
600 V
R2
D4
2 W
1N3613
D2
D3
1N3612
1N3612
R9
C4
C2
C3
68
47 F
100 F
22 F
3 W
25 V
25 V
NC
R7
22
6
R8
3
1 k
USD1120
R13
C7
20 k
470 pF
8
0.1 mF
R
T
4
T
C
T
R1
R2
3
C
Submit Documentation Feedback
www.ti.com
T1
D6
L1
U9D946
+6 V
C11
C10
N5
4700 F
4700 F
10 V
10 V
N
P
COM
D7
UF81002
+12 V
C12
2200 F
N12
16 V
12 V COM
N12
C13
2200 F
16 V
−12 V
D8
UES1002
Q1
C8
UFN833
680 pF
600 V
R10
R11
D8
0.55
2.7 k
1N3613
1 W
2 W
I
SENSE
R
SENSE