UC3844, UC3845, UC2844, UC2845
MAXIMUM RATINGS
Rating
Total Power Supply and Zener Current
Output Current, Source or Sink (Note 1)
Output Energy (Capacitive Load per Cycle)
Current Sense and Voltage Feedback Inputs
Error Amp Output Sink Current
Power Dissipation and Thermal Characteristics
D Suffix, Plastic Package, Case 751A
Maximum Power Dissipation @ T
A
= 25°C
Thermal Resistance Junction−to−Air
N Suffix, Plastic Package, Case 626
Maximum Power Dissipation @ T
A
= 25°C
Thermal Resistance Junction−to−Air
Operating Junction Temperature
Operating Ambient Temperature
UC3844, UC3845
UC2844, UC2845
Storage Temperature Range
Symbol
(I
CC
+ I
Z
)
I
O
W
V
in
I
O
Value
30
1.0
5.0
−
0.3 to + 5.5
10
Unit
mA
A
mJ
V
mA
P
D
R
qJA
P
D
R
qJA
T
J
T
A
862
145
1.25
100
+ 150
0 to + 70
−
25 to + 85
−
65 to + 150
mW
°C/W
W
°C/W
°C
°C
T
stg
°C
Stresses exceeding Maximum Ratings may damage the device. Maximum Ratings are stress ratings only. Functional operation above the
Recommended Operating Conditions is not implied. Extended exposure to stresses above the Recommended Operating Conditions may affect
device reliability.
1. Maximum Package power dissipation limits must be observed.
ELECTRICAL CHARACTERISTICS
(V
CC
= 15 V, (Note 2), R
T
= 10 k, C
T
= 3.3 nF, T
A
= T
low
to T
high
(Note 3), unless otherwise noted.)
UC284X
Characteristics
REFERENCE SECTION
Reference Output Voltage (I
O
= 1.0 mA, T
J
= 25°C)
Line Regulation (V
CC
= 12 V to 25 V)
Load Regulation (I
O
= 1.0 mA to 20 mA)
Temperature Stability
Total Output Variation over Line, Load, Temperature
Output Noise Voltage (f = 10 Hz to kHz, T
J
= 25°C)
Long Term Stability (T
A
= 125°C for 1000 Hours)
Output Short Circuit Current
OSCILLATOR SECTION
Frequency
T
J
= 25°C
T
A
= T
low
to T
high
Frequency Change with Voltage (V
CC
= 12 V to 25 V)
Frequency Change with Temperature
T
A
= T
low
to T
high
Oscillator Voltage Swing (Peak−to−Peak)
Discharge Current (V
osc
= 2.0 V, T
J
= 25°C)
ERROR AMPLIFIER SECTION
Voltage Feedback Input (V
O
= 2.5 V)
Input Bias Current (V
FB
= 2.7 V)
Open Loop Voltage Gain (V
O
= 2.0 V to 4.0 V)
V
FB
I
IB
A
VOL
2.45
−
65
2.5
−0.1
90
2.55
−1.0
−
2.42
−
65
2.5
−0.1
90
2.58
−2.0
−
V
mA
dB
f
osc
47
46
−
−
−
−
52
−
0.2
5.0
1.6
10.8
57
60
1.0
−
−
−
47
46
−
−
−
−
52
−
0.2
5.0
1.6
10.8
57
60
1.0
−
−
−
kHz
V
ref
Reg
line
Reg
load
T
S
V
ref
V
n
S
I
SC
4.95
−
−
−
4.9
−
−
−
30
5.0
2.0
3.0
0.2
−
50
5.0
−
85
5.05
20
25
−
5.1
−
−
−
180
4.9
−
−
−
4.82
−
−
−
30
5.0
2.0
3.0
0.2
−
50
5.0
−
85
5.1
20
25
−
5.18
−
−
−
180
V
mV
mV
mV/°C
V
mV
mV
mA
Symbol
Min
Typ
Max
Min
UC384X
Typ
Max
Unit
Df
osc/
D
V
Df
osc/
D
T
V
osc
I
dischg
%
%
V
mA
2. Adjust V
CC
above the Startup threshold before setting to 15 V.
3. Low duty cycle pulse techniques are used during test to maintain junction temperature as close to ambient as possible.
T
high
= +70°C for UC3844, UC3845
T
low
= 0°C for UC3844, UC3845
−25°C
for UC2844, UC2845
+85°C for UC2844, UC2845
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