PRODUCT DATABOOK 1996/1997
UC184xA/284xA/384xA
C
URRENT
M
ODE
PWM C
ONTROLLER
P
R O D U C T I O N
D
A T A
S
H E E T
ELECTRICAL CHARACTERISTICS
Parameter
Under-Voltage Lockout Section
Start Threshold
Min. Operation Voltage After Turn-On
x842A/4A
x843A/5A
x842A/4A
x843A/5A
x842A/3A
x844A/5A
(Con't.)
Symbol
Test Conditions
UC184xA/284xA
UC384xA
Units
Min. Typ. Max. Min. Typ. Max.
15
7.8
9
7.0
94
47
16
8.4
10
7.6
96
48
17
9.0
11
8.2
100
50
0
0.5
17
30
14.5
7.8
8.5
7.0
94
47
16
8.4
10
7.6
96
48
17.5
9.0
11.5
8.2
100
50
0
0.5
17
V
V
V
V
%
%
%
mA
mA
V
PWM Section
Maximum Duty Cycle
Minimum Duty Cycle
Total Standby Section
Start-Up Current
Operating Supply Current
Zener Voltage
I
CC
V
Z
0.3
11
35
0.3
11
35
I
CC
= 25mA
30
Notes: 2. These parameters, although guaranteed, are not 100% tested in
production.
3. Parameter measured at trip point of latch with V
VFB
= 0.
4. Gain defined as: A
VOL
=
∆
V
COMP
; 0
≤
V
ISENSE
≤
0.8V.
∆
V
ISENSE
7. "Temperature stability, sometimes referred to as average temperature
coefficient, is described by the equation:
V
REF
(max.) - V
REF
(min.)
Temp Stability =
T
J
(max.) - T
J
(min.)
V
REF
(max.) & V
REF
(min.) are the maximum & minimum reference
voltage measured over the appropriate temperature range. Note that
the extremes in voltage do not necessarily occur at the extremes in
temperature."
5. Adjust V
CC
above the start threshold before setting at 15V.
6. Output frequency equals oscillator frequency for the UC1842A
and UC1843A. Output frequency is one half oscillator frequency
for the UC1844A and UC1845A.
BLOCK DIAGRAM
V
CC
*
34V
UVLO
Hysteresis
6V (1842A/4A)
0.8V (1843A/5A)
GROUND
**
UVLO
16V (1842A/4A)
8.4V (1843A/5A)
2.5V
S/R
5V
Ref
Internal
Bias
V
REF
5.0V
50mA
V
REF
Good Logic
R
T
/C
T
Oscillator
***
Error Amp
V
FB
COMP
CURRENT SENSE
2R
R
1V
S
R
Current Sense
Comparator
PWM
Latch
T
*
V
C
OUTPUT
**
POWER GROUND
* - V
CC
and V
C
are internally connected for 8 pin packages.
** - POWER GROUND and GROUND are internally connected for 8 pin packages.
*** - Toggle flip flop used only in x844A and x845A series.
4
Copyright © 1995
Rev. 1.2 12/95
MICROSEMI [ MICROSEMI CORPORATION ]
