LIN DOC #: 1840
UC184xA/284xA/384xA
C U R R E N T M O D E P W M C O N T R O L L E R
P R O D U C T I O N D A T A S H E E T
T H E I N F I N I T E P O W E R O F I N N O V A T I O N
DESCRIPTION
KEY FEATURES
■ LOW START-UP CURRENT. (0.5mA max.)
■ TRIMMED OSCILLATOR DISCHARGE
The UC184xA family of control ICs
provides all the necessary features to
implement off-line fixed-frequency,
current-mode switching power supplies
with a minimum of external compo-
nents. The current mode architecture
demonstrates improved load regulation,
pulse-by-pulse current limiting and
inherent protection of the power supply
output switch. The IC includes: A
bandgap reference trimmed to ±1%
accuracy, an error amplifier, a current
sense comparator with internal clamp to
1V, a high current totem pole output
stage for fast switching of power
MOSFET's, and an externally program-
mable oscillator to set frequency and
CURRENT. (See Product Highlight)
maximum duty cycle. The under-
voltage lock-out is designed to operate
with 250µA typ. start-up current,
allowing an efficient bootstrap supply
voltage design. Available options for
this family of products, such as start-up
voltage hysteresis and duty cycle, are
summarized below in the Available
Options section. The UC184xA family
of control ICs is also available in 14-pin
SOIC package which makes the Power
Output Stage Collector and Ground pins
available.
p OPTIMIZED FOR OFF-LINE AND DC-TO-DC
CONVERTERS.
p AUTOMATIC FEED FORWARD
COMPENSATION.
p PULSE-BY-PULSE CURRENT LIMITING.
p ENHANCED LOAD RESPONSE
CHARACTERISTICS.
p UNDER-VOLTAGE LOCKOUT WITH
HYSTERESIS.
p DOUBLE PULSE SUPPRESSION.
p HIGH-CURRENT TOTEM POLE OUTPUT.
p INTERNALLY TRIMMED BANDGAP
REFERENCE.
p 500KHz OPERATION.
PRODUCT HIGHLIGHT
p LOW RO ERROR AMPLIFIER.
COMPARISON OF UC384XA VS. SG384X DISCHARGE CURRENT
APPLICATIONS
UC384xA
■ ECONOMICAL OFF-LINE FLYBACK OR
SG384x
SG384x
Min. Limit
Max. Limit
FORWARD CONVERTERS.
TA=25°C
■ DC-DC BUCK OR BOOST CONVERTERS.
■ LOW COST DC MOTOR CONTROL.
A
V
A
I
L
A
B
L
E
O P
T I O N S
Part #
Start-Up Hysteresis Max. Duty
Voltage
16V
Cycle
<100%
<100%
<50%
<50%
UCx842A
6V
0.8V
6V
UCx843A 8.4V
UCx844A 16V
UCx845A 8.4V
7.5
7.8
−3σ
8.3
Mean
8.8
+3σ
9.3
0.8V
Discharge Current Distribution - mA
PACKAGE ORDER INFORMATION
Plastic DIP
8-pin
Plastic SOIC
8-pin
Plastic SOIC
14-pin
Ceramic DIP
8-pin
TA (°C)
M
DM
D
Y
0 to 70
-40 to 85
-55 to 125
UC384xAM
UC284xAM
—
UC384xADM
UC284xADM
—
UC384xAD
UC284xAD
—
—
UC284xAY
UC184xAY
Note: All surface-mount packages are available in Tape & Reel. Append the letter "T" to part number. (i.e. UC3842ADMT)
F O R F U R T H E R I N F O R M AT I O N C A L L ( 7 1 4 ) 8 9 8 - 8 1 2 1
Copyright © 1995
Rev. 1.2 12/95
1
11861 WESTERN AVENUE, GARDEN GROVE, CA. 92841