DESCRIPTION KEY FEATURES
■■
■■
■LOW START-UP CURRENT. (0.5mA max.)
■■
■■
■TRIMMED OSCILLATOR DISCHARGE
CURRENT. (See Product Highlight)
pOPTIMIZED FOR OFF-LINE AND DC-TO-DC
CONVERTERS.
pAUTOMATIC FEED FORWARD
COMPENSATION.
pPULSE-BY-PULSE CURRENT LIMITING.
pENHANCED LOAD RESPONSE
CHARACTERISTICS.
pUNDER-VOLTAGE LOCKOUT WITH
HYSTERESIS.
pDOUBLE PULSE SUPPRESSION.
pHIGH-CURRENT TOTEM POLE OUTPUT.
pINTERNALLY TRIMMED BANDGAP
REFERENCE.
p500KHz OPERATION.
pLOW RO ERROR AMPLIFIER.
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
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.
APPLICATIONS
■■
■■
■ECONOMICAL OFF-LINE FLYBACK OR
FORWARD CONVERTERS.
■DC-DC BUCK OR BOOST CONVERTERS.
■LOW COST DC MOTOR CONTROL.
AVAILABLE OPTIONS
Part # Start-Up Hysteresis Max. Duty
Voltage Cycle
PACKAGE ORDER INFORMATION
T
A
(°C)
Plastic DIP
8-pin
0 to 70 UC384xAM UC384xADM UC384xAD —
-40 to 85 UC284xAM UC284xADM UC284xAD UC284xAY
-55 to 125 — — — UC184xAY
M
Plastic SOIC
8-pin
DM
Plastic SOIC
14-pin
D
Ceramic DIP
8-pin
Y
Note: All surface-mount packages are available in Tape & Reel. Append the letter "T" to part number. (i.e. UC3842ADMT)
UCx842A 16V 6V <100%
UCx843A 8.4V 0.8V <100%
UCx844A 16V 6V <50%
UCx845A 8.4V 0.8V <50%
PRODUCT HIGHLIGHT
COMPARISON OF UC384XA VS. SG384X DISCHARGE CURRENT
UC384xA
7.5 8.3 9.3
Mean
SG384x
Min. Limit
7.8
−3σ 8.8
+3σ
SG384x
Max. Limit
Discharge Current Distribution - mA
TA=25°C
CURRENT MODE PWM CONTROLLER
PRODUCTION DATA SHEET
THE INFINITE POWER OF INNOVATION
Copyright © 1995
Rev. 1.2 12/95
FOR FURTHER INFORMATION CALL (714) 898-8121
11861 WESTERN AVENUE, GARDEN GROVE, CA. 92841
UC184xA/284xA/384xA
LIN DOC #:
1840
1