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T H E I N F I N I T E P O W E R O F I N N O VAT I O N
L I N D O C #: 1840
UC184xA/284xA/384xA
CURRENT MODE PWM CONTROLLER PR O D U C T I O N D ATA S H E E T
DESCRIPTION
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 components. 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 programmable oscillator to set frequency and maximum duty cycle. The undervoltage 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.
PRODUCT HIGHLIGHT
COMPARISON OF UC384XA VS. SG384 X DISCHARGE CURRENT
SG384x
Min. Limit
UC384xA
TA=25°C
SG384x
Max. Limit
KEY FEATURES
s LOW START-UP CURRENT. (0.5mA max.) s TRIMMED OSCILLATOR DISCHARGE
CURRENT. (See Product Highlight) 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. p LOW RO ERROR AMPLIFIER.
A P P L I C AT I O N S
s ECONOMICAL OFF-LINE FLYBACK OR FORWARD CONVERTERS.
s DC-DC BUCK OR BOOST CONVERTERS. s LOW COST DC MOTOR CONTROL.
7.5 7.8 −3σ
8.3 Mean
8.8 9.3 +3σ
Discharge Current Distribution - mA
AVAILABLE OPTIONS
Part # Start-Up Hysteresis Max. Duty
Voltage
Cycle
UCx842A 16V
6V <100%
UCx843A 8.4V 0.8V <100%
UCx844A 16V
6V <50%
UCx845A 8.4V 0.8V <50%
TA (°C)
PACKAGE ORDER INFORMATION
M
Plastic DIP 8-pin
DM
Plastic 8-pin
SOIC
D
Plastic SOIC 14-pin
Y
Ceramic DIP 8-pin
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)
Copyright © 1995 Rev. 1.2 12/95
FOR FURTHER INFORMATION CALL (714) 898-8121 11861 WESTERN AVENUE, GARDEN GROVE, CA. 92841
1
PRODUCT DATABOOK 1996/1997
UC184xA/284xA/384xA
CURRENT MODE PWM CONTROLLER PRODUCTION DATA SHEET
A B S O L U T E M A X I M U M R AT I N G S (Note 1)
Supply Voltage (Low Impedance Source) (VCC) ......................................................... 30V Supply Voltage (ICC < 30mA) .......................................................................... Self Limiting Output Current ............................................................................................................. ±1A Output Energy (Capacitive Load) ................................................................................. 5µJ Analog Inputs (VFB & ISENSE) ........................................................................ -0.3V to +6.3V Error Amp Output Sink Current ............................................................................... 10mA Power Dissipation at TA = 25°C (M Package) .............................................................. 1W Storage Temperature Range .................................................................... -65°C to +150°C Lead Temperature (Soldering, 10 Seconds) ............................................................. 300°C
Note 1. Exceeding these ratings could cause damage to the device. All voltages are with respect to Ground. Currents are positive into, negative out of the specified terminal. Pin numbers refer to DIL packages only.
T H E R MAL DATA
M PACKAGE:
THERMAL RESISTANCE-JUNCTION TO AMBIENT, θJA DM PACKAGE:
95°C/W
THERMAL RESISTANCE-JUNCTION TO AMBIENT, θJA D PACKAGE:
165°C/W
THERMAL RESISTANCE-JUNCTION TO AMBIENT, θJA Y PACKAGE:
120°C/W
THERMAL RESISTANCE-JUNCTION TO AMBIENT, θJA
130°C/W
Junction Temperature Calculation: TJ = TA + (PD x θJA). The θJA numbers are guidelines for the thermal performance of the device/pc-board system. All of the above assume no ambient airflow
PACKAGE PIN OUTS
COMP
VFB ISENSE RT/CT
1 2 3 4
8 VREF 7 VCC 6 OUTPUT
5 GND
M & Y PACKAGE (Top View)
COMP
VFB ISENSE RT/CT
1 8 VREF 2 7 VCC 3 6 OUTPUT
4 5 GND
DM PACKAGE (Top View)
COMP
N.C.
VFB N.C.
ISENSE N.C.
RT/CT
1 14 VREF 2 13 N.C. 3 12 VCC 4 11 VC 5 10 OUTPUT 6 9 GND 7 8 PWR GND
D PACKAGE (Top View)
2 Copyright © 1995 Rev. 1.2 12/95
PRODUCT DATABOOK 1996/1997.