UC3840 ,PROGRAMMABLE, OFF-LIINE, PWM CONTROLLERfeatures of these devices in-
clude a 1% accurate reference, provision for slow,
turn-on and duty ..
UC3840J ,32V; 1000mW; programmable off-line PWM controllerBLOCK DIAGRAM
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UC3840N ,32V; 1000mW; programmable off-line PWM controllertt
I ALL CONTROL, DRIVING, MONITORING, AND
PROTECTION FUNCTIONS INCLUDED
I LOW-CURRENT, OFF- ..
UC3841DW , Programmable, Off-Line, PWM Controller
UC3841DW , Programmable, Off-Line, PWM Controller
UC3841DW , Programmable, Off-Line, PWM Controller
UML2N , Low-frequency transistor (isolated transistor and diode)
UML2N , Low-frequency transistor (isolated transistor and diode)
UML4 N , General purpose transistor (isolated transistor and diode)
UML6 N , General purpose transistors (Isolated transistor and diode)
UML6N , General purpose transistors (Isolated transistor and diode)
UMN10 N , Switching diode
UC2840N-UC3840-UC3840J-UC3840N
PROGRAMMABLE, OFF-LIINE, PWM CONTROLLER
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n ALL CONTROL, DRIVING, MONITORING, AND
PROTECTION FUNCTIONS INCLUDED
u LOW-CURRENT, OFF-LINE START CIRCUIT
n FEED-FORWARD LINE REGULATION OVER 4
TO 1 INPUT RANGE
n PWM LATCH FOR SINGLE PULSE PER PE-
n PULSE-BY-PULSE CURRENT LIMITING PLUS
SHUTDOWN FOR OVER-CURRENT FAULT
a NO START-UP OR SHUTDOWN TRANSIENTS
n SLOW TURN-ON AND MAXIMUM DUTY-CY-
CLE CLAMP
n SHUTDOWN UPON OVER-OR UNDERVOL-
TAGE SENSING
n LATCH OFF OR CONTINUOUS RETRY AFTER
:1 REMOTE, PULSE-COMMANDABLE START/
n PWM OUTPUT SWITCH USABLE TO 1A PEAK
CURRENT
I: 1% REFERENCE ACCURACY
n 500 kHz OPERATION
DESCRIPTION
Although containing most of the features required
by all types of switching power supply controllers,
the UC184O family has been optimized for highly-
efficient boot-strapped primaryside operation in for-
ward or flyback power converters. Two important
features for this mode are a starting circuit which re-
quires little current from the primary input voltage
and feed-forward control for constant Volt-second
operation over a wide input voltage range.
In addition to startup and normal regulating PWM
functions, these devices otter built-in protection from
over-voltage, under-voltage, and over-current fault
conditions. This monitoring circuitry contains the ad-
ded features that any fault will initiate a complete
shutdown with provisions for either latch off or auto-
matic restart. In the latch-off mode, the controller
may be started and stopped with external pulsed or
steady-state commands.
September 1988
H uditiiid
UC2840
UC3840
PROGRAMMABLE, OFF-LINE, PWM CONTROLLER
DIP-18
(Plastic and Ceramic)
Other performance features of these devices in-
clude a 1% accurate reference, provision for slow,
turn-on and duty-cycle limiting, and highspeed
pulse-by-pulse current limiting in addition to current
fault shutdown.
The UC1840's PWM output stage includes a latch
to insure only a single pulse per period and is des-
igned to optimize the turn off of an external switching
device by conducting during the "OFF" time with a
capability for both high peak current and low satu-
ration voltage. These devices are available in an 18-
pin dual-in-line plastic or ceramic package.
The UC184O is characterized for operation over the
full military temperature range of --5erC) to H250.
The UC2840 and UC3840 are designed for opera-
tion from -25 C to +85 C and 00 to +700, respec-
tively.
UC1840-UC2840-UC3840
PIN CONNECTION AND ORDER CODES
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STOP (e. ‘5] “" SUPPLY Type Plastic Ceramic
{ESET C, 1&1 OHWE n was UC1840 - UC1840J
UC2840 UC2840N UC2840J
$333315” (i, H] ammo UC3840 UC3840N U03840J
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ABSOLUTE MAXIMUM RATINGS
Symbol Parameter Test Conditions Unit
V, Supply Voltage + V, (pin 15)
Voltage Driven 32 V
Current Driven 100 mA Maximum Self Limiting
V0 PWM Output Volage (pin 12) 40 V
l, PWM Output Current, Steady-state (pin 12) 400 mA
E0p PWM Output Peak Energy Discharge 20 pJ
Driver Bias Current (pin 14) -200 mA
I. REF; Reference Output Current (pin 16) - 50 mA
Slow Start Sink Current (pin 8) 20 mA
V) Sense Current (pin 11) 10 mA
Current Limit Inputs (pin 6, 7) - 0.5 to + 55 V
Comparator Inputs (pins 2, 3, 4, 5. 17, 18) - 0.3 to + 32 V
Ptot Power Dissipation at Tamb = 70 'C 1000 mW
T, Junction Temperature Range - 55 to + 150 "C
Top Operating Ambient Temperature Range : UC1840 - 55 to + 125 (
UC2840 - 25 to + 85 (
UC3840 0 to + 70 'C
Tstg Storage Temperature - 65 to + 150 'G
THERMAL DATA
Ru, )Vamb Thermal Resistance Junction-ambient Max 80 °C/W
F SGS-THOMSON
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