UC3842 NXP Semiconductors, UC3842 Datasheet
UC3842
Available stocks
Related parts for UC3842
UC3842 Summary of contents
Page 1
... Philips Semiconductors Linear Products Current-mode PWM controller DESCRIPTION The UC3842 is available in an 8-Pin mini-DIP the necessary features to implement off-line, fixed-frequency current-mode control schemes with a minimal external parts count. This technique results in improved line regulation, enhanced load response characteristics, and a simpler, easier to design control loop. Topological advantages include inherent pulse-by-pulse current limiting ...
Page 2
... See section in application note on “Power Dissipation Calculation”. 3. This parameter is guaranteed, but not 100% tested in production. August 31, 1994 TEMPERATURE RANGE +70 C RATING 30 -0 -65 to +150 300 1101 Product specification UC3842 ORDER CODE DWG # UC3842N 0404B UC3842D 0405B UNIT Self-Limiting ...
Page 3
... Philips Semiconductors Linear Products Current-mode PWM controller DC AND AC ELECTRICAL CHARACTERISTICS for UC3842; V =15V; R =10kW SYMBOL SYMBOL PARAMETER PARAMETER Reference section V Output voltage OUT Line regulation Load regulation 1 Temp. stability 1 Total output variation 1 V Output noise voltage NOISE 1 Long-term stability Output short-circuit ...
Page 4
... Philips Semiconductors Linear Products Current-mode PWM controller DC AND AC ELECTRICAL CHARACTERISTICS for UC3842 =10k ; SYMBOL SYMBOL PARAMETER PARAMETER Output section V V Output Low-Level Output Low-Level Output High-Level Output High-Level Rise time R t Fall time F Undervoltage lockout section Start threshold Min. operating voltage after turn on ...
Page 5
... OUTPUT CURRENT, SOURCE OR SINK (A) August 31, 1994 ERROR AMP GND 100 –20 0.3 0.5 1.0 1104 Product specification UC3842 CURRENT SENSE COMPARATOR Error Amplifier Open-Loop Frequency Response –45 –90 –135 0 –180 –225 10 100 1k 10k 100k 1M 10M FREQUENCY (Hz) ...
Page 6
... NOTE: Shutdown of the UC3842 can be accomplished by two methods; either raise Pin 3 above 1V or pull Pin 1 below a voltage two diode drops above ground. Either method causes the output of the PWM comparator to be high (refer to Block Diagram). The PWM latch is reset dominant so that the output will remain low until the next clock cycle after the shutdown condition at Pins 1 and/ removed ...
Page 7
... AC This circuit uses a low-cost feedback scheme in which the DC voltage developed from the primary-side control winding is sensed by the UC3842 error amplifier. Load regulation is therefore dependent on the coupling between secondary and control windings, and on transformer leakage inductance. For applications requiring better load regulation, a UC1901 Isolated Feedback Generator can be used to directly sense the output voltage ...
Page 8
... Philips Semiconductors Linear Products Current-mode PWM controller SYNCHRONIZATION AND MAXIMUM DUTY CYCLE CLAMP NOTES: 1. MAX August 31, 1994 RESET DISCH R 3 OUT NE555 2 TRIG 6 THRESH GND 1 TO OTHER UC3842s 1107 Product specification UC3842 UC3842 4 5 GND ...