UCC1858 Unitrode Semiconductor, UCC1858 Datasheet
UCC1858
Related parts for UCC1858
UCC1858 Summary of contents
Page 1
... The peak detector eliminates an external 2-pole low pass filter for RMS detection. This simplifies the converter design as well as providing an approximate 6X improvement in input line transient response. The current signal is BLOCK DIAGRAM 7/97 UCC1858 UCC2858 UCC3858 PRELIMINARY continued UDG-96191-1 ...
Page 2
... RMS detection and signal conditioning circuit. Chip shutdown can be attained by bringing the FBL pin below 0.5V. ELECTRICAL CHARACTERISTICS: UCC3858, –40°C to +85°C for the UCC2858, and –55°C to +150°C for the UCC1858, VDD = 12V 24k 330pF, R IAC = 100 ...
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... ELECTRICAL CHARACTERISTICS (cont.): UCC3858, –40°C to +85°C for the UCC2858, and –55°C to +150°C for the UCC1858, VDD = 12V 24k 330pF, R IAC = 100 PARAMETER Voltage Reference (cont.) Load Regulation Line Regulation Short Circuit Current Oscillator Initial Accuracy ...
Page 4
... RT pin. In the absence of a SYNC pulse, CT dis- charges all the way to the ramp low threshold (1V) and that sets the free running frequency of the oscillator as given by equation 1. In applications where synchroniza- tion is used, the RT, CT values should be chosen so that 4 UCC1858 UCC2858 UCC3858 =3/R ) set by the resistor T ...
Page 5
... Pins 4, 9 and 14 need good bypassing to GND for noise immunity. Capacitors C2, C3 and C23 should each consist of a combination of ceramic (0.47 F) and tantalum (4.7 F) capacitors for best results can be fabricated with an Allied Signal Amorphous Core MP4510PFC, using a 100 turn (AWG 18) primary and 5 turn secondary. Figure 1. UCC3858 Typical Application Circuit 5 UCC1858 UCC2858 UCC3858 UDG-97120 ...
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... VAO voltage) falls. As shown in Fig- ure 2, the difference between VAO and FBL regulates current I which subtracts the current available for Csub charging CT. The effective charge current into the capaci- UDG-97123 tor is given by (I CHnom 6 UCC1858 UCC2858 UCC3858 UDG-97121 UDG-97125 Standalone Operation 3 1 3.5 R ...
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... UDG-97130 tated by the UCC3858. The output capacitance value can be significantly reduced if its choice is dictated by ripple 7 UCC1858 UCC2858 UCC3858 UDG-97131 Inverted Switch Sync Leading-Edge Boost PWM ...
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... In such instances, the feedforward effect does not take place and the controller functionality is lost. For UCC3858, the I UDG-97124 zero crossing detection to take place recommended that the capacitor value be kept low enough for the light 8 UCC1858 UCC2858 UCC3858 signal is generated every RMS I ACpk ...
Page 9
... The gain of the amplifier, given should be chosen to achieve desired attenu- ( ation of the output second harmonic ripple (as described in previous Unitrode Application Notes - U-134, U-159) while providing the best transient response. 9 UCC1858 UCC2858 UCC3858 R can- MULT MULT and the voltage at SENSE R 0.5 ...
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... APPLICATION INFORMATION (cont.) Figure 6. Use of the UCC3858 in a Two Stage Converter to Optimize Performance UNITRODE CORPORATION 7 CONTINENTAL BLVD. MERRIMACK, NH 03054 TEL. (603) 424-2410 FAX (603) 424-3460 10 UCC1858 UCC2858 UCC3858 UDG-96192-1 ...