US3033 UNISEM, US3033 Datasheet
US3033
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US3033 Summary of contents
Page 1
... Typical application of US3033 in a flexible mother board designed for Intel P55 ,P54 AMD K5,K6 as well as Cyrix M1 and M2 applications. Notes: P54C,P55C,Pentium II are trade marks of Intel Corp. K5 & K6 are trade marks of AMD corp. Cyrix 6X86L,M1,M2 are trade marks of Cyrix Corp. Power PC is trade mark of IBM Corp. ...
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... US3033 ABSOLUTE MAXIMUM RATINGS ABSOLUTE MAXIMUM RATINGS V ,V Supply Voltages ............................................................. 20V 12 12SW F.B Pin Voltages........................................................ Storage Temperature Range ................................. -65 TO 150 C Operating Junction Temperature ............................... 0 TO 150 C PACKAGE INFORMATION PACKAGE INFORMATION 8 PIN PLASTIC SOIC (S) TOP VIEW Drv1 1 8 V12 V12sw Drv2 2 7 Vfb1 3 6 Vfb2 ...
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... Gnd is required to filter the switching noise of the switching regulator. BLOCK DIAGRAM BLOCK DIAGRAM V12sw Vhyst 2 4 Drv 1 1 Gnd 5 Figure 1 - Simplified block diagram of the US3033 Rev. 1.5 1/14/99 Vfb 1 3 UVLO Vref PWM Control 1.25V 3033blk1-1.0 US3033 pin to set the ...
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... Figure2- Typical application of US3033 in a flexible motherboard with the 4 bit VID output voltage selection. This circuit uses a single jumper that programs the output voltage in 16 steps with 0.1V steps from 2V to 3.5V, designed for Intel P55 ,P54 , AMD K5 & well as Cyrix M1 and M2 processor is dropped in the socket ...
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... Note 1: For the applications where it is desirable to eliminate the heat sink, the IRL3103S for Q2 and MBR1545CT for D2 in TO263 packages with minimum of 1" square copper pad can be used. Rev. 1.5 1/14/99 Part # US3033CS ( 8 pin SOIC) MTP3055 (TO220) IRL3303 (TO220) IRL3103S (TO263) (note 1) 1N4148 ...
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... HS2 Heat Sink 1 4-6 Figure3- This unique application of US3033 allows the de- signer to switch between Linear or Switching mode of operation using a single IC. This circuit has the flexibility used for low current operation in Linear mode for cost reasons and yet be able to operate in the Switching ...
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... Figure4- The circuit in figure 4 is the application of the US3033 in a switching mode only. This circuit can be used to generate a low cost 5V to 3.3V for either Pentium application with AGP socket or in Pentium II applications where it is desirable to generate an accurate on board 3.3V supply. Ref Desig ...
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... R1=Resistor connected from Vout to the Vfb2 pin of US3033 R2=Resistor connected from Vfb2 pin to GND. The US3033 requires the use of an output capacitor as part of the frequency compensation in order to be stable. Typical designs for the microprocessor applications use standard electrolytic capacitors with typical ESR in the range 100 m and an output capacitance of 500 to 1000uF ...
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... Where: Rb=Bottom resistor of the divider X= ( Vo/2))/Vref - 1 Vref=1.25 V typ. X= (3.38+ (0.044/2))/1. 1.72 Rb=1000/1.72=580 Select Rb=576 , 1% Frequency Calculation The US3033 frequency of operation is calculated using the following formula: Fs= (Vo*(1-D)*ESR) /(L* Vo) (MHz) Where: Vo=Output voltage (V) D=Duty cycle ESR=Output capacitor ESR (V) L=Output inductance (uH) Vo=Output ripple voltage (V) ...