IR3094PBF 데이터 시트보기 (PDF) - International Rectifier
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IR3094PBF Datasheet PDF : 29 Pages
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IR3094PBF
APPLICATIONS INFORMATION
OVP
ENABLE
VOUT+
C5VREF
RFB
RROSC
RREF
CREF
ROCSET
RDRP
RCOMP CCOMP
CSC3
CSC2
CSS
RSC3
VIN
RSC2
CVIN
GND
NC
NC
ROSC
VOSNS-
OCSET
VREF
VDRP
FB
EAOUT
SS/DEL
SCOMP2
SCOMP3
IR3094
48LD MLPQ
Cosns-
RSET
VIN
CVCC
PGOOD
GATEH1
PGND1
GATEL1
VCCL1_2
5VUVL
GATEL2
PGND2
GATEH2
VCCH2
VCCH3
GATEH3
PGND3
CBIAS
CBST1
VIN
RCS1
CCS1
1
2
L1
VIN
CBST2
L2
1
2
RCS2
CCS2
VIN
CBST3
L3
1
2
RCS3
CCS3
VOUT SENSE+
VOUT+
COUT
GND
VOUT SENSE-
Figure 6 – System Diagram
Oscillator Resistor RROSC
The oscillator frequency is programmable from 100kHz to 540kHz with an external resistor RROSC as shown in
Figure 6. The Oscillator generates an internal 50% duty cycle sawtooth signal (Figure 3.) that is used to generate
120° out-of-phase timing pulses to set Phase 1,2 and 3 RS flip-flops. Once the switching frequency is chosen,
RROSC can be determined from the curve in the Typical Operating Characteristics Section.
Soft Start, Over-Current Fault Delay, and Hiccup Mode
The IR3094 has a programmable soft-start function to limit the surge current during converter power-up. A capacitor
connected between the SS/DEL and LGND pins controls soft start timing as well as over-current protection delay
and hiccup mode timing.
Figure 8 depicts the various operating modes of the SS/DEL function. Under a no fault condition, the SS/DEL
capacitor will charge. The SS/DEL charge soft-start duration is controlled by a 60uA charge current which charges
CSS up to 4.0V. The Error Amplifier output is clamped low until SS/DEL reaches 1.1V. The Error Amplifier will then
regulate the converter’s output voltage to match the SS/DEL voltage less the 1.1V offset until it reaches the level
determined by the VREF voltage. The PWRGD signal is asserted once the SS/DEL voltage exceeds 3.75V.
Four different faults will immediately cause SS/DEL to begin discharging and set the Fault Latch once SS/DEL is
below 3.75V;
Page 15 of 29
09/26/05
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