Datasheet

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ELECTRICALCHARACTERISTICS
TPS54550
SLVS623A–MARCH2006–REVISEDAPRIL2006
T
J
=–40°Cto+125°C,VIN=4.5Vto20V(unlessotherwisenoted)
PARAMETERTESTCONDITIONS MINTYPMAXUNIT
SUPPLYCURRENT
Operatingcurrent,PHpinopen,
10.3mA
Noexternallow-sideMOSFET,RT=Hi-Z
I
Q
Quiescentcurrent
Shutdown,SSENA=0V1.1mA
Startthresholdvoltage4.324.49V
VINStopthresholdvoltage3.693.97V
Hysteresis350mV
UNDERVOLTAGELOCKOUT(UVLOPIN)
Startthresholdvoltage1.201.24V
UVLOStopthresholdvoltage1.021.10V
Hysteresis100mV
BIASVOLTAGE(VBIASPIN)
I
VBIAS
=1mA,VIN≥12V7.57.88.0
VBIASOutputvoltageV
I
VBIAS
=1mA,VIN=4.5V4.44.474.5
REFERENCESYSTEMACCURACY
T
J
=25°C0.8880.8910.894V
Referencevoltage
0.8820.8910.899V
OSCILLATOR(RTPIN)
RTgrounded200250300
InternallysetPWMswitchingfrequencykHz
RTopen400500600
ExternallysetPWMswitchingfrequencyRT=100kΩ(1%resistortoAGND)425500575kHz
FALLINGEDGETRIGGEREDBIDIRECTIONALSYNCSYSTEM(SYNCPIN)
SYNCoutlow-to-highrisetime(10%/90%)
(1)
25pFtoground200500ns
SYNCouthigh-to-lowfalltime(90%/10%)
(1)
25pFtoground510ns
Delayfromrisingedgetorisingedgeof
Fallingedgedelaytime
(1)
180°
PHpins
Minimuminputpulsewidth
(1)
RT=100kΩ100ns
Delay(fallingedgeSYNCtorisingedgePH)
(1)
RT=100kΩ360ns
50kΩresistortoground,
SYNCouthighlevelvoltage2.5V
Nopull-upresistor
SYNCoutlowlevelvoltage0.6V
SYNCinlowlevelthreshold0.8V
SYNCinhighlevelthreshold2.3V
Percentageofprogrammedfrequency–10+10%
SYNCinfrequencyrange
(1)
225770kHz
FEED-FORWARDMODULATOR(INTERNALSIGNAL)
ModulatorgainVIN=12V,T
J
=+25°C8V/V
Modulatorgainvariation–25+25%
MinimumcontrollableONtime
(1)
180ns
Maximumdutyfactor
(1)
VIN=4.5V80%86%
ERRORAMPLIFIER(VSENSEandCOMPPINS)
Erroramplifieropen-loopvoltagegain
(1)
6080dB
Erroramplifierunitygainbandwidth
(1)
1.02.8MHz
Inputbiascurrent,VSENSEpin500nA
COMPOutputvoltageslewrate(symmetric)
(1)
1.5V/μs
(1)Specifiedbydesign,notproductiontested.
4
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