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參數(shù)資料
| 型號： | LTC3880IUJ#PBF |
| 廠商： | LINEAR TECHNOLOGY CORP |
| 元件分類： | 穩(wěn)壓器 |
| 英文描述： | 0.1 A DUAL SWITCHING CONTROLLER, 1000 kHz SWITCHING FREQ-MAX, PQCC40 |
| 封裝： | 6 X 6 MM, LEAD FREE, PLASTIC, WJJD-2, QFN-40 |
| 文件頁數(shù)： | 27/112頁 |
| 文件大?。?/td> | 2182K |
| 代理商： | LTC3880IUJ#PBF |
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LTC3880/LTC3880-1
21
3880fa
Figure 4. Temperature Sense Circuit
TSNS
MMBT3906
LTC3880
10nF
SGND
3880 F04
OPERATION
near the inductor and used to modify the internal current
limit circuit to maintain an essentially constant current
limit with temperature. In this application, the ISENSEn+
pin is connected to the FET side of the capacitor while the
ISENSEn– pin is placed on the load side of the capacitor.
The current sensed from the input is then given by the
expression VDCR/DCR. VDCR is digitized by the LTC3880’s
telemetry ADC with an input range of ±128mV, a noise
floor of 7VRMS, and a peak-peak noise of approximately
46.5V. The LTC3880 computes the inductor current using
the DCR value stored in the IOUT_CAL_GAIN command
and the temperature coefficient stored in command
MFR_IOUT_CAL_GAIN_TC. The resulting current value
is returned by the READ_IOUT command.
LOAD SHARING
Multiple LTC3880’s can be arrayed in order to provide a
balanced load-share solution by bussing the necessary
pins. Figure 3 illustrates the shared connections required
for load sharing.
The frequency must only be programmed on one of the
LTC3880s. The other(s) must be programmed to External
Clock.
EXTERNAL/INTERNAL TEMPERATURE SENSE
Externaltemperaturecanbebestmeasuredusingaremote
diode-connected PNP transistor such as the MMBT3906.
TheemittershouldbeconnectedtotheTSNSnpinwhilethe
base and collector terminals of the PNP transistor should
be returned to the LTC3880’s SGND pin, preferably using a
starconnection.Itispossibletoconnectthecollectorofthe
PNPtothesourceofthebottomMOSFET.Thismayoptimize
boardlayoutallowingthePNPcloserproximitytothepower
FETs.ThebaseofthePNPmuststillbetiedtosignalground.
Forbestnoiseimmunity,theconnectionsshouldberouted
differentially and a 10nF capacitor should be placed in
parallelwiththediodeconnectedPNP.Twodifferentcurrents
are applied to the diode (nominally 2A and 32A) and the
temperatureiscalculatedfromthe
VBEmeasurement.The
external transistor temperature is digitized by the telem-
etry ADC, and the value is returned by the PMBus READ_
TEMPERATURE_1 (Chn) command.
The READ_TEMPERATURE_2 command returns the junc-
tion temperature of the LTC3880 using an on-chip diode.
The slope of the external temperature sensor can be
modified with the temperature slope coefficient stored in
MFR_TEMP_1_GAIN. Typical PNPs require temperature
slopeadjustmentsslightlylessthan 1.TheMMBT3906has
a recommended value in this command of approximately
MFR_TEMP_1_GAIN = 0.991 based on the ideality factor
of 1.01. Simply invert the ideality factor to calculate the
MFR_TEMP_1_GAIN. Different manufacturers and differ-
ent lots may have different ideality factors. Consult with
the manufacturer to set this value.
Theoffsetoftheexternaltemperaturesensecanbeadjusted
by MFR_TEMP_1_OFFSET. A value of 0 in this register sets
the temperature offset to –273.15°C.
If the PNP cannot be placed in direct contact with the
inductor, the slope or offset can be increased to account
for temperature mismatches. If the user is adjusting the
slope,theinterceptpointisatabsolutezero,–273.15°C,so
small adjustments in slope can change the apparent mea-
sured temperature significantly. Another way to artificially
increase the slope of the temperature term is to increase
the MFR_IOUT_CAL_GAIN_TC term. This will modify the
temperature slope with respect to room temperature.
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| LTC3883EUH#PBF | 制造商:Linear Technology 功能描述:IC REG CTRLR BUCK PWM VM 32-QFN 制造商:Linear Technology 功能描述:BUCK CNTRL 24V 1MHZ 0.5/5.5V 32QFN 制造商:Linear Technology 功能描述:BUCK, CNTRL, 24V, 1MHZ, 0.5/5.5V, 32QFN 制造商:Linear Technology 功能描述:PWM CONTROLLER, BUCK, 1MHZ, 24V, QFN-32, Input Voltage:24V, Output Voltage:5.5V, Output Current:30A, Supply Voltage Min:4.5V, Supply Voltage Max:24V, Digital IC Case Style:QFN, No. of Pins:32, Frequency:1MHz, MSL:MSL 1 - Unlimited , RoHS Compliant: Yes 制造商:Linear Technology 功能描述:DP-SWREG/Controller, Digitally Programmable, Multiphase Step-Down DC/DC Controll |
| LTC3883EUH#TRPBF | 制造商:Linear Technology 功能描述:IC REG CTRLR BUCK PWM VM 32-QFN 制造商:Linear Technology 功能描述:DP-SWREG/Controller, Digitally Programmable, Multiphase Step-Down DC/DC Controll |
| LTC3883EUH-1#PBF | 制造商:Linear Technology 功能描述:IC REG CTRLR BUCK PWM VM 32-QFN 制造商:Linear Technology 功能描述:BUCK CNTRL 24V 1MHZ 0.5/5.5V 32QFN 制造商:Linear Technology 功能描述:BUCK, CNTRL, 24V, 1MHZ, 0.5/5.5V, 32QFN 制造商:Linear Technology 功能描述:PWM CONTROLLER, BUCK, 1MHZ, 24V, QFN-32, Input Voltage:24V, Output Voltage:5.5V, Output Current:30A, Supply Voltage Min:4.5V, Supply Voltage Max:24V, Digital IC Case Style:QFN, No. of Pins:32, Frequency:1MHz, MSL:MSL 1 - Unlimited , RoHS Compliant: Yes 制造商:Linear Technology 功能描述:DP-SWREG/Controller, Digitally Programmable, Multiphase Step-Down DC/DC Controll |
| LTC3883EUH-1#TRPBF | 制造商:Linear Technology 功能描述:IC REG CTRLR BUCK PWM VM 32-QFN |
| LTC3883IUH#PBF | 制造商:Linear Technology 功能描述:DC DC Cntrlr Single-OUT Sync Step Down 4.5V to 24V Input 32-Pin QFN EP 制造商:Linear Technology 功能描述:IC REG CTRLR BUCK PWM VM 32-QFN 制造商:Linear Technology 功能描述:BUCK CNTRL 24V 1MHZ 0.5/5.5V 32QFN 制造商:Linear Technology 功能描述:BUCK, CNTRL, 24V, 1MHZ, 0.5/5.5V, 32QFN 制造商:Linear Technology 功能描述:PWM CONTROLLER, BUCK, 1MHZ, 24V, QFN-32, Input Voltage:24V, Output Voltage:5.5V, Output Current:30A, Supply Voltage Min:4.5V, Supply Voltage Max:24V, Digital IC Case Style:QFN, No. of Pins:32, Frequency:1MHz, MSL:MSL 1 - Unlimited , RoHS Compliant: Yes 制造商:Linear Technology 功能描述:DP-SWREG/Controller, Digitally Programmable, Multiphase Step-Down DC/DC Controll |
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