參數(shù)資料
型號: LTC3788EGN-1#TRPBF
廠商: LINEAR TECHNOLOGY CORP
元件分類: 穩(wěn)壓器
英文描述: DUAL SWITCHING CONTROLLER, 900 kHz SWITCHING FREQ-MAX, PDSO28
封裝: 0.150 INCH, LEAD FREE, PLASTIC, SSOP-28
文件頁數(shù): 6/30頁
文件大?。?/td> 384K
代理商: LTC3788EGN-1#TRPBF
LTC3788-1
14
37881fb
applicaTions inForMaTion
The Typical Application on the first page is a basic
LTC3788-1applicationcircuit.LTC3788-1canbeconfigured
to use either inductor DCR (DC resistance) sensing or a
discrete sense resistor (RSENSE) for current sensing. The
choicebetweenthetwocurrentsensingschemesislargely
a design trade-off between cost, power consumption and
accuracy. DCR sensing is becoming popular because it
does not require current sensing resistors and is more
power-efficient, especially in high current applications.
However, current sensing resistors provide the most
accurate current limits for the controller. Other external
component selection is driven by the load requirement,
and begins with the selection of RSENSE (if RSENSE is used)
andinductorvalue.Next,thepowerMOSFETsareselected.
Finally, input and output capacitors are selected.
SENSE+ and SENSEPins
The SENSE+ and SENSEpins are the inputs to the cur-
rent comparators. The common mode input voltage range
of the current comparators is 2.5V to 38V. The current
sense resistor is normally placed at the input of the boost
controller in series with the inductor.
The SENSE+ pin also provides power to the current
comparator. It draws ~200A during normal operation.
There is a small base current of less than 1A that flows
into the SENSEpin. The high impedance SENSEinput
to the current comparators allow accurate DCR sensing.
Filter components mutual to the sense lines should be
placed close to the LTC3788-1, and the sense lines should
run close together to a Kelvin connection underneath the
current sense element (shown in Figure 1). Sensing cur-
rent elsewhere can effectively add parasitic inductance
and capacitance to the current sense element, degrading
the information at the sense terminals and making the
programmed current limit unpredictable. If DCR sensing
is used (Figure 2b), sense resistor R1 should be placed
closetotheswitchingnode,topreventnoisefromcoupling
into sensitive small-signal nodes.
Figure 1. Sense Lines Placement with
Inductor or Sense Resistor
(2a) Using a Resistor to Sense Current
(2b) Using the Inductor DCR to Sense Current
Figure 2. Two Different Methods of Sensing Current
VIN
TO SENSE FILTER,
NEXT TO THE CONTROLLER
INDUCTOR OR RSENSE
37881 F01
TG
SW
BG
INDUCTOR
DCR
L
LTC3788-1
INTVCC
BOOST
SENSE+
SENSE
R2
C1
VBIAS
VIN
VOUT
PLACE C1 NEAR SENSE PINS
SGND
37881 F02b
(R1||R2) C1 =
L
DCR
RSENSE(EQ) = DCR
R2
R1 + R2
R1
TG
SW
BG
LTC3788-1
INTVCC
BOOST
SENSE+
SENSE
(OPTIONAL)
VBIAS
VIN
VOUT
SGND
37881 F02a
相關(guān)PDF資料
PDF描述
LTC3789EGN#TRPBF 0.1 A SWITCHING CONTROLLER, 710 kHz SWITCHING FREQ-MAX, PDSO28
LTC3789EUFD#TRPBF 0.1 A SWITCHING CONTROLLER, 710 kHz SWITCHING FREQ-MAX, PQCC28
LTC3789EGN#PBF 0.1 A SWITCHING CONTROLLER, 710 kHz SWITCHING FREQ-MAX, PDSO28
LTC3789IUFD#PBF 0.1 A SWITCHING CONTROLLER, 710 kHz SWITCHING FREQ-MAX, PQCC28
LTC3789IGN#TRPBF 0.1 A SWITCHING CONTROLLER, 710 kHz SWITCHING FREQ-MAX, PDSO28
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