參數資料
型號： LT3958IUHE#PBF
廠商： LINEAR TECHNOLOGY CORP
元件分類： 穩(wěn)壓器
英文描述： SWITCHING REGULATOR, PQCC36
封裝： 5 X 6 MM, LEAD FREE, PLASTIC, QFN-36
文件頁數： 2/28頁
文件大?。?/td> 320K
代理商： LT3958IUHE#PBF
LT3958
10
3958f
APPLICATIONS INFORMATION
INTVCC Regulator Bypassing and Operation
An internal, low dropout (LDO) voltage regulator produces
the 7.2V INTVCC supply which powers the gate driver, as
shown in Figure 1. The LT3958 contains an undervoltage
lockout comparator A8 and an overvoltage lockout com-
parator A9 for the INTVCC supply. The INTVCC undervoltage
(UV) threshold is 3.75V (typical), with 0.15V hysteresis,
to ensure that the internal MOSFET has sufcient gate
drive voltage before turning on. The logic circuitry within
the LT3958 is also powered from the internal INTVCC
supply.
The INTVCC overvoltage threshold is set to be 12.8V
(typical) to protect the gate of the power MOSFET. When
INTVCC is below the UV threshold, or above the overvoltage
threshold, the internal power switch will be turned off and
the soft-start operation will be triggered.
The INTVCC regulator must be bypassed to SGND imme-
diately adjacent to the IC pins with a minimum of 4.7μF
ceramic capacitor. Good bypassing is necessary to supply
the high transient currents required by the MOSFET gate
driver.
In an actual application, most of the IC supply current is
used to drive the gate capacitance of the internal power
MOSFET. The on-chip power dissipation can be signicant
when the internal power MOSFET is being driven at a high
frequency and the VIN voltage is high.
An effective approach to reduce the power consumption of
the internal LDO for gate drive and to improve the efciency
is to tie the INTVCC pin to an external voltage source high
enough to turn off the internal LDO regulator.
If the input voltage VIN does not exceed the INTVCC
overvoltage lockout threshold voltage (12.8V), the INTVCC
pin can be shorted directly to the VIN pin. In this condi-
tion, the internal LDO will be turned off and the gate driver
will be powered directly from the input voltage VIN. With
the INTVCC pin shorted to VIN, however, a small current
(around 16μA) will load the INTVCC in shutdown mode. For
applications that require the lowest shutdown mode input
supply current, do not connect the INTVCC pin to VIN.
In SEPIC or yback applications, the INTVCC pin can be
connected to the output voltage VOUT through a blocking
diode, as shown in Figure 2, if VOUT meets the following
conditions:
1. VOUT < VIN (pin voltage)
2. VOUT < 12.8V (typical)
A resistor RVCC can be connected, as shown in Figure 2, to
limit the inrush current from VOUT. Regardless of whether
or not the INTVCC pin is connected to an external voltage
source, it is always necessary to have the driver circuitry
bypassed with a 4.7μF low ESR ceramic capacitor to ground
immediately adjacent to the INTVCC and SGND pins.
Figure 2. Connecting INTVCC to VOUT
CVCC
4.7μF
VOUT
3958 F02
INTVCC
SGND
LT3958
RVCC
DVCC
相關PDF資料
PDF描述
LT3958EUHE#PBF SWITCHING REGULATOR, PQCC36
LT3958EUHE#TRPBF SWITCHING REGULATOR, PQCC36
LT4180MPGN#PBF POWER SUPPLY SUPPORT CKT, PDSO24
LT4180IGN#PBF POWER SUPPLY SUPPORT CKT, PDSO24
LT4180EGN#TRPBF POWER SUPPLY SUPPORT CKT, PDSO24
相關代理商/技術參數
參數描述
LT3958IUHETRPBF 制造商:LINER 制造商全稱:Linear Technology 功能描述:High Input Voltage, Boost, Flyback, SEPIC and Inverting Converter
LT3959 制造商:LINER 制造商全稱:Linear Technology 功能描述:Wide Input Voltage Range Boost/SEPIC/Inverting Converter with 6A, 40V Switch
LT3959EFE#PBF 制造商:Linear Technology 功能描述:IC REG MULTI CONFIG ADJ 38TSSOP
LT3959EFE#PBF 制造商:Linear Technology 功能描述:DC-DC CONV BOOST/INVERTING TSSOP-38 制造商:Linear Technology 功能描述:DC-DC CONV, BOOST/INVERTING, TSSOP-38
LT3959EFE#TRPBF 制造商:Linear Technology 功能描述:IC REG MULTI CONFIG ADJ 38TSSOP
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