參數(shù)資料
型號(hào): LTC4227CUFD-2#TRPBF
廠商: LINEAR TECHNOLOGY CORP
元件分類: 電源管理
英文描述: POWER SUPPLY MANAGEMENT CKT, PQCC20
封裝: 4 X 5 MM, PLASTIC, MO-220, QFN-20
文件頁(yè)數(shù): 2/20頁(yè)
文件大?。?/td> 307K
代理商: LTC4227CUFD-2#TRPBF
LTC4227-1/LTC4227-2
10
422712f
applicaTions inForMaTion
High availability systems often employ parallel-connected
power supplies or battery feeds to achieve redundancy
and enhance system reliability. Power ORing diodes are
commonly used to connect these supplies at the point of
load, but at the expense of power loss due to significant
diode forward voltage drop. The LTC4227 minimizes this
power loss by using external N-channel MOSFETs for the
pass elements, allowing for a low voltage drop from the
supply to the load when the MOSFETs are turned on (see
Figure 1). When the input source voltage drops below the
outputcommonsupplyvoltage,theappropriateMOSFETis
turnedoff,therebymatchingthefunctionandperformance
of an ideal diode. By adding a current sense resistor and
a Hot Swap MOSFET after the parallel-connected ideal
diode MOSFETs, the LTC4227 enhances the ideal diode
performance with inrush current limiting and overcurrent
protection. This allows the boards to be safely inserted
and removed from a live backplane without damaging
the connector.
Internal VCC Supply
The LTC4227 can operate with input supplies from 2.9V
to 18V at the IN pins. The power supply to the device is
internally regulated at 5V by a low dropout regulator (LDO)
with an output at the INTVCC pin. An internal diode-OR
circuit selects the highest of the supplies at the IN and OUT
pins to power the device through the LDO. The diode-OR
scheme permits the device’s power to be temporarily kept
alive by the OUT load capacitance when the IN supplies
have collapsed or shut off.
AnundervoltagelockoutcircuitpreventsalloftheMOSFETs
from turning on until the INTVCC voltage exceeds 2.2V. A
0.1F capacitor is recommended between the INTVCC and
GND pins, close to the device for bypassing. No external
supply should be connected at the INTVCC pin so as not
to affect the LDO’s operation. A small external load of less
than 500A can be connected at the INTVCC pin.
Turn-On Sequence
The board power supply at the OUT pin is controlled with
external N-channel MOSFETs (MD1, MD2 and MH). The
ideal diode MOSFETs connected in parallel on the supply
side function as a diode-OR, while MH on the load side
acts as a Hot Swap controlling the power supplied to the
output load. The sense resistor, RS, monitors the load
current for overcurrent detection. The HGATE capacitor,
CHG, controls the gate slew rate to limit the inrush current.
Resistor RHG with CHG compensates the current control
loop, while RH prevents high frequency oscillations in the
Hot Swap MOSFET.
Figure 1. Card Resident Diode-OR with Hot Swap Application
BACKPLANE
CONNECTOR
VIN1
12V
VIN2
12V
CARD
CONNECTOR
CPO1
D2ON
ON
FAULT
PWRGD
CL
680F
12V
7.6A
R1
20k
INTVCC
Z2
SMAJ13A
GND
IN1 DGATE1
DGATE2
LTC4227
422712 F01
MD2
SiR462DP
MH
Si7336ADP
RS
0.006
HGATE
OUT
SENSE+ SENSE
CPO2
CCP2
0.1F
IN2
+
R2
137k
R3
100k
R4
100k
RH
10
RHG
47
CHG
15nF
CCP1
0.1F
C1
0.1F
MD1
SiR462DP
EN
CT
0.1F
CF
10nF
Z1
SMAJ13A
TMR
相關(guān)PDF資料
PDF描述
LTC4227IGN-1#TRPBF POWER SUPPLY MANAGEMENT CKT, PDSO16
LTC4227CUFD-1#PBF POWER SUPPLY MANAGEMENT CKT, PQCC20
LTC4227IUFD-2#PBF POWER SUPPLY MANAGEMENT CKT, PQCC20
LTC4227CUFD-2#PBF POWER SUPPLY MANAGEMENT CKT, PQCC20
LTC4227IGN-2#TRPBF POWER SUPPLY MANAGEMENT CKT, PDSO16
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