LTC4223 LINER [Linear Technology], LTC4223 Datasheet - Page 10

• Manufacturer Part Number: LTC4223
• Description: Dual Ideal Diode and Hot Swap Controller
• Manufacturer: LINER [Linear Technology]

applicaTions inForMaTion
LTC4228-1/LTC4228-2
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 LTC4228 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. When
an input source voltage drops below the output common
supply voltage, the appropriate MOSFET is turned off,
thereby matching the function and performance of an ideal
diode. By adding a current sense resistor in between the
two external MOSFETs that are separately controlled, the
LTC4228 enhances the ideal diode performance with inrush
current limiting and overcurrent protection (see Figure 1).
This allows the boards to be safely inserted and removed
from a live backplane without damaging the connector.
Internal V
The LTC4228 can operate with input supplies from 2.9V
to 18V at the IN pins. The power supply to the device is
10
V
12V
CC
IN1
V
12V
IN2
Supply
R2
137k
R1
20k
R3
20k
R4
137k
C
10nF
C
10nF
F1
F2
BULK
SUPPLY
BYPASS
CAPACITOR
C1
0.1µF
ON1
INTV
GND
ON2
BULK
SUPPLY
BYPASS
CAPACITOR
Figure 1. µTCA Application Supplying 12V Power to Two µTCA Slots
CC
CPO1
CPO2
C
0.1µF
C
0.1µF
CP1
CP2
IN1
IN2
Si7336ADP
Si7336ADP
DGATE1
DGATE2
M
M
D1
D2
SENSE1
SENSE2
LTC4228
0.004
0.004
R
+
S1
R
+
SENSE1
S2
SENSE2
–
Si7336ADP
–
HGATE1
Si7336ADP
M
HGATE2
M
H1
R
10
H2
internally regulated at 5V by a low dropout regulator (LDO)
with an output at the INTV
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.
An undervoltage lockout circuit prevents all of the MOSFETs
from turning on until the INTV
0.1µF capacitor is recommended between the INTV
GND pins, close to the device for bypassing. No external
supply should be connected at the INTV
to affect the LDO’s operation. A small external load of less
than 500µA can be connected at the INTV
Turn-On Sequence
The board power supply at the OUT pin is controlled with
two external N-channel MOSFETs (M
M
M
power supplied to the output load. The sense resistor, R
H1
R
10
H2
D
H
on the supply side functions as an ideal diode, while
on the load side acts as a Hot Swap controlling the
R
47
R
47
HG2
C
15nF
HG1
HG2
C
15nF
STATUS1
PWRGD1
PWRGD2
STATUS2
HG1
FAULT1
FAULT2
OUT1
OUT2
TMR1
TMR2
EN1
EN2
R5
100k
R8
100k
C
47nF
T2
R6
100k
R9
100k
V
V
SENSE1 +
SENSE2 +
C
47nF
T1
R7
100k
R10
100k
CC
BACKPLANE
CC
pin. An internal diode-OR
voltage exceeds 2.2V. A
PLUG-IN
PLUG-IN
CARD 1
CARD 2
D
, M
+
422812 F01
CC
H
+
CC
). The MOSFET
C
1600µF
C
1600µF
L1
L2
pin so as not
12V
7.6A
12V
7.6A
pin.
CC
422812f
and
S
,