LTC1559 View Datasheet(PDF) - Linear Technology
Part Name
Description
MFG CO.
'LTC1559' PDF : 12 Pages View PDF
LTC4416/LTC4416-1
APPLICATIO S I FOR ATIO
differ by more than 100mV, 100% of the load will come
from the higher of V1 or V2.
The user has the option of using E1 and E2 to disable
one of the two supplies by connecting them to a digital
controller. If E1 is brought low, V1 will no longer supply
current to VS. If E2 is brought high, V2 will no longer sup-
ply current to VS. If E1 is brought low and E2 is brought
high, VS will be disabled.
Figure 5 shows the same application without the shut-
down option. It has one-half the losses of Figure 4 and is
configured for 5V rails.
V1 = 12V
V1
Si7483ADP
Q1 Q2
LTC4416
E1
E1
V1
TO HOST
H1
G1
CONTROLLER
GND GND
VS
VS
E2
E2
G2
H2
V2
V2
V2 = 12V
Figure 4
Q3 Q4
Si7483ADP
4416 F04
Q1
V1
SUPPLY 1
Si7495DP
5V
LTC4416
H1
V1
E1
G1
GND
VS
VS
5V
E2
G2
H2
V2
V2
4416 F05
5V
SUPPLY 2
Q2
Si7495DP
Figure 5. Dual PowerPath for Current Sharing
LTC4416-1
The LTC4416-1 will support all three of the LTC4416
applications without the “soft-off” feature. The only dif-
ference in the two designs is the LTC4416-1 will rapidly
switch off the load from a supply whenever a channel is
disabled. This rapid turn-off feature is desirable when the
supply cannot tolerate certain voltage excursions under
load, or when the load is being protected from a rapidly
changing input supply.
Under and Overvoltage Shutdown
Refer to Figure 6 for an application circuit which disables
the power to the load when the input voltage gets too low
or too high. When VIN starts from zero volts, the load to
the output is disabled until VIN reaches 5.5V. The V1 path is
enabled and the load remains on the input until the supply
exceeds 13.5V. At that voltage, the V2 path is disabled. As
the input falls, the voltage source will be reconnected to
the load when the input drops to 12V and the V2 path is
enabled. Finally, the load will be removed from the input
supply when the voltage drops below 5V.
VIN
VTH2 WITH
HYSTERESIS
R2C
24.9k
GND
R2A
221k
VTH1 WITH
HYSTERESIS
R2E R1C
187k 24.3k
R1A
75k
R1D
182k LTC4416-1
H1
G1
E1
V1
GND
VS
E2
V2
H2
G2
VOUT
TO
LOAD
4416 F06
UV ENABLED AT 5V, VIN RESTORED TO LOAD WHEN VIN RISES TO 5.5V
OV ENABLED AT 13.5V, VIN RESTORED TO LOAD WHEN VIN FALLS TO 12V
Figure 6
Undervoltage
VFAIL
=
VETH
•
R1A +R1c
R1c
=
1.222V
•
75k + 24.3k
24.3k
=
4.99V
( ) R1A +(R1c R1D)
VRESTORE = VETH •
R1c R1D
( ) 75k + 24.3k 182k
= 1.222V • 24.3k 182k = 5.497V
4416fa
10
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