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
This configuration would be used where V1 is a 12V power
supply and the V2 power supply is a 4-cell Li-Ion battery
pack. When V1 is 12V, E2 disables the V2 source from
being connected to VS through Q2A and Q2B by forcing
G2 to V2, H2 is open circuit. E1 is connected to a voltage
greater than the VREF to keep the V1 to VS path active. The
VS output can be shut completely off by grounding the E1
input. The LTC4416 takes its power from the higher of V1,
V2 and VS. This configuration will provide power from V1
to VS until the V1 supply drops below 9V.
When V1 drops below 9V, the H2 pin closes to GND, G2
drops to a VCLAMP below V2 and G1 rises to the VS volt-
age level. V2 will supply current to VS until V1 rises above
10.8V. The H1 output will be open until the E1 input drops
below the VREF voltage level.
The V1 VFAIL is determined by:
VFAIL
=
VETH
•
R2A +R2c
R2c
= 1.222V
•
158k + 24.9k
24.9k
=
8.98V
The V1 VRESTORE is determined by:
( ( )) R2A + R2c R2E
VRESTORE = VETH •
R2c R2E
( ) 158k + 24.9k 105k
= 1.222V • 24.9k 105k = 10.81V
V1 is Greater Than V2
Figure 3 illustrates the external resistor configuration for
this case.
This configuration would be used where V1 is a 12V power
supply and the V2 power supply is a 3-cell Li-Ion battery
pack. When V1 is 16V, E1 enables the V1 source as being the
primary supply, thus disabling the V2 supply since V1 > V2.
When E1 > VREF, the H1 output is open. The VS output can be
shut completely off by grounding the H1 input and forcing
E2 > VREF. The LTC4416 takes its power from the higher of
V1, V2 and VS. This configuration will provide power from
V1 to VS until the V1 supply drops below 12V.
V1 = 12V (FAIL)
V1 = 13.5V (RESTORE)
V1
R1A
221k
PRIMARY SUPPLY
R1D R1C
187k 24.9k
LTC4416
E1
V1
GND
GND
G1
E2
VS
H2
G2
H1
V2
SUP75P03_07
Q1 Q2
VS
V2
V2 = 10.8V
BACKUP SUPPLY
Figure 3
Q3
SUP75P03_07
4416 F03
When V1 drops below 12V, the H1 pin closes to GND,
G2 drops to a VCLAMP below V2 and G1 rises to the V1
voltage level. V2 will supply current to VS until V1 rises
above 13.5V. The H2 output will be shorted to GND until
the E2 input goes above the VREF voltage level.
The V1 VFAIL is determined by:
VFAIL
=
VETH
•
R1A +R1c
R1c
=
1.222V
•
221k + 24.9k
24.9k
=
12.07V
The V1 VRESTORE is determined by:
( ( )) R1A + R1c R1D
VRESTORE = VETH •
R1c R1D
( ) =
1.222V
•
221k + 24.9k 187k
24.9k 187k
= 13.51V
Load Sharing
Figure 4 illustrates the configuration for this case.
This configuration would be used where V1 and V2 are
relatively the same voltage. In this case the LTC4416 acts
as two interconnected ideal diode controllers. VS will be
supplied by the higher of the two supplies, V1 and V2. If
V1 and V2 are exactly the same, then 50% of the current
for VS will be supplied by each supply. As the two supplies
4416fa
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