Datasheet

LT8582
21
8582f
APPLICATIONS INFORMATION
is close to its regulation voltage. This method allows the
PG pin to disable multiple ICs. Refer to Figure 10 for the
necessary connections. Alternatively, the PG pin may be
used to pull the SS pin of another switching regulator low,
preventing the other regulator from switching.
• The master switch, immune from the flying capaci-
tor current spike (seen only by the slave switch), can
therefore sense the inductor current more accurately.
• Since the slave switch can sustain large current spikes,
the diodes that feed current into the flying capacitors do
not need current limiting resistors, leading to efficiency
and thermal improvements, as well as a smaller solution
size.
High V
OUT
Charge Pump Topology
The LT8582 can be used in a charge pump topology as
shown in Figure 11, multiplying the output of a boost
converter. The master switch (SWA) can be used to drive
the boost converter, while the slave switch (SWB) can
be used to drive one or more charge pump stages. This
topology is useful for high voltage applications including
VFD bias supplies.
Figure 10. Using the Two LT8582 Channels, with Power
Supply Sequencing
PG1
R
UVLO2
R
UVLO1
SET R
UVLO1
AND R
UVLO2
SUCH THAT
VIN1
UVLO
< VIN2
UVLO
SEE CONFIGURABLE UNDERVOLTAGE LOCKOUT
SECTION FOR DETAILS
10k
V
IN
SHDN
SYS
SHDN2SHDN1
LT8582
8582 F10
CH1
MASTER
CH2
SLAVE
CHARGE PUMP AIDED REGULATORS
Designing charge pumps with the LT8582 can offer efficient
solutions with fewer components than traditional circuits
because of the master/slave switch configuration on the
IC. Although the slave switch, SWB, operates in phase
with the master switch, SWA, only the current through the
master switch (SWA) is sensed by the current comparator
(A4 in the Block Diagram). This method of operation by
the master/slave switches can offer the following benefits
to charge pump designs:
• The slave switch, by not performing a current sense
operation like the master switch, can sustain fairly
large current spikes without falsely tripping the current
comparator. In a charge pump, these spikes occur when
the flying capacitors charge up. Since this current spike
flows through SWB, it does not affect the operation of
the current comparator (A4 in the Block Diagram).
SSGND
SYNC
SWB
SWA
LT8582
CHx
8582 F11
PG
RT
V
IN
SHDN
CLKOUT
V
C
FBX
GATE
V
IN
9V TO 16V
100k
576k
80.6K
21k
22µH
383k
4.7µF
2.2µF
2.2µF
2.2µF
2.2µF
2.2µF 1.5nF
47pF
2.2µF
8.06k
2.2µF
V
OUT1
100V
80mA
V
OUT2
66V
120mA
Figure 11. High V
OUT
Charge Pump Topology