LTC2924C(RevA) データシートの表示（PDF） - Linear Technology
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LTC2924C Datasheet PDF : 20 Pages
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LTC2924
APPLICATIO S I FOR ATIO
Up to five supplies can be sequenced to a sixth master
supply by a single LTC2924 (Figure 4). The turn on of the
first power supply is sensed by the ON pin. Power sup-
plies two through five are enabled by the OUT1 through
OUT4 pins, and their turn on sensed by the IN1 through
IN4 pins respectively. The last power supply is enabled
by the DONE pin, which is generally connected through
an inverter. This application is used where power supplies
are sequentially sequenced on and the turn off is simulta-
neous. Multiple LTC2924s can be cascaded to facilitate
sequencing of eight or more power supplies. See the
Cascading Multiple LTC2924s section.
Selecting the Hysteresis Current and IN Pin Feedback
Resistors
The IN1-IN4 pins are connected to a sequenced power
supply with a resistive divider. The resistors are calculated
by first selecting a hysteresis current, IHYS, and calculat-
ing RHYS:
RHYS
=
0.5V
IHYS
;
0.5µA
≤
IHYS
≤
50µA
For each sequenced power supply, choose a voltage
when the power supply is considered to be On during
PS1
SHDN VOUT
PS2
SHDN VOUT
PS3
SHDN VOUT
PS4
SHDN VOUT
PS5
SHDN VOUT
PS6
SHDN VOUT
VCC EARLY*
SYSTEM
CONTROLLER
VCC
OUT1
ON
LTC2924
OUT2
IN1
OUT3
IN2
OUT4
IN3
TURN OFF
*VCC EARLY MUST BE ON BEFORE
SEQUENCING SUPPLIES
DONE
FAULT
GND
IN4
2924 F04
Figure 4. 6-Power Supply Sequencer Block Diagram
2924fa
9
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