LTC2924 Linear Technology, LTC2924 Datasheet - Page 9

• Manufacturer Part Number: LTC2924
• Description: Quad Power Supply Sequencer
• Manufacturer: Linear Technology

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  D  O  N  E 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.
U
CONTROLLER
V
CC
SYSTEM
EARLY*
U
TURN OFF
*V
SEQUENCING SUPPLIES
W
CC
Figure 4. 6-Power Supply Sequencer Block Diagram
EARLY MUST BE ON BEFORE
U
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, I
ing R
For each sequenced power supply, choose a voltage
when the power supply is considered to be On during
OUT1
OUT2
OUT3
OUT4
DONE
FAULT
SHDN
SHDN
SHDN
SHDN
SHDN
SHDN
R
LTC2924
HYS
HYS
GND
PS1
PS2
PS3
PS4
PS5
PS6
V
CC
V
V
V
V
V
V
:
=
OUT
OUT
OUT
OUT
OUT
OUT
0 5
IN1
IN2
IN3
IN4
I
ON
HYS
.
V
2924 F04
; .
0 5
µ ≤
A I
HYS
≤
www.DataSheet4U.com
50
µ
A
HYS
LTC2924
, and calculat-
2924fa
9