ncp3121 ON Semiconductor, ncp3121 Datasheet - Page 21

• Manufacturer Part Number: ncp3121
• Description: Dual 3.0 A, Step-down Dc/dc Switching Regulator
• Manufacturer: ON Semiconductor

Daisy Chain Operation
to the EN of the first-up/last-down power output. Each
output in the chain has its power-up delay set by the
level, the next voltage rail is enabled and its rise is monitored
until it has reached the power good trip point. At this point,
the next voltage rail is enabled. This continues until all
DISABLE
The last-up/first-down power output has its SEQ pin tied
When the first voltage rail has reached a specific voltage
ENABLE
EN
Vout3
Vout4
Vout1
Vout2
Figure 38. Simplified Drawing of Daisy-chained NCP3121's
SEQ
NCP3121
TRACK
SS
C1 C2
C1
C3
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EN
C4
SEQ
NCP3121
NCP3121
TRACK
21
SS
soft-start ramp-up of the supply. This feeds its EN and its
power-down delay set by the soft-start ramp-down of the
supply that feeds its SEQ pin.
voltage rails have been enabled (see Figure 39).
Power-down sequencing is just the opposite of the
power-up sequence.
C2
C4
C3
EN
SEQ
C2 C1
NCP3121
TRACK
SS
C3
EN
SEQ
NCP3121
TRACK
SS
C4