ncp3122 ON Semiconductor, ncp3122 Datasheet - Page 21

• Manufacturer Part Number: ncp3122
• Description: Dual 2.0 A, Step-down Dc/dc Switching Regulator
• Manufacturer: ON Semiconductor

Sequential Sequencing (First-Up/Last-Down
Sequence Configuration)
starts ramping when the first output voltage is already settled
and its power good signal is set. Figure 39 shows the
NCP3122's configuration and standard waveforms. The
rising slope of both voltages can be selected independently
by the soft-start capacitors' values (C12, C22). When the
Disable
In sequential sequencing mode, the second output voltage
Enable
R_TRACK
C12 C22
EN1
VOUT2
VOUT1
R_T
PG1
PG2
EN1
SEQ1
EN2
SEQ2
TRACK1
TRACK2
AVIN
GND
Figure 39. Sequential Configuration
C3
C22 C12
NCP3122
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C13
R13
R23
C23
GND
C22
NCP3122
C12
21
GND
enable pin is deactivated, the second output voltage
decreases first, followed by the first output voltage. The
control logic is based on the internal power good signal; no
delay is added. The signal has the same threshold values as
the power good signal shown in the electrical table. The
sequential sequencing mode is also called first-up/
last-down and is ideal for DSPs with separate power
supplies for the core and the I/O ports.
SW1
SW2
VIN
VIN
VIN
VIN
VIN
VIN
GND
C1
GND
D11
D21
GND
GND
L21
L11
VIN
C2
GND
R12
R21
R22
R11
GND
GND
C11
C21
GND
GND
OUT1
OUT2