SC402B View Datasheet(PDF) - Semtech Corporation
Part Name
Description
MFG CO.
'SC402B' PDF : 32 Pages View PDF
SC402B
Pin Descriptions
Pin #
1
2
3
4, 30, PAD 1
5
6, 9-11,
PAD 2
7
8
12
Pin Name Pin Function
FB
Feedback input for switching regulator used to program the output voltage — connect to an external resis-
tor divider from VOUT to AGND.
VOUT
Switcher output voltage sense pin — also the input to the internal switch-over between VOUT and VLDO.
The voltage at this pin must be less than or equal to the voltage at the VDD pin.
VDD
Bias supply for the IC — when using the internal LDO as a bias power supply, VDD is the LDO output. When
using an external power supply as the bias for the IC, the LDO output should be disabled.
AGND
Analog ground
FBL
Feedback input for the internal LDO — used to program the LDO output. Connect to an external resistor
divider from VDD to AGND.
VIN
Input supply voltage
SS
The soft start ramp will be programmed by an internal current source charging a capacitor on this pin.
Bootstrap pin — connect a capacitor of at least 100nF from BST to LX to develop the floating supply for the
BST
high-side gate drive.
DH
High-side gate drive
13
LXBST
LX Boost — connect to the BST capacitor.
23-25, PAD 3
LX
Switching (phase) node
14
DL
Low-side gate drive
15-22
26
27
PGND
PGOOD
ILIM
Power ground
Open-drain power good indicator — high impedance indicates power is good. An external pull-up
resistor is required.
Current limit sense pin — used to program the current limit by connecting a resistor from ILIM to LXS.
28
LXS
LX sense — connects to RILIM
29
EN/PSV
Enable/power save input for the switching regulator — connect to AGND to disable the switching regulator,
connect to VDD to operate with power save mode and float to operate in forced continuous mode.
31
TON
On-time programming input — set the on-time by connecting through a resistor to AGND
32
ENL
Enable input for the LDO — connect ENL to AGND to disable the LDO. Drive with logic signal for logic con-
trol, or program the VIN UVLO with a resistor divider between VIN, ENL, and AGND.
14
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