sc1109acstrt Semtech Corporation, sc1109acstrt Datasheet - Page 9

• Manufacturer Part Number: sc1109acstrt
• Description: Sc1109 Synchronous Pwm Controller With Dual Low-dropout Regulator Controllers
• Manufacturer: Semtech Corporation

4) The Output Capacitor(s) (Cout) should be located as
close to the load as possible, fast transient load cur-
rents sre supplied by Cout only, and connections between
Cout and the load must be short, wide copper areas to
minimize inductance and resistance.
5) The SC1109 is best placed over a quiet ground plane
area, avoid pulse currents in the Cin, Q1, Q2 loop flowing
in this area. GND should be returned to the ground plane
close to the package and close to the ground side of
(one of) the output capacitor(s). If this is not possible,
the GND pin may be connected to the ground path be-
tween the Output Capacitor(s) and the Cin, Q1, Q2 loop.
Under no circumstances should GND be returned to a
ground inside the Cin, Q1, Q2 loop.
POWER MANAGEMENT
Application Information (Cont.)
2004 Semtech Corp.
5V
+
9
6) BST for the SC1109 should be supplied from the 12V
supply, the BST pin should be decoupled directly to GND
by a 0.1mF ceramic capacitor, trace lengths should be as
short as possible. If a 12V supply is not available, a classi-
cal boot strap method could be implemented to achieve
the upper MOSFETs gate drive.
7) The Phase connection should be short .
8) Ideally, the grounds for the two LDO sections should
be returned to the ground side of (one of) the output
capacitor(s).
+
Vout
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SC1109