SC1185 Semtech Corporation, SC1185 Datasheet - Page 9

• Manufacturer Part Number: SC1185
• Description: PROGRAMMABLE SYNCHRONOUS DC/DC CONVERTER/ DUAL LOW DROPOUT REGULATOR CONTROLLER
• Manufacturer: Semtech Corporation

PRELIMINARY - January 6, 1999
© 1999 SEMTECH CORP.
4) The Output Capacitor(s) (Cout) should be located
as close to the load as possible, fast transient load
currents are supplied by Cout only, and connections
between Cout and the load must be short, wide cop-
per areas to minimize inductance and resistance.
5) The SC1185 is best placed over a quiet ground
plane area, avoid pulse currents in the Cin, Q1, Q2
loop flowing in this area. PGNDH and PGNDL should
be returned to the ground plane close to the package.
The AGND pin should be connected to the ground
side of (one of) the output capacitor(s). If this is not
possible, the AGND pin may be connected to the
ground path between the Output Capacitor(s) and the
Cin, Q1, Q2 loop. Under no circumstances should
AGND be returned to a ground inside the Cin, Q1, Q2
loop.
6) Vcc for the SC1185 should be supplied from the 5V
Currents in various parts of the power section
5V
+
PROGRAMMABLE SYNCHRONOUS DC/DC
CONVERTER, DUAL LOW DROPOUT
REGULATOR CONTROLLER
supply through a 10 resistor, the Vcc pin should be
decoupled directly to AGND by a 0.1 F ceramic ca-
pacitor, trace lengths should be as short as possible.
7) The Current Sense resistor and the divider across
it should form as small a loop as possible, the traces
running back to CS+ and CS- on the SC1185 should
run parallel and close to each other. The 0.1 F ca-
pacitor should be mounted as close to the CS+ and
CS- pins as possible.
8) Ideally, the grounds for the two LDO sections
should be returned to the ground side of (one of) the
output capacitor(s).
652 MITCHELL ROAD NEWBURY PARK CA 91320
+
Vout
SC1185A
SC1185
9