RT8011/A
Layout Guide
C
IN
must be placed between
V
DD
and GND as closer as
possible
V
IN
C
IN
GND
Output capacitor must
be near RT8011
C
OUT
V
OUT
RT8011
PVDD
VDD
PGOOD
FB
R1
C
F
V
OUT
R2
COMP
R
COMP
C
COMP
GND
Connect the FB pin directly to feedback resistors. The
resistor divider must be connected between V
OUT
and
GND.
6
7
8
9
10
5
4
3
2
1
L1
PGND
LX
GND
SYNC
SHDN/RT
LX should be
connected to
Inductor by wide
and short trace,
keep sensitive
compontents away
from this trace
C
IN
must be placed between
V
DD
and GND as closer as
possible
V
IN
C
IN
GND
Output capacitor must
be near RT8011A
C
OUT
V
OUT
RT8011A
PVDD
VDD
5
6
7
8
4
3
2
1
L1
PGND
LX
GND
SHDN/RT
LX should be
connected to
Inductor by wide
and short trace,
keep sensitive
compontents away
from this trace
V
IN
R
OSC
FB
R1
C
F
V
OUT
R2
COMP
R
COMP
C
COMP
R
OSC
GND
Connect the FB pin directly to feedback resistors. The
resistor divider must be connected between V
OUT
and
GND.
Figure 3. RT8011 Layout Guide
Figure 4. RT8011A Layout Guide
Functional Pin Description
Pin Number
RT8011
1
RT8011A
1
Pin Name
Pin Function
Oscillator Resistor Input. Connecting a resistor to ground from this pin sets
SHDN/RT
the switching frequency. Forcing this pin to V
DD
causes the device to be shut
down.
External Clock Synchronization Input. The oscillation frequency can be
2
--
SYNC
synchronized to an external oscillation applied to this pin. When tied to V
DD
,
internal oscillator is selected.
Signal Ground. All small-signal components and compensation components
should connect to this ground, which in turn connects to PGND at one point.
Internal Power MOSFET Switches Output. Connect this pin to the inductor.
Power Ground. Connect this pin close to the (−) terminal of C
IN
and C
OUT
.
Power Input Supply. Decouple this pin to PGND with a capacitor.
Signal Input Supply. Decouple this pin to GND with a capacitor. Normally V
DD
is equal to PVDD.
Power Good Indicator. Open-drain logic output that is pulled to ground when
the output voltage is not within
±12.5%
of regulation point.
Feedback Pin. Receives the feedback voltage from a resistive divider
connected across the output.
Error Amplifier Compensation Point. The current comparator threshold
10
8
COMP
increases with this control voltage. Connect external compensation elements
to this pin to stabilize the control loop.
3
4
5
6
7
8
9
2
3
4
5
6
--
7
GND
LX
PGND
PVDD
VDD
PGOOD
FB
DS8011/A-00 August 2006
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