LP2986_15 Datasheet, PDF (20/33 Pages) Texas Instruments – LP2986 Micropower, 200-mA Ultra-Low-Dropout Fixed or Adjustable Voltage Regulator

LP2986
SNVS137I – MARCH 1999 – REVISED SEPTEMBER 2015
10 Layout
www.ti.com
10.1 Layout Guidelines
For best overall performance, place all circuit components on the same side of the circuit board and as near as
practical to the respective LDO pin connections. Place ground return connections to the input and output
capacitor, and to the LDO ground pin as close to each other as possible, connected by a wide, component-side,
copper surface. The use of vias and long traces to create LDO circuit connections is strongly discouraged and
negatively affects system performance. This grounding and layout scheme minimizes inductive parasitics, and
thereby reduces load-current transients, minimizes noise, and increases circuit stability. A ground reference
plane is also recommended and is either embedded in the PCB itself or located on the bottom side of the PCB
opposite the components. This reference plane serves to assure accuracy of the output voltage, shield noise,
and behaves similar to a thermal plane to spread (or sink) heat from the LDO device. In most applications, this
ground plane is necessary to meet thermal requirements.
10.2 Layout Examples
GND
1
FEEDBACK
2
TAP
3
IN
4
C_IN
DAP
8
SHUTDOWN
7
ERROR
6
SENSE
Error Resistor
5
OUT
C_OUT
Figure 39. WSON Layout with Internal Resistor Divider
GGNNDD
R2
1
FEEDBACK
C_F
IN
2
R1
TAP 3
4
C_IN
DAP
8
SHUTDOWN
7
ERROR
6 SENSE
Error Pullup
Resistor
5
OUT
C_OUT
Figure 40. WSON Layout with External Resistor Divider
20
Submit Documentation Feedback
Product Folder Links: LP2986
Copyright © 1999–2015, Texas Instruments Incorporated