LP2950-N, LP2951-N
SNVS764Q –JANUARY 2000–REVISED DECEMBER 2017
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10 Power Supply Recommendations
The LP2950-N and LP2951-N are designed to operate from an input voltage supply range between 2.3 V and
30 V. The input voltage range provides adequate headroom in order for the device to have a regulated output.
This input supply must be well regulated. If the input supply is noisy, additional input capacitors with low ESR can
help improve the output noise performance.
11 Layout
11.1 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.
11.2 Layout Example
Input
Output
Capacitor
Capacitor
Ground
VIN
OUT
SENSE
IN
VOUT
FEEDBACK
VTAP
Ground
2
3
1
SHUTDOWN
Error Pullup
Resistor
GND
ERROR
VOUT
Input
Capacitor
Output
Capacitor
VOUT
VIN
Figure 56. LP2950 Board Layout
Figure 57. LP2951 VSSOP Board Layout
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