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LP5910

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SNVSA91E – SEPTEMBER 2015 – REVISED JULY 2017

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Another important consideration is that tantalum capacitors have higher ESR values than equivalent size

ceramics. This means that while it may be possible to find a tantalum capacitor with an ESR value within the

stable range, it would have to be larger in capacitance (which means bigger and more costly) than a ceramic

capacitor with the same ESR value. Also, the ESR of a typical tantalum increases about 2:1 as the temperature

goes from 25°C down to –40°C, so some guard band must be allowed.

8.2.2.6 Remote Capacitor Operation

The LP5910 requires at least a 1-µF capacitor at the OUT pin, but there is no strict requirements about the

location of the capacitor in regards to the pin. In practical designs the output capacitor may be located up to

10 cm away from the LDO. This means that there is no need to have a special capacitor close to the OUT pin if

there is already respective capacitors in the system (like a capacitor at the input of supplied part). The remote

capacitor feature helps user to minimize the number of capacitors in the system.

As a good design practice, keep the wiring parasitic inductance at a minimum, using as wide as possible traces

from the LDO output to the capacitors, keeping the LDO output trace layer as close as possible to ground layer

and avoiding vias on the path. If there is a need to use vias, implement as many vias as possible between the

connection layers. It is recommended to keep parasitic wiring inductance less than 35 nH. For the applications

with fast load transients, an input capacitor is recommended, equal to or larger to the sum of the capacitance at

the output node, for the best load-transient performance.

8.2.2.7 No-Load Stability

The LP5910 remains stable, and in regulation, with no external load.

8.2.2.8 Enable Control

The LP5910 may be switched to an ON or OFF state by a logic input at the EN pin. A voltage on this pin greater

When the EN pin is low, the regulator output is off and the device typically consumes less than 1 µA.

to ground.

If the application does not require the use of the shutdown feature, the EN pin can be tied directly to the IN pin to

keep the regulator output permanently on.

An internal 1-MΩ pulldown resistor ties the EN input to ground, ensuring that the device remains off if the EN pin

is left open circuit. To ensure proper operation, the signal source used to drive the EN pin must be able to swing

Table 2. Recommended Output Capacitor Specification

PARAMETER

TEST CONDITIONS

MIN

NOM

MAX

UNIT

Capacitance for stability

0.7

1

10

µF

ESR

5

500

mΩ

8.2.2.9 Power Dissipation

Knowing the device power dissipation and proper sizing of the thermal plane connected to the tab or pad is

critical to ensuring reliable operation. Device power dissipation depends on input voltage, output voltage, and

load conditions and can be calculated with Equation 1.

(1)

Power dissipation can be minimized, and greater efficiency can be achieved, by using the lowest available

voltage drops result in better dynamic (that is, PSRR and transient) performance.

On the WSON (DRV) package, the primary conduction path for heat is through the exposed power pad to the

PCB. To ensure the device does not overheat, connect the exposed pad, through thermal vias, to an internal

ground plane with an appropriate amount of copper PCB area .

On the DSBGA (YKA) package, the primary conduction path for heat is through the four bumps to the PCB.