LPA2164ASOF datasheet(11/15 Pages) POWER

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Preliminary Datasheet

LPA2164A

LPA2164A–00

Version 1.0 May.-2013

Email: marketing@lowpowersemi.com

www.lowpowersemi.com

Page 11 of 15

into the output drive signal. This noise is from the

internal analog reference to the amplifier, which

appears as degraded PSRR and THD+N.

How to reduce EMI

A simple solution is to put an additional capacitor

220pF at power supply terminal for power line. The

traces from amplifier to speakers should design as

short as we can.

Applications Information(for Boost)

The LP2164A integrates a 1200KHz fixed frequency,

current-mode regulation architecture to regulate the

boost convertor output voltage. The LP2164A

measures the output voltage through an external

resistive voltage divider and compares that to the

internal 0.6V reference to generate the error voltage

to the inductor current to regulate the output voltage.

The use of current-mode regulation improves

transient response and control loop stability.

When the boost convertor is disabled (EN=Low),

both power switches are off. There is no current path

from SW to OUT. Therefore, the output voltage

discharges to ground. When the boost convertor is

enabled (EN=High), a limited start-current charges

the output voltage rising to SW, then TH part

operates in force PWM mode for regulating the

output voltage to the target value. At the beginning of

each cycle, the N-channel MOSFET switch is turned

on, forcing the inductor current to rise. The current at

the source of the switch is internally measured and

converted to a voltage by the current sense amplifier.

That voltage is compared to the error voltage. When

the inductor current rises sufficiently, the PWM

comparator turns off the switch, forcing the inductor

current to the output capacitor which forces the

inductor current to decrease. The peak inductor

current is controlled by the error voltage. Thus the

output voltage controls the inductor current to satisfy

the lode.

Setting the Output Voltage

Set the output voltage by selecting the resistive

voltage divider ratio. The voltage divider drops the

output voltage to the 0.6V feedback voltage. Use a

100K resistor for R2 of the voltage divider. Determine

the high-side resistor R1 by the equation:

Vout=(R1/R2+1) x VFB

Vout=(R1/R2+1) x 0.6V

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