ACE527H datasheet(11/16 Pages) ACE

11 / 16 page

ACE527H

Low Noise, High PSRR LDORegulator

VER 1.3

Application Information

Capacitors Selection

Select carefully the external capacitors carefully to ensure stability and performance. Place the externally

capacitors close to the IC with a distance no longer than 0.5 inches.

The input capacitor C

IN with larger value and lower ESR (equivalent series resistance) provides better

PSRR and line-transient response.

The ACE527H is specifically designed to work with low ESR ceramic output capacitor in space-saving

and performance consideration. A 1uF ceramic capacitor is adequate for stable operation. However, for

best load and line transient response, output capacitor larger than 4.7uF is recommended.

Power Supply Rejection Ration (PSRR)

PSRR is a measure of how well a circuit rejects ripple coming from the input power supply at various

frequencies and is very critical in many RF and wireless applications. PSRR is defined as the gain from

the input ripple to output ripple over a wide frequency range (10Hz to 10MHz), Note that at heavy load

measuring, ∆VIN will cause temperature deviation. Temperature will cause ∆VOUT voltage. So the heavy

load PSRR measuring includes temperature effect.

Thermal Consideration

The maximum power dissipation is specified as:

where T

J(MAX) is the maximum operation junction temperature, TA is the ambient temperature and θJA is the

junction to ambient thermal resistance.

The ACE527H features thermal protection that shuts down the IC if the junction temperature is higher

than 160℃.

However, the power dissipation should be well designed to keep the continuous junction temperature

below 125℃ for maximum reliability.

JA depends on the thermal resistance of the package, PCB layout, surrounding airflow. For SOT-23-5

package, the thermal resistance θ

JA is 250℃/W on the standard JEDEC 51-3 single layer thermal test

board. The maximum power dissipation at TA = 25℃ can be calculated as:

ACE527H Datasheet(PDF) 11 Page - ACE Technology Co., LTD.