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MAX15029ATB

1.425V to 3.6V Input, 500mA Low-Dropout Regulators with BIAS Input

Maxim Integrated 

MAX15029/MAX15030

1.425V to 3.6V Input, 500mA Low-Dropout

Regulators with BIAS Input

Capacitor Selection and Regulator Stability

Capacitors are required at the MAX15029/MAX15030’s

inputs and outputs for stable operation over the full

temperature range and with load currents up to 500mA.

Connect a 1μF capacitor between IN and ground and

a 2.2μF capacitor with low equivalent series resistance

(ESR) between OUT and ground for 500mA output current.

The input capacitor (CIN) lowers the source impedance

of the input supply. If input supply source impedance is

high, place a larger input capacitor close to IN to prevent

VIN sagging due to load transients. Smaller output capaci-

tors can be used for output currents less than 500mA.

Calculate the minimum COUT as follows:

= C OUT

IOUT(MAX)

×





1µF

0.25A





Operating Region and Power Dissipation

The maximum power dissipation depends on the ther-

mal resistance of the IC package and circuit board, the

temperature difference between the die junction and

ambient air, and the rate of airflow. The power dissipated

in the device is PDISS = IOUT (VIN - VOUT). The pack-

age features an exposed thermal pad on its underside.

This pad lowers the thermal resistance of the package

by providing a direct heat conduction path from the die

to the PCB. Additionally, the ground pins (GND) perform

the dual function of providing an electrical connection to

system ground and channeling heat away. Connect the

exposed backside pad and GND to the system ground

using a large pad or ground plane and multiple vias to the

ground plane layer.

Noise, PSRR, and Transient Response

The MAX15029/MAX15030 are designed to operate

with low-dropout voltages and low quiescent currents

while still maintaining good noise performance, transient

response, and AC rejection (see the Typical Operating

Characteristics). When operating from noisy sources,

improved supply-noise rejection and transient response

can be achieved by increasing the values of the input

and output bypass capacitors and through passive fil-

tering techniques. The MAX15029/MAX15030 load-

transient response graphs (see the Typical Operating

Characteristics) show two components of the output

response: a DC shift from the output impedance due to

the load current change, and the transient response. A

typical transient overshoot for a step change in the load

current from 100mA to 500mA is 10mV. Use ceramic

output capacitors greater than 2.2μF (up to 100μF) to

attenuate the overshoot.

Layout Guidelines

The TDFN package has an exposed thermal pad on its

underside. This pad provides a low thermal resistance

path for heat transfer into the PCB. This low thermally

resistive path carries a majority of the heat away from

the IC. The PCB is effectively a heatsink for the IC. The

exposed pad should be connected to a large ground

plane for proper thermal and electrical performance. The

minimum size of the ground plane is dependent upon

many system variables. To create an efficient path, the

exposed pad should be soldered to a thermal landing,

which is connected to the ground plane by thermal vias.

The thermal landing should be at least as large as the

exposed pad.

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