The MAX1963/MAX1976 deliver up to 300mA and oper-

ate with an input voltage up to +3.6V. However, when

using the 6-pin SOT23 version, high output currents

can only be sustained when the input-output differential

voltage is less than 2V, as shown in Figure 2.

The maximum allowed power dissipation for the 6-pin

maximum input-output differential voltage is not limited

by the TDFN package power rating.

Applications Information

Capacitor Selection and

Regulator Stability

Capacitors are required at the MAX1963/MAX1976

input and output for stable operation over the full tem-

perature range and with load currents up to 300mA.

Connect a 1µF ceramic capacitor between IN and GND

and a 4.7µF low-ESR ceramic capacitor between OUT

impedance of the input supply. Use larger output

capacitors to reduce noise and improve load-transient

response, stability, and power-supply rejection.

The output capacitor’s equivalent series resistance

(ESR) affects stability and output noise. Use output

capacitors with an ESR of 30m

Ω or less to ensure sta-

bility and optimize transient response. Surface-mount

ceramic capacitors have very low ESR and are com-

to minimize the impact of PC board trace inductance.

Noise, PSRR, and Transient Response

The MAX1963/MAX1976 are designed to operate with

low dropout voltages and low quiescent currents in bat-

tery-powered systems while still maintaining good

noise, transient response, and AC rejection. See the

Typical Operating Characteristics for a plot of Power-

Supply Rejection Ratio (PSRR) versus Frequency.

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 filtering techniques.

The MAX1963/MAX1976 load-transient response (see

the Typical Operating Characteristics) shows two com-

ponents of the output response: a near-zero DC shift

from the output impedance due to the load-current

change, and the transient response. A typical transient

response for a step change in the load current from 20mA

to 200mA is 20mV. Increasing the output capacitor’s value

and decreasing the ESR attenuates the overshoot.

Input-Output (Dropout) Voltage

A regulator’s minimum input-output voltage difference

(dropout voltage) determines the lowest usable supply

voltage. In battery-powered systems, this determines the

useful end-of-life battery voltage. Because the

MAX1963/MAX1976 use a P-channel MOSFET pass tran-

sistor, the dropout voltage is a function of drain-to-source

Ω) multiplied by the load

current (see the Typical Operating Characteristics).

The MAX1963/MAX1976 ground current reduces to 70µA

in dropout.

Low-Input-Voltage, 300mA LDO Regulators

8

_______________________________________________________________________________________

Chip Information

TRANSISTOR COUNT: 2556

PROCESS: BiCMOS

MAX1963

TOP MARK

MAX1976

TOP MARK

(V)

SUFFIX

SOT

TDFN

SOT

TDFN

0.75

075

AABA

AFQ

AAAQ

AGA

0.85

085

——

AABP

AHD

1.00

100

——

AABL

AGC

1.10

110

——

AABM

AGD

1.20

120

AABE

AFU

AAAK

AGE

1.30

130

AABF

AFV

AABN

AGF

1.50

150

AABG

AFW

AAAL

AGG

1.60

160

——

AABO

AHC

1.80

180

AABH

AFX

AAAM

AGH

2.50

250

AABI

AFY

AAAN

AGI

2.85

285

——

AAAO

AGJ

3.00

300

AABJ

AFZ

AAAP

AGK

Selector Guide