MAX1963EZT250-T(2003) Ver la hoja de datos (PDF) - Maxim Integrated

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MAX1963EZT250-T
(Rev.:2003)

Low-Input-Voltage, 300mA LDO Regulators with RESET in SOT and TDFN

Maxim Integrated 

Low-Input-Voltage, 300mA LDO Regulators

with RESET in SOT and TDFN

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

TDFN is 1.951W at TA = +70°C. Figure 3 shows that the

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

and GND. The input capacitor (CIN) lowers the source

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 30mΩ or less to ensure sta-

bility and optimize transient response. Surface-mount

ceramic capacitors have very low ESR and are com-

monly available in values up to 10µF. Connect CIN and

COUT as close to the MAX1963/MAX1976 as possible

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

on-resistance (RDS(ON) = 0.33Ω) multiplied by the load

current (see the Typical Operating Characteristics).

VDROPOUT = VIN - VOUT = 0.33Ω ✕ IOUT

The MAX1963/MAX1976 ground current reduces to 70µA

in dropout.

Selector Guide

VOUT

(V)

SUFFIX

0.75

075

0.85

085

1.00

100

1.10

110

1.20

120

1.30

130

1.50

150

1.60

160

1.80

180

2.50

250

2.85

285

3.00

300

MAX1963

TOP MARK

SOT TDFN

AABA AFQ

—

—

—

—

—

—

AABE

AFU

AABF

AFV

AABG AFW

—

—

AABH

AFX

AABI

AFY

—

—

AABJ

AFZ

MAX1976

TOP MARK

SOT TDFN

AAAQ AGA

AABP

AHD

AABL AGC

AABM AGD

AAAK AGE

AABN

AGF

AAAL AGG

AABO AHC

AAAM AGH

AAAN

AGI

AAAO

AGJ

AAAP

AGK

Chip Information

TRANSISTOR COUNT: 2556

PROCESS: BiCMOS

8 _______________________________________________________________________________________

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