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-

ble to minimize the impact of PC board trace induc-

tance.

Noise, PSRR, and Transient Response

The MAX1963A/MAX1976A are designed to operate

with low dropout voltages and low quiescent currents in

battery-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 MAX1963A/MAX1976A load-transient response

(see the

Typical Operating Characteristics) shows two

components 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

MAX1963A/MAX1976A use a p-channel MOSFET pass

transistor, the dropout voltage is a function of drain-to-

the load current (see the

Typical Operating

Characteristics).

The MAX1963A/MAX1976A ground current reduces to

70µA in dropout.

Low-Input-Voltage, 300mA LDO Regulators

with

RESET in SOT and TDFN

8

_______________________________________________________________________________________

MAXIMUM OUTPUT CURRENT

vs. INPUT VOLTAGE

(POWER DISSIPATION LIMIT)

2.5

2.0

1.5

1.0

0.5

100

200

300

400

0

03.0

MAXIMUM RECOMMENDED

OUTPUT CURRENT 6-PIN SOT23

°C

°C

Figure 2. Power Operating Regions for the 6-Pin SOT23:

Maximum Output Current vs. Input Voltage

MAXIMUM OUTPUT CURRENT

vs. INPUT VOLTAGE

(POWER DISSIPATION LIMIT)

2.5

2.0

1.5

1.0

0.5

100

200

300

400

0

03.0

MAXIMUM RECOMMENDED

OUTPUT CURRENT 6-PIN TDFN 3mm x 3mm

°C

Figure 3. Power Operating Regions for the 6-Pin TDFN:

Maximum Output Current vs. Input Voltage