MAX1963EZT150-T Ver la hoja de datos (PDF) - Maxim Integrated

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MAX1963EZT150-T

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

Internal P-Channel Pass Transistor

The MAX1963/MAX1976 feature a 0.33Ω (RDS(ON))

P-channel MOSFET pass transistor. Unlike similar

designs using PNP pass transistors, P-channel

MOSFETs require no base drive, which reduces quies-

cent current. PNP-based regulators also waste consid-

erable current in dropout when the pass transistor

saturates and use high base-drive currents under large

loads. The MAX1963/MAX1976 do not suffer from these

problems and consume only 90µA (typ) of quiescent

current under heavy loads, as well as in dropout.

Shutdown

Pull SHDN low to enter shutdown. During shutdown, the

output is disconnected from the input, an internal 1.5kΩ

resistor pulls OUT to GND, RESET is actively pulled

low, and the supply current drops below 1µA.

RESET Output

The MAX1963/MAX1976 microprocessor (µP) supervisory

circuitry asserts a guaranteed logic-low reset during

power-up, power-down, and brownout conditions down

to +1V. RESET asserts when VOUT is below the reset

threshold and remains asserted for at least tRP after VOUT

rises above the reset threshold of regulation.

Current Limit

The MAX1963/MAX1976 monitor and control the pass

transistor’s gate voltage, limiting the output current to

450mA (min). If the output exceeds ILIM, the MAX1963/

MAX1976 output voltage drops.

Thermal-Overload Protection

Thermal-overload protection limits total power dissipa-

tion in the MAX1963/MAX1976. When the junction tem-

perature exceeds TJ = +165°C, a thermal sensor turns

off the pass transistor, allowing the IC to cool. The ther-

mal sensor turns the pass transistor on again after the

junction temperature cools by 15°C, resulting in a

pulsed output during continuous thermal-overload con-

ditions. Thermal-overload protection safeguards the

MAX1963/MAX1976 in the event of fault conditions. For

continuous operation, do not exceed the absolute maxi-

mum junction-temperature rating of TJ = +150°C.

Operating Region and Power Dissipation

The MAX1963/MAX1976 maximum power dissipation

depends on the thermal 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 P = IOUT ✕ (VIN -

VOUT). The maximum allowed power dissipation is:

PMAX = (TJ(MAX) - TA) / (θJC + θCA)

MAXIMUM OUTPUT CURRENT

vs. INPUT VOLTAGE

(POWER DISSIPATION LIMIT)

400

TA = +85°C

TA = +70°C

300

MAXIMUM RECOMMENDED

200 OUTPUT CURRENT 6-PIN SOT23

100

0

0 0.5 1.0 1.5 2.0 2.5 3.0

(VIN - VOUT) (V)

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)

400

MAXIMUM RECOMMENDED

TA = +85°C

OUTPUT CURRENT 6-PIN TDFN

300

200

100

0

0 0.5 1.0 1.5 2.0 2.5 3.0

(VIN - VOUT) (V)

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

Maximum Output Current vs. Input Voltage

where (TJ(MAX) - TA) is the temperature difference

between the MAX1963/MAX1976 die junction and the

surrounding air, θJC is the thermal resistance of the

junction to the case, and θCA is the thermal resistance

from the case through the PC board, copper traces,

and other materials to the surrounding air. For best

heatsinking, expand the copper connected to the

exposed paddle or GND.

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