MIC5376 datasheet(10/24 Pages) MICROCHIP

10 / 24 page

MIC5376/7/8

DS20006080B-page 10



2018 - 2022 Microchip Technology Inc. and its subsidiaries

4.0

APPLICATION INFORMATION

MIC5376, MIC5377, and MIC5378 are low-noise

150 mA LDO regulators. The MIC5376 and MIC5378

include an auto-discharge circuit that is switched on

when the regulator is disabled through the enable pin.

The MIC5376/7/8 regulators are protected from

damage due to fault conditions, offering linear current

limiting and thermal shutdown.

4.1

Input Capacitor

The MIC5376/7/8 are high-performance, high

bandwidth devices. An input capacitor of 1 µF is

required from the input to ground to provide stability.

Low-ESR ceramic capacitors provide optimal

performance at a minimum of space. Additional

high-frequency capacitors, such as small-valued NPO

dielectric-type capacitors, help filter out high-frequency

noise and are good practice in any RF-based circuit.

X5R or X7R dielectrics are recommended for the input

capacitor. Y5V dielectrics lose most of their

capacitance over temperature and are, therefore, not

recommended.

4.2

Output Capacitor

For output voltages ≥ 2.5V, the MIC5376/7/8 require a

minimum 1 µF output capacitor. For output voltages

below 2.5V, a 2.2 µF minimum output capacitor is

required. The design is optimized for use with low-ESR

ceramic chip capacitors. High-ESR capacitors are not

recommended because they may cause high

frequency oscillation. The output capacitor can be

increased, but performance does not improve

significantly with larger capacitance.

X7R/X5R dielectric-type ceramic capacitors are

recommended

because

their

temperature

performance. X7R-type capacitors change capacitance

by 15% over their operating temperature range and are

the most stable type of ceramic capacitors. Z5U and

Y5V dielectric capacitors change value by as much as

50% and 60%, respectively, over their operating

temperature ranges. To use a ceramic chip capacitor

with Y5V dielectric, the value must be much higher than

an X7R ceramic capacitor to ensure the same

minimum capacitance over the equivalent operating

temperature range.

4.3

No-Load Stability

Unlike many other voltage regulators, the MIC5376/7/8

will remain stable and in regulation with no load. This is

especially important in CMOS RAM keep-alive

applications.

4.4

Enable/Shutdown

The MIC5376/7/8 is provided with an active-high

enable pin that allows the regulator to be disabled.

Forcing the enable pin low disables the regulator and

sends it into a “zero” off-mode-current state. In this

state, current consumed by the regulator goes nearly to

zero. Forcing the enable pin high enables the output

voltage. The active-high enable pin uses CMOS

technology and the enable pin cannot be left floating; a

floating enable pin may cause an indeterminate state

on the output.

4.5

Adjustable Regulator Design

The MIC5377/8 adjustable version allows setting the

output voltage down to 1V with the use of two external

feedback resistors.

FIGURE 4-1:

Adjustable Regulator with

Resistors.

4.6

Thermal Considerations

The MIC5376/7/8 are designed to provide 150 mA of

continuous current in a very small package. Maximum

ambient operating temperature can be calculated

based on the output current and the voltage drop

across the part. For example if the input voltage is 3.6V,

the output voltage is 2.8V, and the output current is

150 mA, the actual power dissipation of the regulator

circuit can be determined using the following equation:

EQUATION 4-1:

Because these devices are CMOS and the ground

current is typically <100 µA over the load range, the

power dissipation contributed by the ground current is

<1% and can be ignored for this calculation.

VIN

VOUT

ADJ

GND

U1 MIC5377/8-xxYMT

2.2μF

6.3V

619

VOUT

GND

2.2μF

6.3V

4,5,6,8

VIN

GND

267

OUT = VREF 1+

(

)

VIN VOUT

–





IOUT



VIN

IGND



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