MIC5205 datasheet(11/20 Pages) MICROCHIP

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2017 - 2022 Microchip Technology Inc. and its subsidiaries

DS20005785C-page 11

MIC5205

regulator circuit. For example, when operating the

MIC5205-3.3YM5 at room temperature with a minimum

footprint layout, the maximum input voltage for a set

output current can be determined as follows:

EQUATION 4-3:

The junction-to-ambient thermal resistance for the

minimum footprint is 220°C/W, from Table 4-1. The

maximum power dissipation must not be exceeded for

proper operation. Using the output voltage of 3.3V and

an output current of 150 mA, the maximum input

voltage can be determined. From the Electrical

Characteristics table, the maximum ground current for

150 mA output current is 2500 µA or 2.5 mA.

EQUATION 4-4:

EQUATION 4-5:

EQUATION 4-6:

VIN(MAX) then equates out to 6.23V. Therefore, a 3.3V

application at 150 mA of output current can accept a

maximum input voltage of 6.2V in a SOT-23-5 package.

For a full discussion of heat sinking and thermal effects

on voltage regulators, refer to the Regulator Thermals

section of Microchip’s Designing with Low-Dropout

Voltage Regulators handbook.

4.7

Fixed Regulator Applications

Figure 4-1 includes a 470 pF capacitor for low-noise

operation and shows EN (pin 3) connected to IN (pin 1)

for an application where enable/shutdown is not

required. COUT = 2.2 µF minimum.

FIGURE 4-1:

Ultra-Low Noise Fixed

Voltage Application.

Figure 4-2 is an example of a low-noise configuration

where CBYP is not required. COUT = 1 µF minimum.

FIGURE 4-2:

Low Noise Fixed Voltage

Application.

4.8

Adjustable Regulator Applications

The MIC5205YM5 can be adjusted to a specific output

voltage by using two external resistors (Figure 4-3).

The resistors set the output voltage based on the

following equation:

EQUATION 4-7:

This equation is correct due to the configuration of the

bandgap reference. The bandgap voltage is relative to

the output, as seen in the block diagram. Traditional

regulators normally have the reference voltage relative

to ground and have a different VOUT equation.

Resistor values are not critical because ADJ (adjust)

has a high input impedance, but for best results use

resistors of 470 kΩ or less. A capacitor from ADJ to

ground provides greatly improved noise performance.

PD MAX





125C 25C

–





220C/W

----------------------------------------

455mW

VIN 3.3V

–





150mA



VIN

2.5mA



455mW

VIN 150mA



495mW

–

VIN

2.5mA



950mW

VIN 152.5mA



2.2μF

470pF

VOUT

MIC5205-x.xYM5

VIN

1.0μF

Enable

Shutdown

VOUT

MIC5205-x.xYM5

VIN

VOUT 1.242V R2

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