MIC5207 datasheet(12/24 Pages) MICROCHIP

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MIC5207

DS20005719C-page 12



2017 - 2022 Microchip Technology Inc. and its subsidiaries

MIC5207-3.3YM5 at room temperature with a minimum

footprint layout, the maximum input voltage for a set

output current can be determined with Equation 4-3:

EQUATION 4-3:

The junction-to-ambient thermal resistance for the

minimum footprint is 235°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 3000 µA or 3 mA.

EQUATION 4-4:

Where:

EQUATION 4-5:

Then:

EQUATION 4-6:

Resulting in:

EQUATION 4-7:

Therefore, a 3.3V application at 150 mA of output

current can accept a maximum input voltage of 6V 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

Low-Voltage Operation

The MIC5207-1.8 and MIC5207-2.5 require special

consideration when used in voltage-sensitive systems.

They may momentarily overshoot their nominal output

voltages unless appropriate output and bypass

capacitor values are chosen.

During regulator power up, the pass transistor is fully

saturated for a short time, while the error amplifier and

voltage reference are being powered up more slowly

from the output (see Functional Diagrams). Selecting

larger output and bypass capacitors allows additional

time for the error amplifier and reference to turn on and

prevent overshoot.

To ensure that no overshoot is present when starting up

into a light load (100 µA), use a 4.7 µF output

capacitance and 470 pF bypass capacitance. This

slows the turn-on enough to allow the regulator to react

and keep the output voltage from exceeding its nominal

value. At heavier loads, use a 10 µF output

capacitance and 470 pF bypass capacitance. Lower

values of output and bypass capacitance can be used,

depending on the sensitivity of the system.

Applications that can withstand some overshoot on the

output of the regulator can reduce the output capacitor

and/or reduce or eliminate the bypass capacitor.

Applications that are not sensitive to overshoot due to

power-on reset delays can use normal output and

bypass capacitor configurations.

Please note the junction temperature range of the

regulator with an output less than 2.5V fixed and

adjustable is 0°C to +125°C.

4.8

Fixed Regulator Applications

FIGURE 4-1:

Ultra-Low-Noise

Fixed-Voltage Application.

PD MAX





125oC 25oC

–

235oC/W

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

425mW

VIN 3.3V

–





150mA



VIN

3mA



425mW

VIN 150mA 495mW VIN 3mA



–



920mW

VIN 153mA



VIN MAX





6.01V

2.2μF

VOUT

MIC5207-x.xYM5

VIN

470pF

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