MIC33153 datasheet(14/28 Pages) MICROCHIP

14 / 28 page

MIC33153

DS20006223B-page 14



2019 - 2022 Microchip Technology Inc.

5.0

APPLICATIONS INFORMATION

The MIC33153 is a high performance DC-to-DC step

down regulator offering a small solution size. With the

HyperLight Load® switching scheme, the MIC33153 is

able to maintain high efficiency throughout the entire

load range while providing ultra-fast load transient

response. The following sections provide additional

device application information.

5.1

Input Capacitor

A 2.2µF ceramic capacitor or greater should be placed

close to the VIN pin and PGND pin for bypassing. A

Murata GRM188R60J475ME84D, size 0603, 4.7 µF

ceramic capacitor is recommended based upon

performance, size, and cost. A X5R or X7R

temperature rating is recommended for the input

capacitor. Y5V temperature rating capacitors, aside

from losing most of their capacitance over temperature,

can also become resistive at high frequencies. This

reduces their ability to filter out high frequency noise.

5.2

Output Capacitor

The MIC33153 is designed for use with a 2.2 µF or

greater ceramic output capacitor. Increasing the output

capacitance will lower output ripple and improve load

transient response but could also increase solution size

or cost. A low equivalent series resistance (ESR)

ceramic output capacitor such as the Murata

GRM188R60J475ME84D, size 0603, 4.7 µF ceramic

capacitor is recommended based upon performance,

size, and cost. Both the X7R or X5R temperature rating

capacitors are recommended. The Y5V and Z5U

temperature rating capacitors are not recommended

due to their wide variation in capacitance over

temperature and increased resistance at high

frequencies.

5.3

Compensation

The MIC33153 is designed to be stable with a 4.7 µF

ceramic (X5R) output capacitor.

5.4

Duty Cycle

The typical maximum duty cycle of the MIC33153 is

80%.

5.5

Efficiency Considerations

Efficiency is defined as the amount of useful output

power, divided by the amount of power supplied.

EQUATION 5-1:

Maintaining high efficiency serves two purposes. It

reduces power dissipation in the power supply,

reducing the need for heat sinks and thermal design

considerations and it reduces consumption of current

for battery powered applications. Reduced current

draw from a battery increases the devices operating

time which is critical in hand held devices.

There are two types of losses in switching converters:

DC losses and switching losses. DC losses are simply

the power dissipation of I2R. Power is dissipated in the

high-side switch during the on cycle. Power loss is

equal to the high-side MOSFET RDS(ON) multiplied by

the switch current squared. During the off cycle, the

low-side

N-channel

MOSFET

conducts,

also

dissipating power. Device operating current also

reduces efficiency. The product of the quiescent

(operating) current and the supply voltage represents

another DC loss. The current required driving the gates

on and off at a constant 4 MHz frequency and the

switching transitions make up the switching losses.

FIGURE 5-1:

Efficiency under Load.

Figure 5-1 shows an efficiency curve. From no load to

100 mA, efficiency losses are dominated by quiescent

current losses, gate drive and transition losses. By

using the HyperLight Load® mode, the MIC33153 is

able to maintain high efficiency at low output currents.

Over 100 mA, efficiency loss is dominated by MOSFET

RDS(ON) and inductor losses. Higher input supply

voltages will increase the gate to source threshold on

the internal MOSFETs, thereby reducing the internal

RDS(ON). This improves efficiency by reducing DC

losses in the device. All but the inductor losses are

inherent to the device. In which case, inductor selection

becomes increasingly critical in efficiency calculations.

As the inductors are reduced in size, the DC resistance

(DCR) can become quite significant.



VOUT IOUT



VIN IIN



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







 100



MIC33153 Datasheet(PDF) 14 Page - Microchip Technology

MIC33153 Datasheet(HTML) 14 Page - Microchip Technology

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28

Datasheet Download

Link URL