MP2661 datasheet(33/35 Pages) MPS

33 / 35 page

MP2661 – 0.5A, 1-CELL CHARGER W/ I2C CONTROL AND POWER PATH

MP2661 Rev. 1.03

www.MonolithicPower.com

4/9/2018

MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited.

APPLICATION INFORMATION

Selecting a Resistor for the NTC Sensor

NTC uses a resistor divider from the input

source (VDD) to sense the battery temperature.

The two resistors (RT1and RT2)allow the high

temperature limit and low temperature limit to

be programmed independently. In other words,

the IC can fit most types of NTC resistors and

different

temperature

operation

range

requirements with the two extra resistors.

RT1and RT2depend on the type of the NTC

resistor and can be calculated with Equation (1)

and Equation (2):

















COLD

HOT

NTCH

NTCL

HOT

COLD HOT

NTCL

COLD

COLD HOT

NTCH

(1)



COLD

NTCL

COLD

1-V

R(R //R

)

(2)

Where RNTCH is the value of the NTC resistor at

a high temperature of the required temperature

operation range, and RNTCL is the value of the

NTC resistor at a low temperature.

Selecting the External Capacitor

Like most low-dropout regulators, the MP2661

requires external capacitors for regulator

stability and voltage spike immunity. The device

is specifically designed for portable applications

requiring minimum board space and small

components.

These

capacitors

must

correctly selected for optimal performance.

An input capacitor is required for stability. A

capacitor at least 1µF must be connected

between IN and GND for stable operation over

the entire load current range. There can be

more output capacitance than input as long as

the input is at least 1µF.

The IC is designed specifically to work with a

very small ceramic output capacitor(typically

2.2µF). A ceramic capacitor with X5R or X7R

type dielectrics at least2.2µF is suitable in the

MP2661 application circuit. For the MP2661,

the output capacitor should be connected

between SYS and GND with thick traces and a

small loop area.

A capacitor from BATT to GND is also

necessary for the MP2661, and the typical

capacitance value is 2.2µF. A ceramic capacitor

with X5R or X7R type dielectrics at least 2.2µF

is suitable for the application circuit.

A capacitor between VDD and GND is used to

stabilize the VDD voltage to power the internal

control and logic circuit. The typical value of this

capacitor is 100nF.

PCB Layout Guidelines

Efficient PCB layout is critical for stable

operation. For best results, follow the guidelines

below.

1. Place the external capacitors as close to the

IC as possible to ensure the smallest input

inductance and ground impedance.

2. Place the PCB trace connecting the

capacitor between VDD and GND very

close to the IC.

3. Keep the AGND for the I2C wire clean and

away from PGND.

4. Place the I2C wire in parallel.

MP2661 Datasheet(PDF) 33 Page - Monolithic Power Systems

MP2661 Datasheet(HTML) 33 Page - Monolithic Power Systems

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 29 30 31 32 33 34 35

Datasheet Download

Link URL