MCP73871DM-VPCC Datasheet MCP73871DM-VPCC | P10-P12

MCP73871 Demo Board with Voltage Proportional Current Control User’s Guide

1.2 WHAT IS THE MCP73871 DEMO BOARD WITH VOLTAGE PROPORTIONAL

CURRENT CONTROL?

The MCP73871 Demo Board with Voltage Proportional Current Control demonstrates

the features of Microchip’s MCP73871 “Stand-Alone System Load Sharing and Li-Ion

/ Li-Poly Battery Charge Management Controller”.The MCP73871 Demo Board with

Voltage Proportional Current Control is designed to deliver minimum 1.5A total current

to system load and to a single cell Li-Ion battery at 4.2V preset voltage regulation (4.1V,

4.35V and 4.4V options are also available for MCP73871). The MCP73871 Demo

Board with Voltage Proportional Current Control has one dip switch (S1) with four poles

to control input current limits, enable charge timer and enable charging. The first switch

decides the input power source between AC-DC wall adapter and USB port (AC/USB).

The second switch of S1 determines the 500 mA high-power USB port or the 100 mA

low-power USB port (High/Low), if the first switch of S1 is enabled (ON). The input

current limit is governed by the USB specification when selecting USB on S1 switch.

The maximum fast current when AC is selected on S1 is programmed by the resistor

PROG1

at 1A, and the termination current is set at 100 mA by R

PROG3

(see Figure 1-1).

The MCP73871 Demo Board with Voltage Proportional Current Control offers three

status LED (for charge status outputs and a power-good indicator).

The MCP73871 Demo Board with Voltage Proportional Current Control comes with a

factory preset low-battery indicator (LBO) when input is absent. The preset value is

3.2V and STAT1 LED (Green) will turn ON if the battery voltage is below the threshold

voltage.

The MCP73871 Demo Board with Voltage Proportional Current Control is designed to

cover all the features of the MCP73871 device. A thermistor can be added at test points

TP6 and TP7, but resistor R6 must be removed (see the A.2 “Board – Schematic”).

The board layout easily permit to change the two programmable resistors: R

PROG1

and

PROG3

1.3 WHAT THE MCP73871 DEMO BOARD WITH VOLTAGE PROPORTIONAL

CURRENT CONTROL KIT INCLUDES?

This MCP73871 Demo Board with Voltage Proportional Current Control kit includes:

• One MCP73871 Demo Board with Voltage Proportional Current Control,

102-00244

• Important Information "Read First"

Note: Refer to Table 2-1 for charge status outputs and Figure 2-1 for charge

current setups.

MCP73871 DEMO BOARD WITH

VOLTAGE PROPORTIONAL

CURRENT CONTROL USER’S GUIDE

Chapter 2. Installation and Operation

2.1 INTRODUCTION

The MCP73871 Demo Board with Voltage Proportional Current Control demonstrates

Microchip's standalone linear Li-Ion battery charger with system power path and load

sharing management control solution. The system load is also powered by the Li-Ion

battery when the input power is disconnected. A number of device options allow the

MCP73871 to be utilized in a variety of applications. Please refer to the MCP73871

Data Sheet (DS22090) and/or contact local Microchip supports for additional device

options.

Typical applications for the reference design are in Smart Phones, PDA, Portable

Media Players, MP3 Players, Digital Cameras, Handheld Medical devices, Bluetooth

headsets, Ultra-Mobile PC and Portable Communicators.

2.2 FEATURES

The MCP73871 Demo Board with Voltage Proportional Current Control has the

following features:

• Integrated System Load Sharing

• Voltage Proportional Current Control (VPCC) Input voltage: 5.5V with ±0.5V

tolerance (additional information available in the MCP73871 Data Sheet)

• Input Current Limit Control hardware selected (typical 1650 mA, USB-High

maximum 500 mA, and USB-Low maximum 100 mA)

• Three LEDs to indicate charge status, low battery and power good signal

• Preset Li-Ion battery charge voltage: 4.2V ± 0.5%

• Temperature monitoring is disabled by default, but can be enabled to use with a

NTC thermister (tied at TP6 and TP7 and removing R6)

• Factory preset 0.1C preconditioning current of deeply depleted cells

• Factory preset Safety Timer with Timer Enable feature (by S1 switch)

• Constant Current/Constant Voltage (CC/CV) charge algorithm

• Resistor programmed maximum charge current (R

PROG1

): 1A

• Resistor programmed termination set point (R

PROG3

): 100 mA

• Automatic Charge Termination

• Automatic Recharge

• Internal Thermal Regulation

• Exposed Pad with extra via underneath for better heat dissipations

MCP73871 Demo Board with Voltage Proportional Current Control User’s Guide

2.3 GETTING STARTED

The MCP73871 Demo Board with Voltage Proportional Current Control is fully

assembled and tested for charging a single-cell Li-Ion or Li-Polymer battery with or

without system load.

2.3.1 Power Input and Output Connection

2.3.1.1 POWERING THE MCP73871 DEMO BOARD WITH VOLTAGE

PROPORTIONAL CURRENT CONTROL

1. Connect the positive battery terminal to V

BAT

+ (TP4) and negative battery

terminal to GND (TP1 or TP5).

2. Connect the 5V – 6V DC power supply Negative Terminal to GND (TP1 or TP5).

3. Connect the 5V – 6V DC power supply Positive Terminal to V

(TP2).

4. Connect positive of load to OUT (TP3) on the board and negative of load to GND

(TP1 or TP5). The system load can be a power resistor or E-Load.

5. The maximum current that system load requires should not violate the

specification of Li-Ion battery manufacturer (typical at 1C or less) or 1A for safety

and performance concerns.

6. You should initiate the battery charging cycle when turning CE switch of S1 OFF.

Turning the CE switch ON disables the Li-Ion battery charger function.

7. The S1 switch #1 in OFF position (SEL - “AC-DC”) allows maximum input current

of 1.8A to support both system load and Li-Ion battery charger at 1000 mA fast

charge current rate.

8. The S1 switch #1 in ON position (SEL - “USB”) limits the input current to meet

USB specifications.

9. If switch SEL is in ON position (PROG2), the user has two options for switch #2:

- OFF - limits the total input current to 500 mA

- ON - for maximum input current at 100 mA.

10. If DC power is removed, the load should be supported by the Li-Ion battery.

2.3.2 Programming Resistors

The resistors that connected at R

PROG1

and R

PROG3

pins select the maximum charge

current in constant current mode from ac-dc adapter and termination current,

respectively. The relationship between fast charge current and value of R

PROG1

resistor is illustrated in Figure 2-1. The correspondence of R

PROG1

on MCP73871

Demo Board with Voltage Proportional Current Control is R

. The default value is 1 k,

which sets the maximum charge current at 1A.

For R

PROG3

, the correspondent resistor is R

. A 10 k resistor sets the charge

termination current at 100 mA and a 100 k value results a 10 mA termination point.

Read carefully the additional information on the schematic in A.2 “Board – Sche-

matic”. The boards comes with R

=10 k.

Note 1: For setup/configuration follow the information in Table 2-2.

2: Fast Charge Current and Termination Current can be easily programmed

with various resistors based on Figure 2-1.

3: The Li-Ion battery pack can be replaced with test circuit or electronic load

that can sink current with DC power supply. Refer to Figure 2-2 for

details.

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