MCP73830 datasheet(14/22 Pages) MICROCHIP

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MCP73830/L

DS20005049D-page 14

 2011-2014 Microchip Technology Inc.

FIGURE 6-3:

Input Over Voltage Protection Example.

6.1.1.3

Thermal Considerations

The worst-case power dissipation in the battery char-

ger occurs when the input voltage is at the maximum

and the device has transitioned from Preconditioning

mode to Constant Current mode. In this case, the

power dissipation is:

EQUATION 6-1:

Power dissipation with a 5V, ±10% input voltage

source, 200 mA ±10%, and preconditioning threshold

voltage at 6V is:

EQUATION 6-2:

This power dissipation with the battery charger in the

2x2 TDFN-6 package will result in a temperature of

approximately 10.45

C (PCB mounted) above room

temperature.

6.1.1.4

External Capacitors

The MCP73830 is stable with or without a battery load.

In order to maintain good AC stability in Constant Volt-

age mode, a minimum capacitance of 1 µF is

recommended to bypass the VBAT pin to VSS. This

capacitance provides compensation when there is no

battery load. In addition, the battery and interconnec-

tions appear inductive at high frequencies. These

elements are in the control feedback loop during

Constant Voltage mode. Therefore, the bypass capaci-

tance may be necessary to compensate for the

inductive nature of the battery pack.

A minimum of 16V rated 1 µF is recommended to apply

for output capacitor, and a minimum of 25V rated 1 µF

is recommended to apply for input capacitor for typical

applications.

Virtually any good quality output filter capacitor can be

used independent of the capacitor’s minimum Effective

Series Resistance (ESR) value. The actual value of the

capacitor (and its associated ESR) depends on the out-

put load current. A 1 µF ceramic, tantalum or aluminum

electrolytic capacitor at the output is usually sufficient

to ensure stability.

6.1.1.5

Reverse-Blocking Protection

The MCP73830/L provides protection from a faulted or

shorted input. Without the protection, a faulted or

shorted input would discharge the battery pack through

the body diode of the internal pass transistor.

STAT

VDD

VBAT

2 mm x 2 mm DFN

MCP73830

PROG

Regulated

Wall Cube

VSS

0.5



CIN

TVS

SMAJ5.0A/AC

PowerDissipation

DDMAX

PTHMIN

–

 I

REGMAX



Where:

VDDMAX = the maximum input voltage

IREGMAX = the maximum fast charge current

VPTHMIN = the minimum transition threshold

voltage

Pow erDissi pati on

5.5V

3.0V

–

 220mA



0.55 W

TABLE 6-1:

MLCC CAPACITOR EXAMPLE

MLCC

Capacitors

Temperature

Range

Tolerance

X7R

-55

C to + 125C±15%

X5R

-55

C to + 85C

±15%

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