MIC833 Ver la hoja de datos (PDF) - Micrel

Número de pieza

componentes Descripción

Fabricante

MIC833

Comparator and Reference with Adj. Hystersis

Micrel 

MIC833

Example Application

The battery charger of Figure 3 uses the MIC833 to detect a

low-battery voltage condition (VDIS) and enables a constant-

current source (ICHG). Charging current is enabled until a

charged-battery voltage condition (VCHG) is detected; at

which time the charging-current source is disabled.

Diode D1 was added to Figure 3 to ensure the disabled

current source does not draw battery current. Whether or not

D1 is required is a function of the output stage of the current

source and how it is disabled.

Micrel

The circuitry of Figure 3 is deliberately generalized to imply

flexibility of application. Depending on the application, it may

not be possibly to power the MIC833 from the charger supply

voltage, see Note 2. It may be necessary to provide a

separate voltage regulator, or a resistive voltage divider to

reduce the VDD applied to the MIC833. The part can be

supplied by the battery voltage (VBAT) if this voltage is never

lower than 1.5V, the minimum operating VDD of the part.

Voltage thresholds, VDIS and VCHG, are programmed as

described in the appropriate above paragraph.

Charger

Supply

Voltage

Constant-Current

Source Note 1

IN OUT

D1

EN GND

Battery

VDIS

R2

VCHG

R3

Note 2

MIC833

VDD OUT

LTH

HTH GND

R4

100k

VBATT

(to load)

0.1µF

Note 1. D1 may not be required.

It is shown here to

indicate the disabled

current source should

not load the battery.

Note 2. VDD of the MIC833 is

limited to 5.5V maximum.

The part can be powered

by VBAT if the battery is

never discharged below

VDD(min) = 1.5V

Figure 3. Battery Charger

MIC833

6

September 2001

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