MIC833

Micrel

MIC833

6

January 2000

Example Application

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

low-battery voltage condition (V

current source (I

charged-battery voltage condition (V

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.

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 (V

lower than 1.5V, the minimum operating V

Voltage thresholds, V

described in the appropriate above paragraph.

VDD

R4

100k

Battery

(to load)

D1

Note 1

Note 2

Constant-Current

Source

R2

R3

MIC833

0.1

µF

LTH

HTH

OUT

GND

IN

OUT

GND

EN

Charger

Supply

Voltage

Note 1. D1 may not be required.

It is shown here to

indicate the disabled

current source should

not load the battery.

limited to 5.5V maximum.

The part can be powered

never discharged below

Figure 3. Battery Charger