1-Cell to 3-Cell Boost with True Load Disconnect, 3.3V, 5V, or Adjustable Output

Impala Linear Corporation

8

(408) 574-3939

www.impalalinear.com

Oct 1999

ILC6382 1.5

1.25V:

This equation can also be derived using voltage divider for-

mula across R2. A typical value for R2 is 100k

Ω. Note that

the low battery detector does not operate when the

ILC6382 is in PFM mode or in shutdown.

Shut Down

The LBI pin is shared with the shutdown pin. A low voltage

(<0.4V) will put the ILC6382 into a power down state. The

simplest way to implement this is with an FET across R6 as

shown in figure 8. Note that when the device is not in PWM

mode or is in shutdown the low battery detector does not

operate.

When the ILC6382 is shut down, the synchronous rectifier

disconnects the output from the input. This ensures that

output so that the battery is not drained when the ILC6382

is shut down.

Power Good Output (POK)

within the regulation tolerance of the set output voltage.

POK output is an open drain device output capable of sink-

ing 2mA. It will remain pulled low until the output voltage

pull-up resistor must be connected from the POK output

(pin 5 of ILC6382CIR-XX) to either ILC6382's output or to

some other system voltage source.

Adjustable Output Voltage Selection

The ILC6382-ADJ allows the output voltage to be set using

a potential divider. The formula for setting the adjustable

output voltage is;

Negative Voltage Output

It is possible to generate a negative output voltage as a sec-

ondary supply using the ILC6382. This negative voltage

may be useful in some applications where a negative bias

voltage at low current is required.

V

OUT

8

R2

3

LBI/SD

V

IN

R1

ILC6382

+

-

1.25V

Internal

Reference

GND

7

ON/OFF

R5

R6

LBI/SD

3

ILC6382

7 GND

10

µF

ON

OFF

V

IN

1 to 3-cell

R5

R6

15

µH

Ext Sync

(Connect to GND if unused)

L

10µF

C

OUT

R1

R2

ILC6382-ADJ

MSOP-8

L

X

V

IN

LBI/SD

SYNC

GND

LBO

V

FB

V

OUT

V

OUT

V

1

2

3

4

8

7

6

5

C

IN

+

1

2

L

L

X

V

IN

V

IN

ILC6382

0.01µF

0.01µF

-V

1A Schottky Diodes

Figure 8: Shut Down Control

Figure 9: Adjustable Voltage Configuration

Figure 10: Negative Output Votlage