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ILC6382CIR-33

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

Impala Linear Corporation 

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

VIN

R1

R2

3

+

LBI/SD

-

ILC6382

8

VOUT

1.25V

Internal

Reference

7 GND

Figure 7: VLBI < 1.25V

The following equation is used when VIN is lower than

1.25V:

R1 = R2 x [(VREF - VIN) / (VOUT - VREF)],

where VREF = 1.25V (nom.)

This equation can also be derived using voltage divider for-

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

there is only leakage (IIN < 1µA typical) from the input to the

output so that the battery is not drained when the ILC6382

is shut down.

Power Good Output (POK)

The POK output of the ILC6382 indicates when VOUT is

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

has risen to typically 95% of the specified VOUT. Note that a

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;

VOUT = VFB x (1+R1/R2)

Where VFB is the threshold set which is 1.25V nominal.

CIN

L

10µF

VIN

1 to 3-cell

ON

OFF

15µH

R5

R6

ILC6382-ADJ

1

LX

2 VIN

VOUT 8

GND 7

3 LBI/SD LBO 6

4 SYNC

VFB

5

Ext Sync

(Connect to GND if unused)

MSOP-8

+

10µF

COUT

VOUT

R1

R2

VOUT = 1.25 (1+R1/R2)

Figure 9: Adjustable Voltage Configuration

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.

1A Schottky Diodes

-V

0.01µF

ON/OFF

2 VIN

ILC6382

R5

3

LBI/SD

R6

7 GND

0.01µF

L

ILC6382

1 LX

VIN

2 VIN

Figure 10: Negative Output Votlage

Figure 8: Shut Down Control

Impala Linear Corporation

ILC6382 1.5

(408) 574-3939 www.impalalinear.com

Oct 1999 8

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