ilc6383 Fairchild Semiconductor, ilc6383 Datasheet - Page 8

• Manufacturer Part Number: ilc6383
• Description: 1-cell To 3-cell Boost Dc-dc Converter With True Load Disconnect, 3.3v, 5v Or Adjustable Output
• Manufacturer: Fairchild Semiconductor

ILC6383
Shut Down
The LBI pin is shared with the shutdown pin. A low voltage
(<0.4V) will put the ILC6383 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 ILC6383 is shut down, the synchronous rectifier
disconnects the output from the input. This ensures that there
is only leakage (I
put so that the battery is not drained when the ILC6383 is
shut down.
Power Good Output (POK)
The POK output of the ILC6383 indicates when V
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 V
pull-up resistor must be connected from the POK output (pin
5 of ILC6383CIR-XX) to either ILC6383’s output or to
some other system voltage source.
8
ON/OFF
Figure 8. Shut Down Control
IN
< 1µA typical) from the input to the out-
R5
R6
LBI/SD
3
ILC6383
2 V
7 GND
OUT
IN
. Note that a
OUT
is
Adjustable Output Voltage Selection
The ILC6383-ADJ allows the output voltage to be set using
a potential divider. The formula for setting the adjustable
output voltage is;
V
where V
Negative Voltage Output
It is possible to generate a negative output voltage as a sec-
ondary supply using the ILC6383. This negative voltage may
be useful in some applications where a negative bias voltage
at low current is required.
1 to 3-cell
ON
OUT
V
OFF
IN
= V
Figure 9. Adjustable Voltage Configuration
47µF
C
FB
IN
FB
is the threshold set which is 1.25V nominal.
V
Figure 10. Negative Output Voltage
R5
R6
IN
x (1+R1/R2), R1+R2 ≤ 100KΩ
15µH
L
-V
0.01µF
PWM
PFM
1A Schottky Diodes
1
2
3
4
L
LBI/SD
V
SEL
IN
ILC6383-ADJ
L
MSOP-8
X
GND
V
LBO
PRODUCT SPECIFICATION
V
OUT
0.01µF
FB
1
2
L
V
8
7
6
5
X
IN
ILC6383
REV. 1.2.6 6/13/02
+
V
OUT
47µF
C
= 1.25 (1+R1/R2)
OUT
R1
R2
V
OUT