sp6649eu/tr Exar Corporation, sp6649eu/tr Datasheet - Page 3

• Manufacturer Part Number: sp6649eu/tr
• Description: Ultra-low Quiescent Current, High Efficiency Boost Dc-dc Regulator
• Manufacturer: Exar Corporation

PIN DESCRIPTION
Rev:001 Date:11/20/03
PIN NUMBER
10
1
2
3
4
5
6
7
8
9
SP6649 Ultra-low Quiescent Current, High Efficiency Boost DC-DC Regulator
PIN NAME
SHDN
LBON
V
GND
P
V
R
LBI
FB
LX
BATT
GND
OUT
LIM
DESCRIPTION
Battery Voltage pin. The startup circuitry runs off of this pin. The
operate circuit also uses this voltage to regulate the off-time
[t
0.62V after a successful startup the SP6649 goes into an undervoltage
lockout mode (UVLO).
down to ground. Use a resistor divider to program the low voltage
threshold for each battery configuration.
Low Battery Output Not pin. Open drain N
current to ground when LBI is below 0.625V.
Resistor Programmable Inductor Peak Current. By connecting a
resistor R
I
(for 1.2A).
to ground to disable all circuitry inside the chip. In shutdown the
output voltage will float down to a diode drop below the battery
potential.
External Feedback pin. Connect this pin to GND for fixed +3.3V
operation. Connect this pin to a resistor voltage divider between V
and GND for adjustable output operation.
Ground pin for the internal regulator bias currents.
Switch ground pin. The inductor charging current flows out of this pin.
Inductor switching node. Connect one terminal of the inductor to the
positive terminal of the battery. Connect the second terminal of the
inductor to this pin. The inductor charging current flows into LX,
through the internal charging N-channel FET, and out the GND pin.
Output Voltage pin. The inductor current flows out of this pin during
the off-time. It is also the internal regulator voltage supply, and
minimum off-time one shot input. Kelvin connect this pin to the
positive terminal of the output capacitor.
Low Battery Input pin. LBI below 0.61V causes the LBON pin to pull
Shutdown Not. Tie this pin to V
PEAK
OFF
=1400/R
= K
OFF
LIM
/ (V
from this pin to ground the inductor peak current is set by
3
LIM
OUT
. The range for R
- V
BATT
)]. When the battery voltage drops below
BATT
LIM
is 4.0K (for 350mA) to 1.17K
for normal operation. Tie this pin
MOS
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output that sinks
OUT