SP6648 datasheet(3/16 Pages) SIPEX

3 / 16 page

Date: 6/7/06 Rev B

SP6648 Ultra-low Quiescent Current, High Efficiency Boost Regulator

PIN DESCRIPTION

PIN NUMBER

PIN NAME

DESCRIPTION

1VBATT

Battery Voltage. The startup circuitry is powered by this pin. Battery

Voltage is used to calculate switch off time: tOFF = KOFF/ (VOUT - VBATT).

When the battery voltage drops below 0.61V the SP6648 goes into an

undervoltage lockout mode (UVLO), where the part is shut down.

LBI

Low Battery Input. LBI below 0.61V causes the SP6648 pin to pull LBON

pin down to ground. Use a resistor divider to program the low voltage

threshold for a specific battery configuration.

LBON

Low Battery Output Not. Open drain NMOS output that sinks current to

ground when LBI is below 0.61V.

4RLIM

Current Limit Resistor. By connecting a resistor RLIM from this pin to

ground the inductor peak current is set by IPEAK=1600/RLIM. The range for

RLIM is 9kΩ (for 180mA) to 1.KΩ (for 1.6A).

SHDN

Shutdown Not. Tie this pin high to VBATT, for normal operation. Pull this

pin to ground to disable all circuitry inside the chip. In shutdown the

output voltage will float down to a diode drop below the battery voltage.

Feedback. Connect this pin to GND for fixed +3.3V operation. Connect

this pin to a resistor voltage divider between VOUT and GND for

adjustable output operation.

GND

Ground. Connect to ground plane.

PGND

Power Ground. 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 PGND pin.

VOUT

Output Voltage. The inductor current flows out of this pin during switch

off-time. It is also used as the internal regulator voltage supply. Connect

this pin to the positive terminal of the output capacitor.

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