3

Rev. 5/26/05,

*Patent Pending

SP6641A/6641B 500mA Alkaline DC/DC Boost Regulator in SOT-23

© Copyright 2002 Sipex Corporation

PIN DESCRIPTION

PIN NO.

PIN NAME

DESCRIPTION

1LX

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 through the GND

pin.

2

GND

Ground pin. The internal regulator bias currents and the inductor

charging current flows out of this pin.

Output voltage sense pin, internal regulator voltage supply, and

minimum off-time one shot input. Kelvin connect this pin to the positive

terminal of the output capacitor, but for SP6641B, use 10Ω series

resistor and 1µF bypass per Figure 1 schematic.

4

SHDN

ground to disable all circuitry inside the chip. In shutdown mode, the

output voltage will float at a diode drop below the battery potential.

Battery voltage pin. The startup circuitry runs off of this pin. The

regulating circuitry also uses this voltage to control the minimum off-

BLOCK DIAGRAM

Internal

Internal

Supply

SHDN

Ref

Block

REFREADY

REF

GND

Internal

Ground

LX

+

-

C

SU

OSC

EN

Min.

+

-

C

FB

SHDN

SHDN

NGATE

DRIVER

CHARGE

R

Q

S

Qn

SUGATE

LX

M

1

ICHN

SP6641

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ITH