ST619LB SERIES

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OPERATING PRINCIPLE

The ST619LB is able to provide a regulated 5V

output from a 2V to 3.6V (two battery cells) input.

Internal charge pump and external capacitors

generate the 5V output, eliminating the need for

inductors. The output voltage is regulated to 5V,

±4% by a pulse skipping controller that turns on

the charge pump when the output voltage begins

to drop. To maintain the greatest efficiency the

internal charge pump of the device operates as a

to 2.5V.

switches between doubler and tripler mode on

To further enhance the efficiency over the input

range, an internal comparator selects the higher of

80%.

In tripler mode (see block diagram), when the S1

switches close, the S2 switches open and

second half of the cycle, C1 and C2 are connected

in series between IN and OUT when the S1

switches open and S2 switches close. In the

doubler mode only C2 is used. During one

oscillator cycle, energy is transferred from the

input to the charge pump capacitors, and then

from the charge pump capacitors to the output

capacitors and load. The number of cycles within

a given time frame increases as the load

increases

or

as

the

input

supply

voltage

decreases. In the limiting case , the charge pumps

operate continuously, and the oscillator frequency

is nominally 500kHz.

Shut Down Mode

The ST619LB enters low power shut down mode

when SHDN is a logic high. In shut down mode,

0V. The SHDN pin is connected to ground for

normal operation. SHDN is a CMOS compatible

input.

ABSOLUTE MAXIMUM RATINGS

Absolute Maximum Ratings are those values beyond which damage to the device may occur. Functional operation under these condition is

not implied.

THERMAL DATA

(*) This value depends from thermal design of PCB on which the device is mounted.

Symbol

Parameter²

Value

Unit

DC Input Voltage

-0.3 to 5.5

V

Output Voltage

-0.3 to 5.5

V

Shutdown Input Voltage

V

Output Current Continuous

120

mA

Storage Temperature Range

-55 to +150

°C

Operating Junction Temperature Range

-40 to +85

°C

Symbol

Parameter

SO-8

DIP-8

Unit

Thermal Resistance Junction-ambient (*)

160

100

°C/W