SGS Thomson Microelectronics ST619LBN, ST619LBDR, ST619LBD Datasheet

1/9May 2001

■ REGULATED 5V ±4% CHARGE PUMP

■ OUTPUT CURRENT GUARANTEED OVER

TEMPERATURE : 20mA (V

I

≥ 2V ),

30mA (V

I

≥ 3V )

■ NO INDUCTORS; VERY LOW EMI NOISE

■ USES SMALL, INEXPENSIVE CAPACITORS

■ LOGIC CONTROLLED 1µA MAX

SHUT-DOWN SUPPLY CURRENT

■ SHUT DOWN DISCONNECTS LOAD FROM

INPUT

■ AVAILABLE IN SO-8 AND DIP-8 PACKAGES

DESCRIPTION

The ST619LB is a step-up c harge pump DC-DC
converter which delivers a regulated 5V ±4%
output at 30mA and over temperature. The input
voltage range is 2V to 3.6V (two battery cells).
It requires only four external capacitor: two 0.22µF
flying capacitors, and 10µF capacitors at the input
and ou tput .

Low operating supply current (typ 200µA) make
the device ideal for small, portable and battery
powered applications. W hen shut down the load
is disconnected from the input and the supply
current is typically 0.02µA. The ST619LB is
available in SO-8 and DIP-8 packages.

ST619LB

SERIES

DC-DC CONVERTER REGULATED 5V CHARGE PUMP

SCHEMATIC DIAGRAM

DIP-8 SO-8

ST619LB SERIES

2/9

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 vo ltage is regulated to 5V,
±4% by a pulse skipping controller that turns on
the charge pump when the output voltage beg ins
to drop. To maintain the greatest efficiency the
internal charge pump of the device operates as a
voltage doubler when V

I

ranges from 3.0V to 3.6V

and as a voltage tripler when V

I

ranges from 2.0V
to 2.5V.
When V

I

ranges from 2.5 V to 3 .0V , t he S T6 19LB
switches between doubler and tripler mode on
alternating cycles, making a 2.5 x V

I

charge pump.
To further enhance the efficiency over the input
range, an internal comparator selects the higher of
V

I

or VO to run the ST619LB’s circuitry. With VI =

2V and I

O

= 20mA the typical eff iciency value is
80%.
In tripler mode (see block diagram), when the S1
switches close, the S2 switches open and

capacitors C1 and C2 charge up to V

I

. On the
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,
OUT is disconne cted from the IN and V

O

falls to
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 ther m al design of PCB on which the device is mounted.

Symbol Parameter² Value Unit

V

I

DC Input Voltage

-0.3 to 5.5 V

V

O

Output Voltage

-0.3 to 5.5 V

V

SHDN

Shutdown Input Voltage -0.3 to (VI + 0.3)

V

I

O

Output Current Continuous

120 mA

T

stg

Storage Temperature Range

-55 to +150 °C

T

op

Operating Junction Temperature Range

-40 to +85 °C

Symbol Parameter SO-8 DIP-8 Unit

R

thj-amb

Thermal Resistance Junction-ambient (*)

160 100 °C/W

ST619LB SERIES

3/9

CONNECTION DIAGRAM (top view)

ORDERING CODES

PIN DESCRIPTION

ELECTRICAL CHARACTERISTICS (V

I

=2 to 3.6V, C1 = C2 =0.22µF, C3 = C4 =10µF, TA = -40 to 85°C,

unless otherwise specified. Typical value are referred at T

A

= 25°C)

Note: Do not overload or short the Output to Ground. If the above conditions are not observed the device may be damaged.

TYPE DIP-8 SO-8 SO-8 (T&R)

ST619LB ST619LBN ST619LBD ST619LBDR

Pin N° Symbol Name and Function

1 C1+ Positive terminal for the first charge

pump capacitor
2 IN Input supply voltage
3 OUT 5V output voltage. V

O

=0V when in

shutdown mode.
4 C2+ Positive terminal for the second

charge pump capacitor
5 C2- Negative terminal for the second

charge pump capacitor
6 GND Ground
7 SHDN Active high C-MOS logic level

shutdown input. SHDN is connected

to GND for normal operation.
8 C1- Negative terminal for the first charge

pump capacitor

Symbol Parameter Test Conditions Min. Typ. Max. Unit

V

I

Input Voltage 2 3.6 V

V

O

Output Voltage VI = 2 to 3.6V IO =0 to 20mA

V

I

= 3 to 3.6V IO =0 to 30mA

4.8

4.8

5
5

5.2

5.2

V
V

V

RIPPLE

Output Voltage Ripple No load, Full Load 100 mV

I

i

No Load Supply Current VI = 2 to 3V No Load

V

I

= 3 to 3.6V No Load

20075300

150

µA
µA

I

SHDN

Shutdown Supply Current VI = 2 to 3.6V No Load

V

SHDN

= V

I

0.02 1 µA

ν Efficency V

I

= 3V IO =20mA

V

I

= 3V IO =30mA

V

I

= 2V IO =20mA

82
82
80

%
%
%

f

OSC

Switching Frequency Full Load 500 KHz

V

IH

SHDN Input Threshold 0.7V

I

V

V

IL

SHDN Input Threshold 0.4 V

I

IH

SHDN Input Current V

SHDN

= V

I

0.005 ± 1 µA