ETC ST619LBN

ST619LB
SERIES
DC-DC CONVERTER REGULATED 5V CHARGE PUMP
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REGULATED 5V ±4% CHARGE PUMP
OUTPUT CURRENT GUARANTEED OVER
TEMPERATURE : 20mA (VI ≥ 2V ),
30mA (VI ≥ 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 charge 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 output.
DIP-8
SO-8
Low operating supply current (typ 200µA) make
the device ideal for small, portable and battery
powered applications. When 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.
SCHEMATIC DIAGRAM
May 2001
1/9
ST619LB SERIES
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
voltage doubler when VI ranges from 3.0V to 3.6V
and as a voltage tripler when VI ranges from 2.0V
to 2.5V.
When VI ranges from 2.5V to 3.0V , the ST619LB
switches between doubler and tripler mode on
alternating cycles, making a 2.5 x VI charge pump.
To further enhance the efficiency over the input
range, an internal comparator selects the higher of
VI or VO to run the ST619LB’s circuitry. With VI =
2V and IO = 20mA the typical efficiency 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 VI. 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 disconnected from the IN and VO falls to
0V. The SHDN pin is connected to ground for
normal operation. SHDN is a CMOS compatible
input.
ABSOLUTE MAXIMUM RATINGS
Symbol
Parameter
VI
DC Input Voltage
VO
Output Voltage
VSHDN
IO
Shutdown Input Voltage
Output Current Continuous
Value
Unit
-0.3 to 5.5
V
-0.3 to 5.5
V
-0.3 to (VI + 0.3)
120
V
mA
Tstg
Storage Temperature Range
-55 to +150
°C
Top
Operating Junction Temperature Range
-40 to +85
°C
Absolute Maximum Ratings are those values beyond which damage to the device may occur. Functional operation under these condition is
not implied.
THERMAL DATA
Symbol
Rthj-amb
Parameter
Thermal Resistance Junction-ambient (*)
SO-8
DIP-8
Unit
160
100
°C/W
(*) This value depends from thermal design of PCB on which the device is mounted.
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ST619LB SERIES
CONNECTION DIAGRAM (top view)
PIN DESCRIPTION
Pin N° Symbol
1
C1+
2
3
IN
OUT
4
C2+
5
C2-
6
7
GND
SHDN
8
C1-
ORDERING CODES
TYPE
DIP-8
SO-8
SO-8 (T&R)
ST619LB
ST619LBN
ST619LBD
ST619LBDR
Name and Function
Positive terminal for the first charge
pump capacitor
Input supply voltage
5V output voltage. VO=0V when in
shutdown mode.
Positive terminal for the second
charge pump capacitor
Negative terminal for the second
charge pump capacitor
Ground
Active high C-MOS logic level
shutdown input. SHDN is connected
to GND for normal operation.
Negative terminal for the first charge
pump capacitor
ELECTRICAL CHARACTERISTICS (VI=2 to 3.6V, C1 = C2 =0.22µF, C3 = C4 =10µF, TA = -40 to 85°C,
unless otherwise specified. Typical value are referred at TA = 25°C)
Symbol
Parameter
VI
Input Voltage
VO
Output Voltage
VRIPPLE Output Voltage Ripple
Test Conditions
Min.
Typ.
Max.
3.6
V
5
5
5.2
5.2
V
V
2
V I = 2 to 3.6V
V I = 3 to 3.6V
IO =0 to 20mA
IO =0 to 30mA
4.8
4.8
No load, Full Load
100
Unit
mV
No Load Supply Current
V I = 2 to 3V
V I = 3 to 3.6V
No Load
No Load
200
75
300
150
µA
µA
Shutdown Supply Current
V I = 2 to 3.6V
V SHDN = VI
No Load
0.02
1
µA
Efficency
V I = 3V
V I = 3V
V I = 2V
fOSC
Switching Frequency
Full Load
VIH
SHDN Input Threshold
VIL
SHDN Input Threshold
IIH
SHDN Input Current
Ii
ISHDN
ν
IO =20mA
IO =30mA
IO =20mA
82
82
80
%
%
%
500
KHz
0.7V I
V SHDN = VI
V
0.005
0.4
V
±1
µA
Note: Do not overload or short the Output to Ground. If the above conditions are not observed the device may be damaged.
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ST619LB SERIES
TYPICAL PERFORMANCE CHARACTERISTICS (unless otherwise specified TA = 25°C)
Figure 1 : No Load Supply Current vs Input
Voltage
Figure 4 : Output Voltage vs Output Current
Figure 2 : Shutdown Supply Current vs Input
Voltage
Figure 5 : Efficency vs Output Current
Figure 3 : Maximum Output Current vs Input
Voltage
Figure 6 : Efficency vs Input Voltage
4/9
ST619LB SERIES
Figure 7 : Output Voltage vs Input Voltage
Figure 10 : Line Transient Response
RL=250Ω
Figure 8 : Start-up
Figure 11 : Load Transient Response
VI=3V, IO=0 to 25mA
Figure 9 : Output Voltage vs Temperature
5/9
ST619LB SERIES
APPLICATION INFORMATION
Charge pump capacitors C1 and C2
The values of charge pump capacitors C1 and C2
are critical to ensure adequate output current and
avoid excessive peak currents. It is suggested to
use values in the range of 0.22µF to 1.0µF and
avoid the use of higher values of CO capacitors, in
order to obtain best performance. Ceramic or
tantalum capacitors are recommended.
Input and output capacitors C3 and C4
The type of input capacitor (C3) and output filter
capacitor (C4) used is not critical, but it does affect
performance. Tantalums, ceramics or aluminium
electrolytic are suggested. For lowest ripple, use
large, low effective series resistance (ESR)
ceramic tantalum capacitors. If the input supply
TYPICAL APPLICATION CIRCUIT
TYPICAL APPLICATION DEMOBOARD
6/9
source impedance is very low, C3 can be omitted.
The typical application circuit shows the
component values for proper operation using
minimal board space. The input bypass capacitor
(C3) and output filter capacitor (C4) should be at
least 10µF. Many capacitors exhibit 40% to 50%
variation over temperature. Compensate for
capacitor temperature coefficient by selecting a
large nominal value to ensure proper operation
over temperature.
Layout Consideration
In the below figure, the typical application
demoboard of ST619LB is reported. A good layout
ensures stability and helps maintain the output
voltage under heavy loads. For best performance,
use very short connections to the capacitors.