ST5R00
SERIES
MICROPOWER VFM STEP-UP DC/DC CONVERTER
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SOT23-5L
VERY LOW SUPPLY CURRENT
REGULATED OUTPUT VOLTAGE
WIDE RANGE OF OUTPUT VOLTAGE
AVAILABLE (2.5V, 2.8V, 3.0V, 3.3V, 5.0V)
OUTPUT VOLTAGE ACCURACY ±5%
OUTPUT CURRENT UP TO 100mA
LOW RIPPLE AND LOW NOISE
VERY LOW START-UP VOLTAGE
HIGH EFFICIENCY (V
OUT
= 5V TYP. 87%)
FEW EXTERNAL COMPONENTS
VERY SMALL PACKAGE: SOT23-5L
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DESCRIPTION
The ST5R00 is an high efficiency VFM Step-up
DC/DC converter for small, low input voltage or
battery powered systems with ultra low quiescent
supply current. The ST5Rxx accept a positive
input voltage from start-up voltage to V
OUT
and
convert it to a higher output voltage in the 2.5 to
5V range.
The ST5R00 combine ultra low quiescent supply
current and high efficiency to give maximum
battery life. The high switching frequency and the
internally limited peak inductor current, permits
the use of small, low cost inductors. Only three
external components are needed: an inductor a
diode and an output capacitor.
The ST5R00 is suitable to be used in a battery
powered equipment where low noise, low ripple
and ultra low supply current are required. The
ST5R00 is available in very small packages:
SOT23-5L.
Typical applications are pagers, cameras & video
camera, cellular telephones, wireless telephones,
palmtop computer, battery backup supplies,
battery powered equipment.
Figure 1: Schematic Diagram
June 2005
Rev. 6
1/15
ST5R00 SERIES
Table 1: Absolute Maximum Ratings
Symbol
V
OUT
V
IN
V
LX
I
LX
P
TOT
T
STG
T
OP
Output Voltage
Input Voltage
LX Pin Voltage
LX Pin Output Current
Power Dissipation at 25°C
Storage Temperature Range
Operating Junction Temperature Range
Parameter
Value
5.5
5.5
5.5
Internally limited
170 (*)
-55 to 125
-25 to 85
mW
°C
°C
Unit
V
V
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Table 2: Thermal Data
Symbol
R
thj-case
Parameter
SOT23-5L
63
Thermal Resistance Junction-case
(*) Reduced by 1.7 mW for increasing in T
A
of 1°C over 25°C
Absolute Maximum Ratings are those values beyond which damage to the device may occur. Functional operation under these condition is
not implied.
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Unit
°C/W
Figure 2: Connection Diagram
(top view)
Table 3: Order Codes
SOT23-5L
OUTPUT VOLTAGES
2.5 V
2.8 V
3.0 V
3.3 V
5.0 V
ST5R25MTR
ST5R28MTR
ST5R30MTR
ST5R33MTR
ST5R50MTR
2/15
ST5R00 SERIES
OPERATION
The ST5Rxx architecture is built around a VFM CONTROL logic core: switching frequency is set through
a built in oscillator: T
ON
time is fixed (Typ. 5ms) while T
OFF
time is determined by the error amplifier
output, a logic signal coming from the comparison made by the Error Amplifier Stage between the signal
coming from the output voltage divider network and the internal Band-Gap voltage reference (V
ref
). T
OFF
reaches a minimum (Typ. 1.7ms) when heavy load conditions are met (Clock frequency 150KHz). An over
current conditions, through the internal power switch, causes a voltage drop V
LX
=R
DSON
xI
SW
and the V
LX
limiter block forces the internal switch to be off, so narrowing T
ON
time and limiting internal power
dissipation. In this case the switching frequency may be higher than the 150KHz set by the internal clock
generator.
VFM control ensures very low quiescent current and high conversion efficiency even with very light loads.
Since the Output Voltage pin is also used as the device Supply Voltage, the versions with higher output
voltage present an higher internal supply voltage that results in lower power switch R
DSON
, slightly greater
output power and higher efficiency. Moreover, bootstrapping allows the input voltage to sag to 0.6V (at
I
OUT
=1mA) once the system is started.
If the input voltage exceeds the output voltage, the output will follow the input, however, the input or output
voltage must not be forced above 5.5V.
Figure 3: Typical Application Circuit
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(*) See application info.
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Figure 4:
Typical Application Efficiency
3/15
ST5R00 SERIES
Figure 5: Typical Demoboard
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Note: drawing not in scale.
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Table 4: Electrical Characteristics For ST5R25
(V
IN
= 1.5V, I
OUT
= 10mA, T
A
= 25°C, unless otherwise specified. For external components value, unless
otherwise notes, refer to the typical operating circuit.)
Symbol
V
OUT
Parameter
Test Conditions
Min.
Typ.
2.5
0.8
16
Max.
1.2
Unit
V
V
V
Output Voltage
2.375
0.6
2.625
V
START-UP
Start-up Voltage (V
IN
-V
F
) (1)
V
HOLD
Hold-on Voltage
Supply Current
I
SUPPLY
I
OUT
= 1mA, V
IN
= rising from 0 to 2V
I
OUT
= 1mA, V
IN
= falling from 2 to 0V
To be measured at V
IN
, no load
I
LX
= 150mA
V
LX
= 4V, forced V
OUT
= 3V
µA
µA
%
R
LX(DSON)
Internal Switch R
DSON
I
LX(leak)
Internal Leakage Current
f
OSC
D
ty
½
Oscillator Duty Cycle
Efficiency
850
mΩ
0.5
Maximum oscillator Frequency
150
77
82
KHz
%
to be measure on LX pin
I
OUT
= 50mA
(1): The minimum input voltage for the IC start-up is strictly a function of the V
F
catch diode.
Table 5: Electrical Characteristics For ST5R28
(V
IN
= 1.7V, I
OUT
= 10mA, T
A
= 25°C, unless otherwise specified. For external components value, unless
otherwise notes, refer to the typical operating circuit.)
Symbol
V
OUT
Parameter
Test Conditions
Min.
2.66
0.6
Typ.
2.8
0.8
16
Max.
2.94
1.2
Unit
V
V
V
Output Voltage
V
START-UP
Start-up Voltage (V
IN
-V
F
) (1)
V
HOLD
Hold-on Voltage
Supply Current
I
SUPPLY
I
OUT
= 1mA, V
IN
= rising from 0 to 2V
I
OUT
= 1mA, V
IN
= falling from 2 to 0V
To be measured at V
IN
, no load
I
LX
= 150mA
V
LX
= 4V, forced V
OUT
= 3.3V
µA
µA
%
%
R
LX(DSON)
Internal Switch R
DSON
I
LX(leak)
Internal Leakage Current
f
OSC
D
ty
½
Oscillator Duty Cycle
Efficiency
850
mΩ
0.5
Maximum oscillator Frequency
to be measure on LX pin
I
OUT
= 50mA
150
77
82
KHz
(1): The minimum input voltage for the IC start-up is strictly a function of the V
F
catch diode.
4/15
ST5R00 SERIES
Table 6: Electrical Characteristics For ST5R30
(V
IN
= 1.8V, I
OUT
= 10mA, T
A
= 25°C, unless otherwise specified. For external components value, unless
otherwise notes, refer to the typical operating circuit.)
Symbol
V
OUT
V
HOLD
I
SUPPLY
Parameter
Output Voltage
I
OUT
= 1mA, V
IN
= rising from 0 to 2V
I
OUT
= 1mA, V
IN
= falling from 2 to 0V
To be measured at V
IN
, no load
I
LX
= 150mA
V
LX
= 4V, forced V
OUT
= 3.5V
150
to be measure on LX pin
I
OUT
= 50mA
77
82
0.6
17
850
0.5
Hold-on Voltage
Supply Current
Test Conditions
Min.
2.85
Typ.
3
0.8
Max.
3.15
1.2
Unit
V
V
V
µA
mΩ
µA
%
KHz
%
V
START-UP
Start-up Voltage (V
IN
-V
F
) (1)
R
LX(DSON)
Internal Switch R
DSON
I
LX(leak)
Internal Leakage Current
f
OSC
D
ty
½
Maximum oscillator Frequency
Oscillator Duty Cycle
Efficiency
(1): The minimum input voltage for the IC start-up is strictly a function of the V
F
catch diode.
Table 7: Electrical Characteristics For ST5R33
(V
IN
= 2V, I
OUT
= 10mA, T
A
= 25°C, unless otherwise specified. For external components value, unless
otherwise notes, refer to the typical operating circuit.)
Symbol
V
OUT
Parameter
Test Conditions
Min.
Typ.
3.3
0.8
17
Max.
1.2
Unit
V
V
V
V
START-UP
Start-up Voltage (V
IN
-V
F
) (1)
V
HOLD
Hold-on Voltage
Supply Current
I
SUPPLY
R
LX(DSON)
Internal Switch R
DSON
I
LX(leak)
Internal Leakage Current
f
OSC
D
ty
½
Oscillator Duty Cycle
Efficiency
(1): The minimum input voltage for the IC start-up is strictly a function of the V
F
catch diode.
Table 8: Electrical Characteristics For ST5R50
(V
IN
= 3V, I
OUT
= 10mA, T
A
= 25°C, unless otherwise specified. For external components value, unless
otherwise notes, refer to the typical operating circuit.)
Symbol
V
OUT
Parameter
Test Conditions
Min.
4.75
0.6
Typ.
5.0
0.8
18
700
0.5
160
to be measure on LX pin
I
OUT
= 50mA
77
87
Max.
5.25
1.2
Unit
V
V
V
b
O
V
START-UP
Start-up Voltage (V
IN
-V
F
) (1)
V
HOLD
Hold-on Voltage
Supply Current
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SUPPLY
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Output Voltage
3.135
0.6
3.465
I
OUT
= 1mA, V
IN
= rising from 0 to 2V
I
OUT
= 1mA, V
IN
= falling from 2 to 0V
To be measured at V
IN
, no load
I
LX
= 150mA
V
LX
= 4V, forced V
OUT
= 3.8V
850
0.5
Maximum oscillator Frequency
150
77
83
to be measure on LX pin
I
OUT
= 50mA
Output Voltage
I
OUT
= 1mA, V
IN
= rising from 0 to 2V
I
OUT
= 1mA, V
IN
= falling from 2 to 0V
To be measured at V
IN
, no load
I
LX
= 150mA
V
LX
= 4V, forced V
OUT
= 3.8V
Maximum oscillator Frequency
Oscillator Duty Cycle
Efficiency
s)
t(
µA
µA
%
mΩ
KHz
%
µA
mΩ
µA
KHz
%
%
R
LX(DSON)
Internal Switch R
DSON
I
LX(leak)
Internal Leakage Current
f
OSC
D
ty
½
(1): The minimum input voltage for the IC start-up is strictly a function of the V
F
catch diode.
5/15
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