Micropower 1 A synchronous step-up DC-DC converter
Features
■ Output voltage adjustable from 6 V to 12 V
■ Output voltage accuracy: ± 2%
■ Output current up to 1 A
■ Low ripple voltage: 5 mV (typ.)
■ Synchronous rectification
■ High 90% efficiency: V
■ Few external components
■ Thermal shutdown protection
■ Very small DFN8 (4 x 4 mm) package
Description
The ST8R00 is a synchronous PWM step-up DCDC converter. The device is able to provide an
output voltage in the range of 6 to 12 V with an
input voltage from 4 to 6 V. The high switching
frequency (1.7 MHz) permits the use of tiny
surface-mount components. In addition to the
resistor divider to set the output voltage value,
only an inductor and two capacitors are required.
Moreover, a low output ripple is guaranteed by the
current mode PWM topology and by the use of
low ESR SMD ceramic capacitors. The device is
available in a very small DFN8 (4 x 4 mm)
package.
= 9 V (typ.)
O
ST8R00
DFN8 4 x 4 mm
Table 1. Device summary
Part number Order code Output voltage
ST8R00 ST8R00WPUR ADJ
February 2012 Doc ID 13449 Rev 2 1/18
www.st.com
18
Contents ST8R00
Contents
1 Block diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
2 Pin configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
3 Typical application circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
4 Maximum ratings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
5 Electrical characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
6 Typical characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
7 Package mechanical data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
8 Revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
2/18 Doc ID 13449 Rev 2
ST8R00 Block diagram
1 Block diagram
Figure 1. Schematic diagram
LX
LX
Thermal
Thermal
OUT
OUT
INH
INH
IN
IN
Inhibit
Inhibit
V
V
REF
REF
PGND
PGND
PWM Control
PWM Control
FB
FB
GNDPGND
GNDPGND
Doc ID 13449 Rev 2 3/18
Pin configuration ST8R00
2 Pin configuration
Figure 2. Pin connections (top view)
Table 2. Pin description
Pin n° Symbol Name and function
1 LX Switching output
2 PGND Power ground
3 GND Analog ground
4 IN Power input for analog circuit
5 FB Feedback
Inhibit. Connecting the pin to a voltage higher than 2 V = device ON.
6INH
7 HV Trimming (floating or connected to GND)
8 OUT Output voltage
EXP pad GND Exposed pad. Must be connected to GND
Connecting the pin to a voltage lower than 0.8 V = device OFF,
resulting in no current flow to the load
4/18 Doc ID 13449 Rev 2
ST8R00 Typical application circuit
3 Typical application circuit
Figure 3. Application circuit
V
V
I
I
CI=10µF
CI=10µF
L=4.7µH
L=4.7µH
IN LX
IN LX
OUT
OUT
INH
INH
ST8R00
ST8R00
GND PGND
GND PGND
FB
FB
R1
R1
R2
R2
V
V
O
O
CO=10µF
CO=10µF
Doc ID 13449 Rev 2 5/18
Maximum ratings ST8R00
4 Maximum ratings
Table 3. Absolute maximum ratings
Symbol Parameter Value Unit
Output voltage 16 V
Input voltage 6 V
Inhibit voltage 6 V
LX pin voltage 16 V
LX pin output current Internally limited
Storage temperature range -50 to 150 °C
Operating junction temperature range -25 to 125 °C
T
V
V
V
V
I
STG
T
O
I
INH
LX
LX
OP
Table 4. Thermal Data
Symbol Parameter Value Unit
R
R
thJC
thJA
Thermal resistance junction-case 10 °C/W
Thermal resistance junction-ambient 50 °C/W
Table 5. ESD Performance
Symbol Parameter Test conditions Value Unit
ESD ESD protection voltage HBM 4 KV
ESD ESD protection voltage MM 500 V
6/18 Doc ID 13449 Rev 2
ST8R00 Electrical characteristics
5 Electrical characteristics
VI = 5 V, V
= 2 V, IO = 100 mA, TJ = - 25 °C to 125 °C, CI = CO = 10 µF(X7R), L = 4.7 µH
INH
unless otherwise specified.
Table 6. Electrical characteristics
Symbol Parameter Test conditions Min. Typ. Max. Unit
V
O
V
START-UP
V
I
V
FB
V
FB_OFF
I
FB
I
SUPPLY
R
DSON_N
R
DSON_P
I
LX(leak)
I
LX(LIM)
f
OSC
D
TY
Eff Efficiency
Output voltage
(1)
612V
Start-up voltage IO = 400mA, VI rising 3 3.5 V
Input voltage range 4 6 V
Feedback voltage IO = 50mA 1.195 1.22 1.245 V
Feedback voltage IO = 0, V
Feedback current V
Supply current
Internal N channel R
Internal P channel R
DSON
DSON
Internal leakage current V
LX current limitation V
= 0, V
FB
To be measured at V
load
ILX = 400mA 300
ILX = 400mA 300
= 4V, V
LX
= 4V 3 A
LX
= 0 0 V
INH
= 2V 600 nA
INH
, VO = 7V, no
FB
= 2V, V
I
= 0 0.5 µA
INH
10 mA
Oscillator frequency To be measured on LX pin 0.8 1.2 1.4 MHz
Max. oscillator duty cycle To be measured on LX pin 90 %
I
= 50mA, VO = 7V 85
O
mΩ
%IO = 500mA, VO = 9V 90
I
= 1A, VO = 9V 90
O
V
INH_H
V
INH_L
I
INH
T
SHDN
T
HYS
ΔV
O
ΔVO/ΔIOLoad transient response
Inhibit threshold high 2
Inhibit threshold low VI = 4 to 6V, IO = 50mA 0.8
Inhibit pin current V
Thermal shut down
Thermal shut down hysteresis
(2)
(2)
/ΔVILine transient response VI from 4 to 5.5V, IO= 500mA
= VI = 5V 2 µA
INH
130 150 °C
= 5V, IO from 10mA to 500mA,
V
I
(2)
= 7V
V
O
(2)
-5 5 %V
-5 5 %V
15 °C
ΔVO/ΔVIStart-up transient VI from 0 to 5V, IO = 500mA -10 10 %V
T
START
1. For VO higher than 9 V the maximum output current capability is reduced according to LX current limitation
2. Guaranteed by design
Start-up time V
from 0 to 5V, IO = 100mA 500 µs
INH
Doc ID 13449 Rev 2 7/18
V
O
O
O
Typical characteristics ST8R00
6 Typical characteristics
L = 4.7 µH, CI = CO = 10 µF.
Figure 4. Voltage feedback vs. temperature Figure 5. Feedback current vs. temperature
700
1.3
1.3
1.28
1.28
1.26
1.26
1.24
1.24
1.22
1.22
[mV]
[mV]
1.2
1.2
FB
FB
1.18
1.18
V
V
1.16
1.16
1.14
1.14
1.12
1.12
1.1
1.1
-75 -50 -25 0 25 50 75 100 125 150 175
-75 -50 -25 0 25 50 75 100 125 150 175
T [°C]
T [°C]
VI=V
VI=V
=5V, IO=50mA
=5V, IO=50mA
INH
INH
700
600
600
500
500
400
400
[nA]
[nA]
300
300
FB
FB
I
I
200
200
100
100
0
0
-100
-100
-75 -50 -25 0 25 50 75 100 125 150 175
-75 -50 -25 0 25 50 75 100 125 150 175
VI=5V, V
VI=5V, V
T [°C]
T [°C]
=2V, No Inductor, No Bridge
=2V, No Inductor, No Bridge
INH
INH
Figure 6. Supply current vs. temperature
(V
= V
VI=V
VI=V
I
=5V, No Load
=5V, No Load
INH
INH
20
20
18
18
16
16
14
14
12
12
[mA]
[mA]
10
10
8
8
SUPPLY
SUPPLY
I
I
6
6
4
4
2
2
0
0
-75 -50 -25 0 25 50 75 100 125 150 175
-75 -50 -25 0 25 50 75 100 125 150 175
INH
= 5 V)
T [°C]
T [°C]
@VO=7V
@VO=7V
Figure 8. Supply current vs. temperature
(V
= 2 V)
800
750
700
650
[ µA]
600
550
SUPPLY
I
500
450
400
-75 -50 -25 0 25 50 75 100 125 150 175
FB
VI = V
= 5 V, V
INH
No resistors bridge and inductor directly to V
= 2 V
FB
T [°C]
I
Figure 7. Supply current vs. temperature
(V
= 2 V)
INH
20
20
15
15
[mA]
[mA]
10
10
SUPPLY
SUPPLY
I
I
5
5
0
0
-75 -50 -25 0 25 50 75 100 125 150 175
-75 -50 -25 0 25 50 75 100 125 150 175
VI=5,V
VI=5,V
T [°C]
T [°C]
=2V,No Load, VO@ 7V
=2V,No Load, VO@ 7V
INH
INH
Figure 9. LX current limitation vs.
temperature
4
4
3.5
3.5
3
3
2.5
2.5
[A]
[A]
2
2
LX
LX
I
I
1.5
1.5
1
1
0.5
0.5
0
0
-75 -50 -25 0 25 50 75 100 125 150 175
-75 -50 -25 0 25 50 75 100 125 150 175
T [°C]
T [°C]
VIN=V
VIN=V
=5V, @VO<10%
=5V, @VO<10%
INH
INH
8/18 Doc ID 13449 Rev 2
ST8R00 Typical characteristics
Figure 10. Inhibit voltage vs. temperature
3
3
2.5
2.5
2
2
[V]
[V]
1.5
1.5
INH
INH
V
V
1
1
0.5
0.5
0
0
Figure 12. Line regulation vs. temperature Figure 13. Load regulation vs. temperature
1
1
0.8
0.8
0.6
0.6
]
]
I
I
0.4
0.4
/ΔV
/ΔV
0.2
0.2
O
O
0
0
-0.2
-0.2
-0.4
-0.4
-0.6
-0.6
LINE [%V
LINE [%V
-0.8
-0.8
-1
-1
(V
= 4 V)
I
VI=4V, V
from 0 to 2V, IO=50mA
VI=4V, V
from 0 to 2V, IO=50mA
INH
INH
-75 -50 -25 0 25 50 75 100 125 150 175
-75 -50 -25 0 25 50 75 100 125 150 175
T [°C]
T [°C]
VI= from 4V to 6V, IO=1A
VI= from 4V to 6V, IO=1A
@9.5V
@9.5V
V
V
O
O
-75 -50 -25 0 25 50 75 100 125 150 175
-75 -50 -25 0 25 50 75 100 125 150 175
T [°C]
T [°C]
ON
ON
OFF
OFF
Figure 11. Inhibit voltage vs. temperature
(VI = 6 V)
3
3
VI=6V, V
from 0 to 2V, IO=50mA
VI=6V, V
from 0 to 2V, IO=50mA
INH
2.5
2.5
2
2
[V]
[V]
1.5
1.5
INH
INH
V
V
1
1
0.5
0.5
0
0
-75 -50 -25 0 25 50 75 100 125 150 175
-75 -50 -25 0 25 50 75 100 125 150 175
1
1
0.8
0.8
0.6
0.6
]
]
O
O
0.4
0.4
/ΔI
/ΔI
0.2
0.2
O
O
0
0
-0.2
-0.2
-0.4
-0.4
-0.6
-0.6
LOAD [%V
LOAD [%V
-0.8
-0.8
-1
-1
-75 -50 -25 0 25 50 75 100 125 150 175
-75 -50 -25 0 25 50 75 100 125 150 175
INH
VI=5V, IO from 100mA to 1A
VI=5V, IO from 100mA to 1A
V
V
T [°C]
T [°C]
@9.5V
@9.5V
O
O
T [°C]
T [°C]
ON
ON
OFF
OFF
Figure 14. Oscillator frequency vs.
1.7
1.7
1.5
1.5
1.3
1.3
1.1
1.1
0.9
0.9
PWM freq.[MHz]
PWM freq.[MHz]
0.7
0.7
0.5
0.5
temperature
VI=V
=5V, No Inductor, No Load
VI=V
=5V, No Inductor, No Load
INH
INH
-75 -50 -25 0 25 50 75 100 125 150 175
-75 -50 -25 0 25 50 75 100 125 150 175
T [°C]
T [°C]
Doc ID 13449 Rev 2 9/18
Figure 15. Max oscillator duty cycle vs.
temperature
100
100
VI=V
=5V, VFB=GND, No Inductor
VI=V
=5V, VFB=GND, No Inductor
INH
97.5
97.5
92.5
92.5
87.5
87.5
Dutycycle MAX [%]
Dutycycle MAX [%]
82.5
82.5
INH
95
95
90
90
85
85
80
80
-75 -50 -25 0 25 50 75 100 125 150 175
-75 -50 -25 0 25 50 75 100 125 150 175
T [°C]
T [°C]
Typical characteristics ST8R00
Figure 16. Internal leakage current vs.
0.1
0.1
0.09
0.09
0.08
0.08
0.07
0.07
0.06
0.06
0.05
0.05
(leak)[mA]
(leak)[mA]
0.04
0.04
LX
LX
0.03
0.03
I
I
0.02
0.02
0.01
0.01
0
0
temperature (V
VI=V
=5V, VFB=2V, VLX=4V, No Inductor
VI=V
=5V, VFB=2V, VLX=4V, No Inductor
INH
INH
-75 -50 -25 0 25 50 75 100 125 150 175
-75 -50 -25 0 25 50 75 100 125 150 175
T [°C]
T [°C]
= V
I
INH
= 5 V)
Figure 18. NMOS switch on resistance vs.
500
500
400
400
300
300
[mΩ]
[mΩ]
200
200
DSON-N
DSON-N
R
R
100
100
0
0
-75 -50 -25 0 25 50 75 100 125 150 175
-75 -50 -25 0 25 50 75 100 125 150 175
temperature
VI=5V
VI=5V
T [°C]
T [°C]
Figure 17. Internal leakage current vs.
temperature (VI = 5 V)
0.6
0.6
0.5
0.5
0.4
0.4
0.3
(leak)[uA]
(leak)[uA]
I
I
LX
LX
-0.1
-0.1
0.3
0.2
0.2
0.1
0.1
VI=5 , V
=GND, VFB=2V, VLX=4V, No Inductor
VI=5 , V
=GND, VFB=2V, VLX=4V, No Inductor
INH
INH
0
0
-75 -50 -25 0 25 50 75 100 125 150 175
-75 -50 -25 0 25 50 75 100 125 150 175
T [°C]
T [°C]
Figure 19. PMOS switch on resistance vs.
temperature
500
500
VI=5V
VI=5V
400
400
]
]
Ω
Ω
300
300
[m
[m
200
200
DSON-P
DSON-P
R
R
100
100
0
0
-75 -50 -25 0 25 50 75 100 125 150 175
-75 -50 -25 0 25 50 75 100 125 150 175
T [°C]
T [°C]
Figure 20. Efficiency vs. output current
1.00
1.00
0.90
0.90
0.80
0.80
0.70
0.70
0.60
0.60
0.50
0.50
0.40
0.40
Efficiency [%]
Efficiency [%]
0.30
0.30
0.20
0.20
0.10
0.10
0.00
0.00
(L = 10 µH)
@7V
@7V
V
V
O
O
VI= V
=5V, L=10µH, IO= from 0A to 1A
VI= V
=5V, L=10µH, IO= from 0A to 1A
INH
INH
0 100 200 300 400 500 600 700 800 900 1000
0 100 200 300 400 500 600 700 800 900 1000
I
I
[mA]
[mA]
O
O
Figure 21. Efficiency vs. output current
1.00
1.00
0.90
0.90
0.80
0.80
0.70
0.70
0.60
0.60
0.50
0.50
0.40
0.40
Efficiency [%]
Efficiency [%]
0.30
0.30
0.20
0.20
0.10
0.10
0.00
0.00
10/18 Doc ID 13449 Rev 2
@7V
@7V
V
V
O
O
VI= V
=5V, IO=from 0A to 1A
VI= V
=5V, IO=from 0A to 1A
INH
INH
0 100 200 300 400 500 600 700 800 900 1000
0 100 200 300 400 500 600 700 800 900 1000
[mA]
[mA]
I
I
O
O
ST8R00 Typical characteristics
Figure 22. Output voltage vs. input voltage Figure 23. Maximum output current vs. output
12.00
12.00
125°C
10.00
10.00
8.00
8.00
[V]
[V]
6.00
6.00
O
O
V
V
4.00
4.00
2.00
2.00
0.00
0.00
Figure 24. Inductor current Figure 25. Load transient
125°C
25°C
25°C
0°C
0°C
-25°C
-25°C
V
VI=V
from 0 to 6V, IO=400mA
from 0 to 6V, IO=400mA
INH
I=VINH
0123456
0123456
VI[V]
VI[V]
V
LX
1.1
1.1
1
1
0.9
0.9
0.8
0.8
[A]
[A]
O
O
0.7
0.7
I
I
0.6
0.6
0.5
0.5
0.4
0.4
voltage
P
P
c
c
o
o
s
s
t
t
=
=
6
6
W
W
OPERATIVE ZONE
OPERATIVE ZONE
5.5 6.5 7.5 8.5 9.5 10.5 11.5 12.5
5.5 6.5 7.5 8.5 9.5 10.5 11.5 12.5
VO[V]
VO[V]
V
VI=V
I=VINH
INH
P
P
=5V
=5V
MAX
MAX
=6W
=6W
V
O
I
LX
VI=5V,V
Figure 26. Line transient Figure 27. INH transient
VI=V
= 2V, L=4.7µH, CI=CO=10µF, No Load, T=25°C
INH
from 4V to 5.5V, IO=500mA, 20µs
INH
VI=V
=5V, IO=from 10mA to 500mA
INH
V
I
V
O
VI=6, V
from 0V to 2V, IO=1A
INH
I
O
V
INH
V
O
I
O
Doc ID 13449 Rev 2 11/18
Typical characteristics ST8R00
Figure 28. Inrush current
VI=4.5, VO=7V, V
from 0V to 3V, IO=0, L=10µH
INH
12/18 Doc ID 13449 Rev 2
ST8R00 Package mechanical data
7 Package mechanical data
In order to meet environmental requirements, ST offers these devices in different grades of
ECOPACK
specifications, grade definitions and product status are available at:
ECOPACK
®
packages, depending on their level of environmental compliance. ECOPACK®
®
is an ST trademark.
www.st.com
.
Doc ID 13449 Rev 2 13/18
Package mechanical data ST8R00
DFN8 (4x4) Mechanical Data
mm. inch.
Dim.
Min. Typ. Max. Min. Typ. Max.
A0.800.901.000.0310.0350.039
A1 0 0.02 0.05 0 0.001 0.002
A3 0.20 0.008
b 0.23 0.300.38 0.009 0.012 0.015
D 3.90 4.00 4.10 0.154 0.157 0.161
D2 2.82 3.00 3.23 0.111 0.118 0.127
E 3.90 4.00 4.10 0.154 0.157 0.161
E2 2.05 2.20 2.30 0.0810.0870.091
e0.800.031
L 0.40 0.50 0.60 0.016 0.020 0.024
14/18 Doc ID 13449 Rev 2
7869653B
ST8R00 Package mechanical data
Figure 29. DFN8 (4 x 4) footprint recommended data
Doc ID 13449 Rev 2 15/18
Package mechanical data ST8R00
Tape & Reel QFNxx/DFNxx (4x4) Mechanical Data
mm. inch.
Dim.
Min. Typ. Max. Min. Typ. Max.
A 330 12.992
C 12.8 13.2 0.504 0.519
D 20.2 0.795
N 99 101 3.898 3.976
T 14.4 0.567
Ao 4.35 0.171
Bo 4.35 0.171
Ko 1.1 0.043
Po 4 0.157
P 8 0.315
16/18 Doc ID 13449 Rev 2
ST8R00 Revision history
8 Revision history
Table 7. Document revision history
Date Revision Changes
24-May-2007 1 Initial release.
01-Feb-2012 2
Modified:
Removed: Table 6, Figures 24, 25 and 26.
Figure 8 on page 8
.
Doc ID 13449 Rev 2 17/18
ST8R00
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18/18 Doc ID 13449 Rev 2
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