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ST1S12GR

P1-P3P4-P6P7-P9P10-P12P13-P15P16-P18P19-P20
Application notes ST1S12XX, ST1S12XX12, ST1S12XX18
10/20 Doc ID 14314 Rev 5
6 Application notes
The ST1S12 is an adjustable current mode PWM step-down DC-DC converter with internal
0.7 A power switch, packaged in TSOT23-5L. This device is a complete 0.7 A switching
regulator, with its internal compensation eliminating the need for additional components.
Because the ST1S12 an adjustable regulator, the output voltage is determined by an
external resistor divider. The desired value is derived by the following equation:
Equation 1
V
O
= V
FB
[1 + R
1
/ R
2
]
For the device to function only a few component are required: an inductor, two capacitors
and the resistor divider. The inductor selected must be capable of non saturation at peak
current level. Moreover, its value can be selected taking into account that a large inductor
value increases efficiency at low output current and reduces output voltage ripple, while a
smaller inductor can be used when it is important to reduce package size and the total cost
of the application. Finally, the ST1S12 has been designed to work properly with X5R or X7R
SMD ceramic capacitors both at the input and at the output. These types of capacitors, due
to their very low series resistance (ESR), minimize the output voltage ripple. Other low ESR
capacitors can be used according to the need of the application without compromising the
correct functioning of the device.
ST1S12XX, ST1S12XX12, ST1S12XX18 Typical performance characteristics
Doc ID 14314 Rev 5 11/20
7 Typical performance characteristics
Unless otherwise specified, refer to the typical application circuit under the following
conditions: C
IN
= 4.7 µF, C
OUT
= 10 µF, L = 2.2 µH
Figure 4. Voltage feedback vs. temperature Figure 5. Drop vs. temperature
Figure 6. Oscillator frequency vs.
temperature
Figure 7. Efficiency vs. output current
Figure 8. Efficiency vs. output current Figure 9. Efficiency vs. temperature
550
570
590
610
630
650
-75 -50 -25 0 25 50 75 100 125 150 175
T [°C]
V
FB
[mV]
V
IN
=V
EN
=3.6V, I
OUT
=10mA, V
OUT
=1.8V
550
570
590
610
630
650
-75 -50 -25 0 25 50 75 100 125 150 175
T [°C]
V
FB
[mV]
V
IN
=V
EN
=3.6V, I
OUT
=10mA, V
OUT
=1.8V
0
0.1
0.2
0.3
0.4
0.5
-75 -50 -25 0 25 50 75 100 125 150 175
T [°C]
Drop [V]
I
OUT
=700mA
, V
OUT
=2.7V, Duty cycle=100%
0
0.1
0.2
0.3
0.4
0.5
-75 -50 -25 0 25 50 75 100 125 150 175
T [°C]
Drop [V]
I
OUT
=700mA
, V
OUT
=2.7V, Duty cycle=100%
1.1
1.3
1.5
1.7
1.9
2.1
2.3
-75 -50 -25 0 25 50 75 100 125 150 175
T [°C]
PWM freq.[MHz]
V
IN
=V
EN
=3.6V, V
FB
=0.65V, V
OUT
=1.8V
1.1
1.3
1.5
1.7
1.9
2.1
2.3
-75 -50 -25 0 25 50 75 100 125 150 175
T [°C]
PWM freq.[MHz]
V
IN
=V
EN
=3.6V, V
FB
=0.65V, V
OUT
=1.8V
0
10
20
30
40
50
60
70
80
90
100
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8
I
OU
T
[A]
Efficiency [%]
V
IN
=V
EN
=3V, I
OUT
=from 10mA to 700mA, V
OUT
=1.2V
0
10
20
30
40
50
60
70
80
90
100
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8
I
OU
T
[A]
Efficiency [%]
V
IN
=V
EN
=3V, I
OUT
=from 10mA to 700mA, V
OUT
=1.2V
0
10
20
30
40
50
60
70
80
90
100
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7
I
OU
T
[A]
Efficiency [%]
V
IN
=V
EN
=3.6V, I
OUT
=from 10mA to 700mA, V
OUT
=1.8V
0
10
20
30
40
50
60
70
80
90
100
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7
I
OU
T
[A]
Efficiency [%]
V
IN
=V
EN
=3.6V, I
OUT
=from 10mA to 700mA, V
OUT
=1.8V
0
10
20
30
40
50
60
70
80
90
100
-75 -50 -25 0 25 50 75 100 125 150 175
T [°C]
Efficiency [%]
I
OUT
=100mA
I
OUT
=700mA
V
IN
=V
EN
=3.6V, V
OUT
=1.8V
0
10
20
30
40
50
60
70
80
90
100
-75 -50 -25 0 25 50 75 100 125 150 175
T [°C]
Efficiency [%]
I
OUT
=100mA
I
OUT
=700mA
V
IN
=V
EN
=3.6V, V
OUT
=1.8V
Typical performance characteristics ST1S12XX, ST1S12XX12, ST1S12XX18
12/20 Doc ID 14314 Rev 5
Figure 10. Efficiency vs. temperature Figure 11. Supply current vs. temperature
Figure 12. Quiescent current vs. temperature Figure 13. Enable voltage vs. temperature
Figure 14. Enable voltage vs. temperature Figure 15. Reference line regulation vs.
temperature
I
OUT
=100mA
I
OUT
=700mA
0
10
20
30
40
50
60
70
80
90
100
-75 -50 -25 0 25 50 75 100 125 150 175
T [°C]
Efficiency [%]
V
IN
=V
EN
=3V, V
OUT
=1.2V
I
OUT
=100mA
I
OUT
=700mA
0
10
20
30
40
50
60
70
80
90
100
-75 -50 -25 0 25 50 75 100 125 150 175
T [°C]
Efficiency [%]
V
IN
=V
EN
=3V, V
OUT
=1.2V
1
2
3
4
5
6
7
8
-75 -50 -25 0 25 50 75 100 125 150 175
T [°C]
I
SUPPLY
[mA]
V
IN
=V
EN
=3V, V
OUT
=1.2V, No Load
1
2
3
4
5
6
7
8
-75 -50 -25 0 25 50 75 100 125 150 175
T [°C]
I
SUPPLY
[mA]
V
IN
=V
EN
=3V, V
OUT
=1.2V, No Load
350
370
390
410
430
450
470
490
510
-75 -50 -25 0 25 50 75 100 125 150 175
T [°C]
I
SUPPLY
[µA]
V
IN
=V
EN
=3.6V, V
FB
=0.65V, C
IN
=C
OUT
=10µF, No Switching
350
370
390
410
430
450
470
490
510
-75 -50 -25 0 25 50 75 100 125 150 175
T [°C]
I
SUPPLY
[µA]
V
IN
=V
EN
=3.6V, V
FB
=0.65V, C
IN
=C
OUT
=10µF, No Switching
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
1.8
-75 -50 -25 0 25 50 75 100 125 150 175
T [°C]
V
EN
[V]
ON
OFF
V
IN
=2.5V, I
OUT
=10mA, C
IN
=C
OUT
=10µF, V
OUT
=1.8V
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
1.8
-75 -50 -25 0 25 50 75 100 125 150 175
T [°C]
V
EN
[V]
ON
OFF
V
IN
=2.5V, I
OUT
=10mA, C
IN
=C
OUT
=10µF, V
OUT
=1.8V
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
1.8
-75 -50 -25 0 25 50 75 100 125 150 175
T [°C]
V
EN
[V]
ON
OFF
V
IN
=5.5V, I
OUT
=10mA, C
IN
= C
OUT
=10µF, V
OUT
=1.8V
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
1.8
-75 -50 -25 0 25 50 75 100 125 150 175
T [°C]
V
EN
[V]
ON
OFF
V
IN
=5.5V, I
OUT
=10mA, C
IN
= C
OUT
=10µF, V
OUT
=1.8V
-0.6
-0.4
-0.2
-0
0.2
0.4
0.6
-75 -50 -25 0 25 50 75 100 125 150 175
T [°C]
LINE [%V
OUT
/ΔV
IN
]
V
IN
=V
EN
= 2.5V to 5.5V, C
IN
=C
OUT
=10µF, I
OUT
=10mA, V
OUT
=1.8V
-0.6
-0.4
-0.2
-0
0.2
0.4
0.6
-75 -50 -25 0 25 50 75 100 125 150 175
T [°C]
LINE [%V
OUT
/ΔV
IN
]
V
IN
=V
EN
= 2.5V to 5.5V, C
IN
=C
OUT
=10µF, I
OUT
=10mA, V
OUT
=1.8V
P1-P3P4-P6P7-P9P10-P12P13-P15P16-P18P19-P20

ST1S12GR

Mfr. #:
Buy ST1S12GR
Manufacturer:
STMicroelectronics
Description:
Switching Voltage Regulators SYNCH RECT W/ENABLE STEP-DOWN REG 1.7
Lifecycle:
New from this manufacturer.
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