ST ST1S10 User Manual
3 A, 900 kHz, monolithic synchronous step-down regulator IC
Features
■ Step-down current mode PWM regulator
■ Output voltage adjustable from 0.8 V
■ Input voltage from 2.5 V up to 18 V
■ 2% DC output voltage tolerance
■ Synchronous rectification
■ Inhibit function
■ Synchronizable switching frequency from 400
kHz up to 1.2 MHz
■ Internal soft start
■ Dynamic short circuit protection
■ Typical efficiency: 90%
■ 3 A output current capability
■ Stand-by supply current: max 6 µA over
temperature range
■ Operative junction temp: from - 40 °C to 125 °C
Applications
■ Consumer
– STB, DV D, DV D r e c o r d e rs, TV, V C R , c a r
audio, LCD monitors
■ Networking
– XDSL, modems, DC-DC modules
■ Computer
– Optical storage, HD drivers, printers,
audio/graphic cards
■ Industrial and security
– Battery chargers, DC-DC converters, PLD,
PLA, FPGA, LED drivers
ST1S10
Datasheet − production data
DFN8 (4 x 4 mm)
Description
The ST1S10 is a high efficiency step-down PWM
current mode switching regulator capable of
providing up to 3 A of output current. The device
operates with an input supply range from 2.5 V to
18 V and provides an adjustable output voltage
from 0.8 V (V
V
*(1+R1/R2)]. It operates either at a 900 kHz
FB
fixed frequency or can be synchronized to an
external clock (from 400 kHz to 1.2 MHz). The
high switching frequency allows the use of tiny
SMD external components, while the integrated
synchronous rectifier eliminates the need for a
Schottky diode. The ST1S10 provides excellent
transient response, and is fully protected against
thermal overheating, switching over-current and
output short circuit.
The ST1S10 is the ideal choice for point-of-load
regulators or LDO pre-regulation.
) to 0.85*V
FB
IN_SW
PowerSO-8
[V
=
OUT
Table 1. Device summary
Order codes
Part number
DFN8 (4 x 4 mm) PowerSO-8
ST1S10 ST1S10PUR ST1S10PHR
June 2012 Doc ID 13844 Rev 5 1/29
This is information on a product in full production.
www.st.com
29
Contents ST1S10
Contents
1 Application circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
2 Pin configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
3 Maximum ratings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
4 Electrical characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
5 Application information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
5.1 Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
5.2 External components selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
5.2.1 Input capacitor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
5.3 Output capacitor (V
5.4 Output capacitor (0.8 V < V
> 2.5 V) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
OUT
< 2.5 V) . . . . . . . . . . . . . . . . . . . . . . . . . 12
OUT
5.5 Output voltage selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
5.6 Inductor (V
5.7 Inductor (0.8 V < V
> 2.5 V) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
OUT
< 2.5 V) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
OUT
5.8 Function operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
5.8.1 Sync operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
5.8.2 Inhibit function . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
5.8.3 OCP (overcurrent protection) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
5.8.4 SCP (short circuit protection) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
5.8.5 SCP and OCP operation with high capacitive load . . . . . . . . . . . . . . . . 14
6 Layout considerations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
6.1 Thermal considerations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
7 Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
8 Typical performance characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
9 Package mechanical data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
10 Revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
2/29 Doc ID 13844 Rev 5
ST1S10 List of tables
List of tables
Table 1. Device summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
Table 2. Pin description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Table 3. Absolute maximum ratings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Table 4. Thermal data. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Table 5. Electrical characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Table 6. Power SO-8 (exposed pad) mechanical data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
Table 7. Power SO-8 (exposed pad) tape and reel mechanical data . . . . . . . . . . . . . . . . . . . . . . . . 25
Table 8. DFN8 (4X4) mechanical data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
Table 9. DFN8 (4x4)tape and reel mechanical data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
Table 10. Document revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
Doc ID 13844 Rev 5 3/29
List of figures ST1S10
List of figures
Figure 1. Typical application circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Figure 2. Pin connections (top view for PowerSO-8, bottom view for DFN8) . . . . . . . . . . . . . . . . . . . 6
Figure 3. Application schematic for heavy capacitive load . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
Figure 4. Application schematic for low output voltage (V
Figure 5. Application schematic for low output voltage (V
Figure 6. PCB layout suggestion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
Figure 7. PCB layout suggestion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Figure 8. Block diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
Figure 9. Voltage feedback vs. temperature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
Figure 10. Oscillator frequency vs. temperature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
Figure 11. Max duty cycle vs. temperature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
Figure 12. Inhibit threshold vs. temperature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
Figure 13. Reference line regulation vs. temperature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
Figure 14. Reference load regulation vs. temperature. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
Figure 15. ON mode quiescent current vs. temperature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
Figure 16. Shutdown mode quiescent current vs. temperature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
Figure 17. PMOS ON resistance vs. temperature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
Figure 18. NMOS ON resistance vs. temperature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
Figure 19. Efficiency vs. temperature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
Figure 20. Efficiency vs. output current@V
Figure 21. Efficiency vs. output current@V
Figure 22. Efficiency vs. output current@V
= 5 V . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
out
= 3.3 V . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
out
= 12 V . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
out
Figure 23. Power SO-8 (exposed pad) dimensions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
Figure 24. Power SO-8 (exposed pad) recommended footprint . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
Figure 25. Power SO-8 (exposed pad) tape and reel dimensions . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
Figure 26. DFN8 (4x4) dimensions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
Figure 27. DFN8 (4x4)tape and reel dimensions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
< 2.5 V) and 2.5 V < VIN < 8 V . . . . . 15
OUT
< 2.5 V) and 8 V < V
OUT
< 16 V . . . . . . 15
IN
4/29 Doc ID 13844 Rev 5
ST1S10 Application circuit
1 Application circuit
Figure 1. Typical application circuit
L1
L1
3.3µH
3.3µH
12V
12V
C1
C1
4.7µF
4.7µF
C3
C3
0.1µF
0.1µF
VIN_SW
VIN_SW
EN
EN
VIN_A
VIN_A
ST1S10
ST1S10
SYNC
SYNC
AGND
AGND
PGND
PGND
SW
SW
FB
FB
R1
R1
R2
R2
C2
C2
22µF
22µF
5V – 3A
5V – 3A5V – 3A
Doc ID 13844 Rev 5 5/29
Pin configuration ST1S10
2 Pin configuration
Figure 2. Pin connections (top view for PowerSO-8, bottom view for DFN8)
DFN8 (4x4)
Table 2. Pin description
Pin n° Symbol Name and function
1V
IN_A
2 INH (EN) Inhibit pin active low. Connect to V
3V
FB
4 AGND Analog ground
5 SYNC
6V
IN_SW
7 SW Switching node to be connected to the inductor
8 PGND Power ground
epad epad Exposed pad to be connected to ground
Analog input supply voltage to be tied to VIN supply source
if not used
IN_A
Feedback voltage for connection to external voltage divider to set the V
from 0.8V up to 0.85*V
. (see output voltage selection paragraph 5.5)
IN_SW
Synchronization and frequency select. Connect SYNC to GND for 900 kHz
operation, or to an external clock from 400 kHz to 1.2 MHz. (see Sync
operation paragraph 5.8.1)
Power input supply voltage to be tied to VIN power supply source
PowerSO-8
OUT
6/29 Doc ID 13844 Rev 5
ST1S10 Maximum ratings
3 Maximum ratings
Table 3. Absolute maximum ratings
Symbol Parameter Value Unit
V
IN_SW
V
IN_A
V
V
V
I
INH
SW
FB
FB
Positive power supply voltage -0.3 to 20 V
Positive supply voltage -0.3 to 20 V
Inhibit voltage -0.3 to V
IN_A
V
Output switch voltage -0.3 to 20 V
Feedback voltage -0.3 to 2.5 V
FB current -1 to +1 mA
Sync Synchronization -0.3 to 6 V
T
T
STG
OP
Storage temperature range -40 to 150 °C
Operating junction temperature range -40 to 125 °C
Note: Absolute maximum ratings are the values beyond which damage to the device may occur.
Functional operation under these conditions is not implied.
Table 4. Thermal data
Symbol Parameter PowerSO-8 DFN8 Unit
R
thJA
R
thJC
Thermal resistance junction-ambient 40 40 °C/W
Thermal resistance junction-case 12 4 °C/W
Doc ID 13844 Rev 5 7/29
Electrical characteristics ST1S10
4 Electrical characteristics
V
= V
IN
+0.1 µF, C
the typical application circuit. Typical values assume T
Table 5. Electrical characteristics
Symbol Parameter Test conditions Min. Typ. Max. Unit
V
FB
I
FB
I
Q
I
OUT
Feedback voltage
VFB pin bias current 600 nA
Quiescent current
Output current
IN_SW
OUT
= V
IN_A
= V
= 12 V, V
INH
SYNC
= GND, V
OUT
= 5 V, I
= 10 mA, CIN = 4.7 µF
OUT
= 22 µF, L1 = 3.3 µH, TJ = -40 to 125°C (Unless otherwise specified, refer to
= 25°C).
J
T
= 25°C 784 800 816 mV
J
T
= -25°C to 125°C 776 800 824 mV
J
V
> 1.2 V, not switching 1.5 2.5 mA
INH
V
< 0.4 V 2 6 µA
INH
(1)
VIN = 2.5 V to 18 V V
0.8 V to 13.6 V
(2)
OUT
=
3.0 A
%V
OUT
%V
∆I
V
I
INH
INH
OUT
OUT
Inhibit threshold
Inhibit pin current 2 µA
/∆VINReference line regulation 2.5 V < V
/
Reference load regulation 10 mA < I
PWM fs PWM switching frequency
(2)
R
R
D
MAX
DSon
DSon
I
SWL
Maximum duty cycle
-N NMOS switch on resistance ISW = 750 mA 0.10 Ω
-P PMOS switch on resistance ISW = 750 mA 0.12 Ω
Switch current limitation 5.0 A
ν Efficiency
V
T
T
OUT
SHDN
HYS
/∆I
Thermal shut down 150 °C
Thermal shut down hysteresis 15 °C
Output transient response
OUT
Device ON 1.2 V
Device OFF 0.4 V
< 18 V 0.4
IN
< 3 A 0.5
OUT
= 0.7 V, Sync = GND TJ
V
FB
= 25°C
0.7 0.9 1.1 MHz
%V
∆V
%V
∆I
85 90 %
I
= 100 mA to 300 mA 85 %
OUT
= 300 mA to 3 A 90 %
I
OUT
100 mA < I
≥ 500 ns
< 1 A, tR = t
OUT
F
±5%V
OUT
IN
OUT
OUT
/
/
O
V
/∆I
OUT
@IO=short
F
SYNC
SYNC
V
IL_SYNC
Short circuit removal response
OUT
(overshot)
SYNC frequency capture range
SYNC pulse width V
WD
SYNC input threshold low V
10 mA < I
= 2.5 V to 18 V, V
V
IN
< short ±10 %V
OUT
0 to 5 V
= 2.5 V to 18 V 250 ns
IN
= 2.5 V to 18 V 0.4 V
IN
8/29 Doc ID 13844 Rev 5
SYNC
=
0.4 1.2 MHz
O
ST1S10 Electrical characteristics
Table 5. Electrical characteristics (continued)
Symbol Parameter Test conditions Min. Typ. Max. Unit
V
IH_SYNC
I
IL, IIH
SYNC input threshold high V
SYNC input current
UVLO Under voltage lock-out threshold
= 2.5 V to 18 V 1.6 V
IN
V
= 2.5 V to 18 V, V
IN
0 or 5 V
V
rising 2.3 V
IN
Hysteresis 200 mV
1. Guaranteed by design, but not tested in production.
2. See output voltage selection paragraph 5.5 for maximum duty cycle conditions.
SYNC
=
-10 +10 µA
Doc ID 13844 Rev 5 9/29
Loading...