ST1S15
500 mA, 6 MHz synchronous step-down converter
Datasheet - production data
Description
The ST1S15 is a high efficiency miniaturized
step-down converter able to provide 500 mA
output current from an input voltage from 2.3 V to
5.5 V. This converter is specifically designed for
applications where high efficiency and small
application area are the key factors. Thanks to
6 MHz switching frequency, the ST1S15 can use
470 nH nominal values for the inductor and
4.7 µF for the output capacitor providing, at the
same time, very good performance in terms of
load and line transients. A PFM mode can be
selected for high efficiency under light load
conditions or PWM mode for tight regulation and
best dynamic performance. Short-circuit and
thermal protection are also included.
Table 1: Device summary
Order code
ST1S15J18R
Output
voltage (V)
1.82
Package
Flip Chip 6
Features
85% typical efficiency
500 mA output current capability
45 µA typical quiescent current
PFM or PWM operation for best efficiency
over whole load range
Ultra-fast load and line transient
Short-circuit and thermal protection
Small external components
Auto or forced PWM selection with
dedicated pin
Available in Flip Chip 6 package
Applications
DSP and multimedia processor core supply
Cell phones
PDAs
February 2015
DocID023280 Rev 4
1/27
www.st.com
This is information on a product in full production.
Contents
ST1S15
Contents
1
2
3
4
5
6
7
Application schematic .................................................................... 5
Pin configuration ............................................................................. 6
Maximum ratings ............................................................................. 7
Electrical characteristics ................................................................ 8
Typical performance characteristics ........................................... 10
Block schematic ............................................................................ 13
Detailed description ...................................................................... 14
7.1
7.2
7.3
7.4
7.5
7.6
7.7
7.8
General description ......................................................................... 14
Mode transition................................................................................ 14
Soft-start ......................................................................................... 15
Short-circuit protection .................................................................... 15
Undervoltage lockout (UVLO) ......................................................... 15
Thermal protection .......................................................................... 16
Overcurrent protection .................................................................... 16
Enable function ............................................................................... 16
Input and output capacitors ............................................................. 17
Inductor ........................................................................................... 17
Layout guidelines ............................................................................ 18
8
Application information ................................................................ 17
8.1
8.2
8.3
9
Different output voltage versions of the ST1S15 available on
request .................................................................................................... 19
10
Package information ..................................................................... 20
10.1
10.2
Flip Chip 6 package information ...................................................... 21
Packing information ......................................................................... 24
11
Revision history ............................................................................ 26
2/27
DocID023280 Rev 4
ST1S15
List of tables
List of tables
Table 1: Device summary ........................................................................................................................... 1
Table 2: Typical external components ........................................................................................................ 5
Table 3: Pin description .............................................................................................................................. 6
Table 4: Absolute maximum ratings ........................................................................................................... 7
Table 5: Thermal data ................................................................................................................................. 7
Table 6: ESD performance ......................................................................................................................... 7
Table 7: Electrical characteristics ............................................................................................................... 8
Table 8: Inductors ..................................................................................................................................... 17
Table 9: Flip Chip 6 mechanical data ....................................................................................................... 22
Table 10: Tape and reel mechanical data ................................................................................................ 25
Table 11: Document revision history ........................................................................................................ 26
DocID023280 Rev 4
3/27
List of figures
ST1S15
List of figures
Figure 1: ST1S15 application schematic .................................................................................................... 5
Figure 2: Pin connections (top view) ........................................................................................................... 6
Figure 3: Efficiency vs. output current ...................................................................................................... 10
Figure 4: Output voltage vs. input voltage ................................................................................................ 10
Figure 5: Supply current vs. input voltage in auto mode .......................................................................... 10
Figure 6: Supply current vs. input voltage in PWM mode ......................................................................... 10
Figure 7: Output voltage vs. output current .............................................................................................. 10
Figure 8: Frequency vs. input voltage ....................................................................................................... 10
Figure 9: Output voltage vs. output current V
IN
=3.6 V .............................................................................. 11
Figure 10: Mode transition vs. input voltage ............................................................................................. 11
Figure 11: Mode transition PFM to PWM.................................................................................................. 11
Figure 12: Output voltage ripple (no-load) ................................................................................................ 11
Figure 13: Output voltage ripple ............................................................................................................... 11
Figure 14: Line transient ........................................................................................................................... 11
Figure 15: Load transient I
OUT
= 50 to 250 mA ......................................................................................... 12
Figure 16: Load transient I
OUT
= 250 to 50 mA ......................................................................................... 12
Figure 17: Enable startup ......................................................................................................................... 12
Figure 18: V
IN
startup ................................................................................................................................ 12
Figure 19: Block schematic ....................................................................................................................... 13
Figure 20: PFM to PWM transition ............................................................................................................ 14
Figure 21: PWM to PFM transition ............................................................................................................ 15
Figure 22: Flip Chip layout recommended (not in scale) .......................................................................... 18
Figure 23: Flip Chip 6 package outline ..................................................................................................... 21
Figure 24: Flip Chip 6 footprint recommended data (mm) ........................................................................ 23
Figure 25: Tape and reel outline ............................................................................................................... 24
4/27
DocID023280 Rev 4
ST1S15
Application schematic
1
Application schematic
Figure 1: ST1S15 application schematic
Table 2: Typical external components
Component
C
IN
C
OUT
L
Notes:
(1)
Manufacturer
Part number
GRM155R60J475ME87
GRM155R60G475ME87
Value
Size
Murata
(1)
4.7 µF
0402
GRM155R60J475ME87
LQM21PNR47MC0D
470 nH
2.0 x 1.25 x 0.5 mm
V
OUT
≤ 1.82 V
All the above components refer to a typical application. The ST1S15 operation is
not limited to the choice of these external components.
DocID023280 Rev 4
5/27
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