Data brief
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October 2011 Doc ID 022401 Rev 1 1/4
4
STEVAL-ISA044V6
3 A synchronous 900 kHz step-down DC-DC converter
with inhibit function based on the ST1S10 (DFN)
Features
■Input voltage range: 2.5 V to 18.0 V
■Max IOUT: 3 A
■High internal switching frequency: 900 kHz
■PWM mode operation with a fixed frequency or
synchronized to an external frequency
between 400 kHz and 1.2 MHz
■Inhibit pin available
■Quiescent current: < 6 µA in inhibit state
■RoHS compliant
Description
The STEVAL-ISA044V6 demonstration board is
based on the ST1S10 device assembled in a DFN
package. The ST1S10 is a step-down DC-DC
converter with the inhibit function optimized for
powering high voltages in LCD applications and
low voltages in digital-core HDD applications. It
replaces the high-current linear solution when
high power dissipation is an issue.
It provides up to 3 A over an input voltage range
of 2.5 V to 18.0 V, and synchronous rectification
removes the need for an external Schottky diode.
A high internal switching frequency (900 kHz)
allows for the use of tiny surface-mount
components, as well as a resistor divider to set
the output voltage value. Only an inductor and 3
capacitors are required.
The current-mode PWM architecture and stable
operation with low-ESR SMD ceramic capacitors
result in low output ripple. To maximize power
conversion efficiency in light load, the regulator
can work in burst mode automatically. The device
can operate in PWM mode with a fixed frequency
or synchronized to an external frequency. It
switches at a frequency of 900 kHz when the
SYNC pin is connected to ground or a fixed
voltage (less than 5.5 V), and can synchronize the
switching frequency between 400 kHz to 1.2 MHz
from an external clock applied to the SYNC pin.
A thermal shutdown circuit is integrated and
activates at 150 °C. Cycle-by-cycle current
limitation provides protection against shorted
outputs. The quiescent current is less than 6 µA in
the inhibit state.
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Schematic STEVAL-ISA044V6
2/4 Doc ID 022401 Rev 1
1 Schematic
Figure 1. Schematic
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STEVAL-ISA044V6 Revision history
Doc ID 022401 Rev 1 3/4
2 Revision history
Table 1. Document revision history
Date Revision Changes
25-Oct-2011 1 Initial release.
STEVAL-ISA044V6
4/4 Doc ID 022401 Rev 1
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