ST ISA055V1 User Manual
STEVAL-ISA055V1
0.7 A / 1.2 V synchronous buck converter with enable function based on the ST1S12XX
Features
■Step-down current mode PWM (1.7 MHz) DCDC converter
■Fixed output voltage of 1.2 V
■0.7 A output current capability
■3% DC output voltage tolerance
■Synchronous rectification
■Enable function
■Internal soft-start
■Typical efficiency: > 90%
■Not switching quiescent current: max 600 µA over temperature range
■RDS(on) typ. 250 mΩand 400 mΩ
■Uses tiny capacitors and inductors
Data Brief
STEVAL-ISA055V1
Description
This demonstration board is based on the ST1S12 family of synchronous step-down DC-DC converters optimized for powering low-voltage digital cores in HDD (hard disk drive) applications and is generally used to replace high-current linear solutions when power dissipation may cause high heating of the application environment.
It provides up to 0.7 A over an input voltage range of 2.5 V to 5.5 V. A high switching frequency of 1.7 MHz allows the use of tiny surface-mount components. For the adjustable version, a resistor divider to set the output voltage value, an inductor, and two capacitors are required. Only an inductor and 2 capacitors are needed for the 1.2 V and 1.8 V fixed version. A low output ripple is guaranteed by the current mode PWM topology and by the use of low ESR surface-mount ceramic capacitors.
The ST1S12 device is thermal protected and current limited to prevent damage due to
accidental short-circuit. This family of products is available in the TSOT23-5L package.
September 2008 |
Rev 1 |
1/4 |
For further information contact your local STMicroelectronics sales office. |
www.st.com |
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Schematic diagram |
STEVAL-ISA055V1 |
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1 Schematic diagram
Figure 1. ST1S12 circuit schematic diagram
VIN |
VIN |
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REN |
ST1S12 |
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L |
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SW |
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1 |
EN |
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VOUT |
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VFB |
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GND |
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CIN |
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R1 |
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COUT |
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R2 |
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GND
AM00303
2/4
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