ST EVAL5987, EVAL5987A User Manual
EVAL5987
EVAL5987A
3 A step-down switching regulator demonstration board based on the L5987, L5987A
Data brief
Features
■3 A DC output current
■2.9 V to 18 V input voltage
■Output voltage adjustable from 0.6 V to 16 V
■250 kHz switching frequency, programmable up to 1 MHz
■Internal soft-start and inhibit
■Low dropout operation: 100% duty cycle
■Zero-load current operation
■Overcurrent and thermal protection
■VFQFPN8 3 mm x 3 mm package or HSOP8
!-V
for the L5987A
Description
The EVAL5987/A demonstration board provides the design engineer with a fully functional stepdown switching regulator with an output current of up to 3 A. The board integrates STMicroelectronics’ L5987/A step-down switching regulator, together with all the external components required for a typical application.
The rated voltage of the input capacitor and the Schottky diode rectifier repetitive peak reverse voltage are both 25 V, making the board capable of covering the entire 2.9 V - 18 V input voltage range of the L5987/A device.
The board features an external resistor divider (R1 and R2) designed for an output voltage of 1.8 V.
The output voltage can be set to a level from 0.6 V up to the input voltage.
The compensation network on the demonstration board allows the use of MLCC as output filter to keep the loop stable. The inductor saturation current and forward current of the Schottky diode are within the current limit values.
The switching frequency on the demonstration board is set to 500 kHz by means of the R5 resistor connected to pin Fsw.
November 2009 |
Doc ID 16613 Rev 1 |
1/6 |
For further information contact your local STMicroelectronics sales office. |
www.st.com |
EVAL5987/A application circuit and component list |
EVAL5987 - EVAL5987A |
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1 EVAL5987/A application circuit and component list
Figure 1. Application circuit
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Figure 2. Package
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Table 1. |
Component list |
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Reference |
Part number |
Description |
Manufacturer |
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C1 |
GRM32ER61E226KE15 |
22 µF, 25 V |
Murata |
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C2 |
GRM32ER61E226KE15 |
22 µF, 25 V |
Murata |
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C3 |
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2.2 nF, 50 V |
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C4 |
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10 nF, 50 V |
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C5 |
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330 pF, 50 V |
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C6 |
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220 nF, 25 V |
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R1 |
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4.99 kΩ, 1%, 0.1 W 0603 |
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R2 |
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2.49 kΩ, 1%, 0.1 W 0603 |
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R3 |
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330 Ω, 1%, 0.1 W 0603 |
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R4 |
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2 kΩ, 1%, 0.1 W 0603 |
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R5 |
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100 kΩ, 1%, 0.1 W 0603 |
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L1 |
MSS1038-522NL |
5.2 µH, 30%, 5.28 A |
Coilcraft |
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D1 |
STPS2L25V |
2 A, 25 V |
STMicroelectronics |
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2/6 |
Doc ID 16613 Rev 1 |
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