LP3905SD-A3EV National Semiconductor, LP3905SD-A3EV Datasheet

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LP3905SD-A3EV

Manufacturer Part Number
LP3905SD-A3EV
Description
BOARD EVALUATION LP3905SD-A3
Manufacturer
National Semiconductor
Datasheets

Specifications of LP3905SD-A3EV

Main Purpose
DC/DC, Step Down with LDO
Outputs And Type
4, Non-Isolated
Voltage - Output
1.5V, 1.85V, 2.8V, 3V
Current - Output
600mA, 600mA, 100mA, 100mA
Voltage - Input
3 ~ 5.5V
Regulator Topology
Buck
Frequency - Switching
2MHz
Board Type
Fully Populated
Utilized Ic / Part
LP3905
Lead Free Status / RoHS Status
Contains lead / RoHS non-compliant
Power - Output
-
© 2007 National Semiconductor Corporation
LP3905-A3 Application
Board Information
General Information
The evaluation board is a complete circuit allowing full
operation of the LP3905 within the recommended application
circuit. Each board is pre-assembled and tested in the factory.
The board contains the LP3905-A3 in a 14 lead LLP package
with all the associated passive components to enable all fea-
tures of the device to be tested.
LP3905 is optimized for low power handheld applications.
This device provides two 600mA DC/DC Buck regulators, and
Schematic Diagram
Operational Information
The circuit used in the evaulation board is shown above.
The LP3905-A3 evaluation board has the output voltages set as follows:
The board is fitted with 0.47µF capacitors on the outputs of the LDO’s and thus the load current for these LDO’s should not
exceed 100mA.
The device has 1MΩ internal resistors from EN1 and EN2 to GND.
O/P
Buck1
Buck2
LDO1
LDO2
202091
Evaluation Board Schematic
LP3905-A3 Output Voltages
Voltage (V)
1.5
1.85
3.0
2.8
National Semiconductor
Application Note 1527
Graham Roxburgh
November 5, 2007
two 100mA linear regulators as configured on the board. The
LP3905-A3 allows the two buck output voltages to be set by
the user. This option is a variation on the LP3905 device which
has 4 fixed output voltages. The LP3905 additionally features
two enable pins allowing control over the device outputs.
www.national.com
20209101

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LP3905SD-A3EV Summary of contents

Page 1

... The board is fitted with 0.47µF capacitors on the outputs of the LDO’s and thus the load current for these LDO’s should not exceed 100mA. The device has 1MΩ internal resistors from EN1 and EN2 to GND. © 2007 National Semiconductor Corporation National Semiconductor Application Note 1527 ...

Page 2

Output Voltage Pre-set For initial use the LP3905-A3 sample board has been pre-set to 1.5V and 1.85V. The outputs of these two regulators may be set via the selection of the external resistor network form- ing the output feedback between ...

Page 3

Connection Information Connect a supply voltage (3.0V to 5.5V) to either of the VIN pins on the evaluation board. LK4 hardwired on the board connects both the BUCK supply side to the LDO supply side. These supplies are both required ...

Page 4

Bill of Materials for LP3905-A3 LLP Evaluation Board Item Type U1 L1,L2 Inductor C1, C3 Capacitor C4, C5, C6 Capacitor C2 Capacitor C7 Capacitor C8 Capacitor R1 Resistor R2 Resistor R3 Resistor R4 Resistor * - or similar. www.national.com Value ...

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5 www.national.com ...

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... For more National Semiconductor product information and proven design tools, visit the following Web sites at: Products Amplifiers www.national.com/amplifiers Audio www.national.com/audio Clock Conditioners www.national.com/timing Data Converters www.national.com/adc Displays www.national.com/displays Ethernet www.national.com/ethernet Interface www.national.com/interface LVDS www.national.com/lvds Power Management www.national.com/power Switching Regulators www.national.com/switchers LDOs www ...

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