LM2651-3.3EVAL National Semiconductor, LM2651-3.3EVAL Datasheet
LM2651-3.3EVAL
Manufacturer Part Number
LM2651-3.3EVAL
Description
EVALUATION BOARD FOR LM2651-3.3
Manufacturer
National Semiconductor
Specifications of LM2651-3.3EVAL
Main Purpose
DC/DC, Step Down
Outputs And Type
1, Non-Isolated
Voltage - Output
3.3V
Current - Output
1.5A
Voltage - Input
4 ~ 14V
Regulator Topology
Buck
Frequency - Switching
300kHz
Board Type
Fully Populated
Utilized Ic / Part
LM2651
Lead Free Status / RoHS Status
Lead free / RoHS Compliant
Power - Output
-
Other names
*LM2651-3.3EVAL
© 2008 National Semiconductor Corporation
LM2651_3.3V_EVAL
1.5A High Efficiency
Synchronous Switching
Regulator Evaluation Board
Introduction
The LM2651 switching regulator provides high efficiency
power conversion over a 100:1 load range (1.5A to 15mA).
This feature makes the LM2651 an ideal fit in battery powered
applications.
Synchronous rectification and 75 mΩ internal switches pro-
vide up to 97% efficiency. At light loads, the LM2651 enters
a low power hysteretic or sleep mode to keep the efficiency
high. In many applications, the efficiency still exceeds 80% at
15 mA load.
A shutdown pin is available to disable the LM2651 and reduce
the supply current to 7 µA. The IC contains patented current
sensing circuitry for current mode control. This feature elimi-
nates the external current sensing required by other current
mode DC to DC converters. The IC has a 300kHz fixed fre-
quency internal oscillator. The high oscillator frequency al-
lows the use of extremely small, low profile components.
The evaluation board can be obtained by ordering part num-
ber LM2651_3.3V_EVAL from your local National Semicon-
ductor
www.national.com.
sales
office,
or
FIGURE 1. LM2651_EVAL Schematic for Adjustable Voltage
National's
101228
website
at
National Semiconductor
Application Note 1143
Ifeanyi Nwachukwu
July 24, 2008
Evaluation Board Design
The evaluation board is designed to supply 3.3V at 15 mA up
to 1.5A. The input voltage range is 4V to 14V. Components
were selected based on the design procedure in the LM2651
datasheet. PCB layout is critical to reduce noise and ensure
specified performance for any power supply design. To min-
imize the parasitic inductance in the loop of input capacitors
and the internal MOSFETs, connect the capacitors to V
PGND pins with short and wide traces. This is important be-
cause the rapidly switching current, together with wiring in-
ductance can generate large voltage spikes that may cause
noise problems. The feedback trace from the output to the
feedback pin should be wide, short and kept away from the
flux field of the inductor. The artwork for the evaluation board
is shown at the end of this application note and the schematic
shown in Figure 1. The parts list is given in Table 1. The pic-
torial representations of top, bottom and silkscreen layers are
shown at the end of this application note.
When an undervoltage situation occurs, the output voltage
can be pulled below ground as the inductor current is reversed
through the synchronous FET. For applications which need
to be protected from a negative voltage, a clamping diode D2
is recommended. When used, D2 should be connected cath-
ode to V
mum of 2A is recommended.
OUT
and anode to ground. A diode rated for a mini-
10122802
www.national.com
IN
and
Related parts for LM2651-3.3EVAL
Image
Part Number
Description
Manufacturer
Datasheet
Request
R
Part Number:
Description:
EVALUATION BOARD FOR LM2651-3.3
Manufacturer:
National Semiconductor
Datasheet:
Part Number:
Description:
National Semiconductor [8-Bit D/A Converter]
Manufacturer:
National Semiconductor
Datasheet:
Part Number:
Description:
National Semiconductor [Media Coprocessor]
Manufacturer:
National Semiconductor
Datasheet:
Part Number:
Description:
Digitally Controlled Tone and Volume Circuit with Stereo Audio Power Amplifier, Microphone Preamp Stage and National 3D Sound
Manufacturer:
National Semiconductor
Datasheet:
Part Number:
Description:
Digitally Controlled Tone and Volume Circuit with Stereo Audio Power Amplifier, Microphone Preamp Stage and National 3D Sound
Manufacturer:
National Semiconductor
Datasheet:
Part Number:
Description:
AC97 Rev 2 Codec with Sample Rate Conversion and National 3D Sound
Manufacturer:
National Semiconductor
Part Number:
Description:
Manufacturer:
National Semiconductor
Datasheet:
Part Number:
Description:
Manufacturer:
National Semiconductor
Datasheet:
Part Number:
Description:
General Purpose, Low Voltage, Low Power, Rail-to-Rail Output Operational Amplifiers
Manufacturer:
National Semiconductor
Datasheet:
Part Number:
Description:
8-bit 20 MSPS flash A/D converter.
Manufacturer:
National Semiconductor
Datasheet:
Part Number:
Description:
Low Noise Quad Operational Amplifier
Manufacturer:
National Semiconductor
Datasheet:
Part Number:
Description:
Quad Differential Line Receivers
Manufacturer:
National Semiconductor
Datasheet:
Part Number:
Description:
Quad High Speed Trapezoidal? Bus Transceiver
Manufacturer:
National Semiconductor
Datasheet:
Part Number:
Description:
Dual Line Receiver
Manufacturer:
National Semiconductor
Datasheet:
LM2651-3.3EVAL Summary of contents
Page 1
... In many applications, the efficiency still exceeds 80 load. A shutdown pin is available to disable the LM2651 and reduce the supply current to 7 µA. The IC contains patented current sensing circuitry for current mode control. This feature elimi- nates the external current sensing required by other current mode converters ...
Page 2
... Res 30.0 kΩ ⅛W 5% 0805 Schottky Diode 1A SMA OPERATING CONDITIONS The input voltage to the LM2651-3.3 regulator must be within the range 14V DC for proper operation. The device will not function properly with voltages below 4V and damage may occur if any voltage greater than 16V is applied. ...
Page 3
Notes 3 www.national.com ...
Page 4
... 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 ...