herunterladen
t
ON
=
V
IN
1.25 x 10
-10
x
R1
User's Guide
SNVA148D–February 2006–Revised April 2013
AN-1445 LM5009 Evaluation Board
1 Introduction
The LM5009EVAL evaluation board provides the design engineer with a fully functional buck regulator,
employing the constant on-time (COT) operating principle. This evaluation board provides a 10V output
over an input range of 12V - 95V. The circuit delivers load currents to 150 mA, with current limit at ≊240
mA. The board is populated with all external components except C6 and C9. These components provide
options for managing the output ripple as described later in this document.
The board’s specification are:
• Input Voltage: 12V to 95V
• Output Voltage: 10V
• Maximum load current: 150 mA
• Minimum load current: 0 mA
• Current Limit: ≊240 mA
• Measured Efficiency: 93.3% (V
IN
= 12V, I
OUT
= 100 mA)
• Nominal Switching Frequency: 240 kHz
• Size: 1.6 in. x 1.0 in. x 0.5 in
Figure 1. Evaluation Board - Top Side
2 Theory of Operation
Refer to the evaluation board schematic in Figure 5, which contains a simplified block diagram of the
LM5009. When the circuit is in regulation, the buck switch is on each cycle for a time determined by R1
and the input voltage according to the equation:
(1)
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1
SNVA148D–February 2006–Revised April 2013 AN-1445 LM5009 Evaluation Board
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Verzeichnis
- ・ Blockdiagramm on Seite 5
- ・ Anwendungsbereich on Seite 10
