herunterladen
t
ON
=
1.18 x 10
-10
x (R1
+ 1.4k)
(V
IN
- 1.4V)
+ 67 ns
J1
R4
L1
J3
GND
OUT1
OUT2
INGND
NATIONAL
SEMICONDUCTOR
LM5010A BUCK
EVALUATION
BOARD
C7
R
6
C9
C10 C8
D1
C
11
R3
R2
R1
C3
U1 C6
C2
C1
S/N
C5
C4
R5
/P N 55101 2686-001 REV A
C2005
User's Guide
SNVA137A–December 2005–Revised April 2013
AN-1423 LM5010A Evaluation Board
1 Introduction
The LM5010AEVAL 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 5V output
over an input range of 6V - 75V. The circuit delivers load currents to 1A, with current limit set at ≊1.3A.
The board is populated with all external components except R6 and C9-C11. These components provide
options for reducing output ripple as described later in this document.
The board’s specification are:
• Input Voltage: 6V to 75V
• Output Voltage: 5V
• Maximum load current: 1.0A
• Minimum load current: 0A
• Current Limit: 1.3A
• Measured Efficiency: 94.75% (V
IN
= 6V, I
OUT
= 200 mA)
• Nominal Switching Frequency: 200 kHz
• Size: 2.25 in. x 0.88 in. x 0.47 in
Figure 1. Evaluation Board - Top Side
2 Theory of Operation
The evaluation board schematic in Figure 3 contains a simplified block diagram of the LM5010A,
LM5010A-Q1 High-Voltage 1-A Step-Down Switching Regulator Data Sheet (SNVS376). When the circuit
is in regulation, the buck switch is on each cycle for a time determined by R1 and V
IN
according to
Equation 1:
(1)
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1
SNVA137A–December 2005–Revised April 2013 AN-1423 LM5010A Evaluation Board
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Verzeichnis
- ・ Blockdiagramm on Seite 4
- ・ Anwendungsbereich on Seite 7
