t
ON
=
V
IN
1.3 x 10
-10
x
R1
User's Guide
SNVA147A – February 2006 – Revised April 2013
AN-1444 LM2695 Evaluation Board
1
Introduction
The LM2695EVAL 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 10 V output
over an input range of 12 V - 30 V. The circuit delivers load currents to 1A, with current limit set at
≊
1.3A.
The board is populated with all external components except R5, C8 and C11. These components provide
options for changing the current limit threshold, and managing the output ripple as described later in this
document.
The board’s specification are:
•
Input Voltage: 12 V to 30 V
•
Output Voltage: 10 V
•
Maximum load current: 1.0A
•
Minimum load current: 0A
•
Current Limit: 1.3A
•
Measured Efficiency: 96.3% (V
IN
= 12 V, I
OUT
= 300 mA)
•
Nominal Switching Frequency: 380 kHz
•
Size: 2.25 in. x 0.88 in. x 0.47 in
Figure 1. Evaluation Board - Top Side
2
Theory of Operation
Figure 6
shows a simplified block diagram of the LM2695. 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
SNVA147A – February 2006 – Revised April 2013
AN-1444 LM2695 Evaluation Board
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