herunterladen
t
ON
=
(V
IN
± 1.5V)
1.14 x 10
-10
x (R1 + 1.4k)
+ 95 ns
User's Guide
SNVA161A–May 2006–Revised May 2013
AN-1472 LM2694 Evaluation Board
1 Introduction
The LM2694EVAL 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 5 V output
over an input range of 8 V - 30 V. The circuit delivers load currents to 0.5A, with current limit set at
≊0.65A. The board is populated with all external components except R4, C6, C9 and C12. These
components provide options for managing the output ripple voltage as described later in this document.
The board’s specification are:
• Input Voltage: 8V to 30V
• Output Voltage: 5V
• Maximum load current: 0.5A
• Minimum load current: 0A
• Current Limit: 0.65A
• Measured Efficiency: 93.4% (V
IN
= 8V, I
OUT
= 200 mA)
• Nominal Switching Frequency: 250 kHz
• Size: 2.25 in. x 0.88 in. x 0.55 in
Figure 1. Evaluation Board - Top Side
2 Theory of Operation
Refer to the evaluation board schematic in Figure 5. 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
SNVA161A–May 2006–Revised May 2013 AN-1472 LM2694 Evaluation Board
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