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dc2012af

DEMO MANUAL DC2012A

Description

LT8610AB

42V, 3.5A Micropower Synchronous

Step-Down Regulator

Demonstration circuit 2012A is a 42V, 3.5A micro-

power synchronous step-down regulator featuring the

LT®8610AB. The LT8610AB is a compact, high efficiency,

high speed synchronous monolithic step-down switching

regulator that consumes only 2.5µA of quiescent current

when output is regulated at 5V. The efficiency of the circuit

is greater than 90% at light load up to 1.5A. This is a 10%

improvementovercompetingparts.Topandbottompower

switches,compensationcomponentsandothernecessary

circuits are inside of the LT8610AB to minimize external

components and simplify design.

The SYNC pin on the demo board is grounded by default

for low ripple burst mode operation. To synchronous to an

external clock, move JP1 to SYNC and apply the external

clock to the SYNC turret. Once JP1 is on SYNC position,

to the SYNC turret for pulse-skipping operation. Figure 1

shows the efficiency of the circuit at 12V input.

L

, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks of Linear

Technology Corporation. All other trademarks are the property of their respective owners.

performance summary

Figure 2 shows the thermal performance of the circuit.

When running at input voltage greater than 30V, 3.5A

output current and 2MHz switching frequency, the tem-

perature rise will be significant. Either reducing the input

voltage, the output current or the switching frequency will

bring the temperature down to acceptable level without

external cooling.

The demo board has an EMI filter installed. The board

and the IC are designed to minimize conducted and radi-

ated EMI. The conducted EMI performance of the board

is shown on Figure 3. The limit in Figure 3 is EN55022

class B, average. It shows the circuit passes the test with

a wide margin.

The LT8610AB data sheet gives a complete description of

the part, operation and application information. The data

sheet must be read in conjunction with this quick start

guide for DC2012A.

Design files for this circuit board are available at

http://www.linear.com/demo/DC2012A

SYMBOL

PARAMETER

CONDITIONS

MIN

TYP

MAX

UNITS

Input Supply Range

5.5

42

V

Output Voltage

4.8

5

5.2

V

Maximum Output Current

3.5

A

Switching Frequency

1.85

2

2.15

MHz

EFE

Efficiency at DC

91

%

* Refer to Figure 2 to determine the maximum input voltage. If IC temperature exceeds target, reduce input voltage, output current or switching

frequency.