LTC3442 View Datasheet(PDF) - Linear Technology

Part Name

Description

MFG CO.

LTC3442

Micropower Synchronous Buck-Boost DC/DC Converter with Automatic Burst Mode Operation

Linear Technology 

Prev 11 12 13 14 15 16 17 18 19 20

LTC3442

OPERATION

VIN

SOFT-START

CLAMP

TO PWM

VCI

COMPARATORS

14µA

ERROR AMP

1.22V

FB

12

VC CP1

11

VOUT

R1

R2

CHIP

ENABLE

SHDN/SS

1

RSS

CSS

ENABLE SIGNAL

3442 F05

0.7V

Figure 5. Soft-Start Circuitry

APPLICATIONS INFORMATION

COMPONENT SELECTION

VIN

1 SHDN/SS

2 RT

3 SGND

4 SW1

5 PGND

6 SW2

FB 12

VC 11

RLIM 10

VIN 9

VOUT 8

BURST 7

VIN

VOUT

MULTIPLE

GND VIAS

RT

3442 F06

Figure 6. Recommended Component Placement. Traces Carrying

High Current Should Be Short and Wide. Trace Area at FB and VC

Pins Are Kept Low. Lead Length to Battery Should Be Kept Short.

VOUT and VIN Ceramic Capacitors Close to the IC Pins.

Inductor Selection

The high frequency operation of the LTC3442 allows the

use of small surface mount inductors. The inductor ripple

current is typically set to 20% to 40% of the maximum

inductor current. For a given ripple the inductance terms

are given as follows:

LBOOST

>

VIN(MIN) • (VOUT – VIN(MIN))H

f • ∆IL • VOUT

LBUCK

>

VOUT • (VIN(MAX) – VOUT )H

f • ∆IL • VIN(MAX)

where f = operating frequency, Hz

∆IL = maximum allowable inductor ripple current, A

VIN(MIN) = minimum input voltage, V

VIN(MAX) = maximum input voltage, V

VOUT = output voltage, V

IOUT(MAX) = maximum output load current

12

For more information www.linear.com/LTC3442

3442fb

Share Link: