LINEAR High Efficiency 2-Phase Boost Converter - Minimizes Input & Output Current Ripple – Design Note 371 Data Sheet User Manual

High Efficiency 2-Phase Boost Converter Minimizes Input and Output Current Ripple – Design Note 371 Goran Perica

Introduction also increase proportional to the output-to-input voltage conversion ratio, so if the input voltage is low, the

Many automotive and industrial applications require higher

switching currents can overwhelm a simple boost con-

voltages than is available on the input power supply rail.

verter and generate unacceptable EMI.

A simple DC/DC boost converter suffices when the power levels are in the 10W to 50W range, but if higher power

For example, consider Figure 1, a 12V input to 24V, 10A

levels are required, the limitations of a straightforward

output switching converter operating at 300k Hz. The

boost converter become quickly apparent. Boost con-

currents processed by the converter in Figure 1 are shown

verters convert a low input voltage to a higher output

in the first row of Table 1. The relatively high current levels

voltage by processing the input current with a boost

in the switcher are reflected in high input and output ripple

inductor, power switch, output diode and output capaci-

currents, which results in increased EMI.

tor. As the output power level increases, the currents in

, LTC, LT and Burst Mode are registered trademarks of Linear Technology

these components increase as well. Switching currents Corporation. All other trademarks are the property of their respective owners.

INPUT 10V TO 23V

MBRB2545

13.3k OUTPUT

RUN VIN 24V

12k4.7n F LTC1871-7

HAT2165 10A

ITH GATE

FREQ SENSE VOUT

100m V/DIV

MODE/SYNC INTVCC 0.002Ω

VFB GND

DN371 F01 DN371 F01b

1μs/DIV

229k L1: COOPER HC3-4R7 ALL CERAMIC CAPACITORS ARE X7R, TDK

Figure 1b. Single-Phase Boost Converter Output Voltage Ripple

Figure 1a. Single-Phase Boost Converter: Can be Used to Convert 12V Input to 24V, 10A Output

Table 1. Dual-Phase Boost Converter Has Lower Input and Output Ripple Currents and Voltages Than Single-Phase Boost Converter

MOSFET OUTPUT OUTPUT OUTPUT OUTPUT

INPUT RMS INPUT RIPPLE RMS DRAIN DIODE CAPACITOR CAPACITOR VOLTAGE CURRENT CURRENT CURRENT RMS CURRENT RMS CURRENT FREQUENCY RIPPLE

SINGLE-PHASE

BOOST 21.1A 4.2AP-P 15.4A 14.4A 10.5A 300k Hz 212m V

CONVERTER DUAL-PHASE BOOST 20.7A 0.17AP-P 2 × 7.4A 2 × 7.2A 1.9A 600k Hz 65m V CONVERTER