EV2364DF-01A データシートの表示（PDF） - Monolithic Power Systems

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EV2364DF-01A

Dual 1.5A, 23V, 1.4MHz Step-Down Converter

Monolithic Power Systems 

TM

MP2364 — DUAL 1.5A, 23V, 1.4MHz STEP-DOWN CONVERTER

OPERATION

The MP2364 is a dual channel current mode

regulator. The COMP pin voltage is proportional

to the peak inductor current. At the beginning of

a cycle, the upper transistor M1 is off, and the

lower transistor M2 is on (see Figure 1). The

COMP pin voltage is higher than the current

sense amplifier output, and the current

comparator’s output is low. The rising edge of

the 1.4MHz CLK signal sets the RS Flip-Flop.

Its output turns off M2 and turns on M1 thus

connecting the SW pin and inductor to the input

supply. The increasing inductor current is

sensed and amplified by the Current Sense

Amplifier. Ramp compensation is summed to

Current Sense Amplifier output and compared

to the Error Amplifier output by the Current

Comparator.

When the sum of the Current Sense Amplifier

output and the Slope Compensation signal

exceeds the COMP pin voltage, the RS Flip-

Flop is reset. The MP2364 reverts to its initial

M1 off, M2 on state.

If the sum of the Current Sense Amplifier output

and the Slope Compensation signal does not

exceed the COMP voltage, the falling edge of

the CLK resets the Flip-Flop.

The output of the Error Amplifier integrates the

voltage difference between the feedback and

the 0.92V bandgap reference. The polarity is

such that a voltage at the FB pin lower than

0.92V increases the COMP pin voltage. Since

the COMP pin voltage is proportional to the

peak inductor current, an increase in its voltage

increases current delivered to the output. The

lower 10Ω switch ensures that the bootstrap

capacitor voltage is charged during light load

conditions. External Schottky Diode D1 carries

the inductor current when M1 is off (see Figure 1).

INA/

INB

ENA/

ENB

INTERNAL

REGULATORS

OSCILLATOR

SLOPE

COMP

210/1400KHz

CLK

+

0.7V --

--

SHUTDOWN

COMPARATOR

LOCKOUT

COMPARATOR

2.29V/

2.50V

+

+

--

CURRENT

SENSE

AMPLIFIER

+

--

+

SQ

RQ

--

CURRENT

COMPARATOR

1.8V

FREQUENCY

FOLDBACK

COMPARATOR

-- 0.4V

+

ERROR

AMPLIFIER

SGA/

SGB

FBA / FBB

Figure 1—Functional Block Diagram

(Diagram portrays ½ of the MP2364)

5V

BSA/

BSB

SWA/

SWB

COMPA/

COMPB

0.92V

SSA/

SSB

PGA/

PGB

MP2364_BD02

MP2364 Rev. 1.4

www.MonolithicPower.com

6

3/22/2006

MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited.

© 2006 MPS. All Rights Reserved.

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