MAX5097 데이터 시트보기 (PDF) - Maxim Integrated

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MAX5097

40V, 600mA Buck Converters with Low Quiescent-Current Linear Regulator Mode

Maxim Integrated 

MAX5096/MAX5097

40V, 600mA Buck Converters with Low-

Quiescent-Current Linear Regulator Mode

5V TO 40V

VIN

CIN

100µF

CP

RC

CC

CSS

CCT

VIN

BP

EN

LDO/BUCK

LX

SYNC

COMP MAX5096

MAX5097

ADJ

OUT

SS

RESET

CT

GND PGND

1.0µF

22µH

D1*

+

B260/

COUT

MURS105 22µF

VOUT

R1

R2

RPU

RESET

*USE MURS105 IN APPLICATIONS

WHERE LDO MODE QUIESCENT

CURRENT IS CRITICAL.

Figure 4. Adjustable Output Voltage Configuration

Use typical values of VIN and fSW so that efficien-

cy is optimum for typical conditions. The switching

frequency (fSW) is fixed at 135kHz (MAX5096) and

330kHz (MAX5097). fSW can also be varied from 120kHz

to 500kHz (MAX5096) and from 300kHz to 500kHz

(MAX5097) when synchronized to an external clock (see

the Oscillator/Synchronization Input (SYNC) section). The

peak-to-peak inductor current, which reflects the peak-to-

peak output ripple, is worst at the maximum input voltage.

See the Output Capacitor Selection section to verify that

the worst-case output ripple is acceptable. The induc-

tor saturating current (ISAT) is also important to avoid

runaway current during continuous output short circuit.

Select an inductor with an ISAT specification higher than

the maximum peak current limit of 1.9A.

The buck mode operation determines the inductor and

output capacitor values. However, the values of the

inductor, its DCR, and the output capacitance/ESR affect

the closed-loop-transfer function both in buck and LDO

modes. The internal compensation of the MAX5096/

MAX5097 in LDO mode limits the values of these exter-

nal components. Make sure that the combination of

output inductor, capacitor, and ESR falls within the range

specified in Table 1.

Table 1. Inductor/Output Capacitor

Selection

INDUCTOR

22μH

47μH

100μH

OUTPUT CAPACITOR (COUT)

22μF, ESR = 5mΩ to 20mΩ (ceramic)

47μF, ESR = 40mΩ to 150mΩ

100μF, ESR = 30mΩ to 100mΩ

470μF/ESR = 60Ω to 400mΩ

22μF, ESR = 5mΩ to 20mΩ (ceramic)

47μF/ESR = 40mΩ to 150mΩ

100μF/ESR = 30mΩ to 100mΩ

470μF/ESR = 60mΩ to 400mΩ

22μF, ESR = 5mΩ to 20mΩ (ceramic)

47μF/ESR = 40mΩ to 150mΩ

100μF/ESR = 30mΩ to 100mΩ

470μF/ESR = 60mΩ to 400mΩ

Output Capacitor Selection

The allowable output-voltage ripple and the maximum

deviation of the output voltage during load steps deter-

mine the output capacitance and its ESR. The output

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