MAX1742 查看數據表（PDF） - Maxim Integrated

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MAX1742

1A/2.7A, 1MHz, Step-Down Regulators with Synchronous Rectification and Internal Switches

Maxim Integrated 

1A/2.7A, 1MHz, Step-Down Regulators with

Synchronous Rectification and Internal Switches

Typical Operating Characteristics (continued)

(Circuit of Figure 1, TA = +25°C, unless otherwise noted.)

MAX1842

LOAD-TRANSIENT RESPONSE

MAX1842 toc17

MAX1842

LINE-TRANSIENT RESPONSE

MAX1842 toc18

VINPUT

2V/div

VOUTPUT

50mV/div

0

IL

2A/div

VOUTPUT

20mV/div

AC-COUPLED

10μs/div

20μs/div

IOUT = 2.5A, VOUT = 1.5V, RTOFF = 100kΩ, L = 2.2μH

Pin Description

PIN

1

2, 4

3, 14, 16

5

6

7

8

9

10

11

12

13, 15

NAME

SHDN

IN

LX

SS

COMP

TOFF

FB

GND

REF

FBSEL

VCC

PGND

FUNCTION

Shutdown Control Input. Drive SHDN low to disable the reference, control circuitry, and internal

MOSFETs. Drive high or connect to VCC for normal operation.

Supply Voltage Input—for the internal PMOS power switch.

Connection for the drains of the PMOS power switch and NMOS synchronous-rectifier switch. Connect

the inductor from this node to the output filter capacitor and load.

Soft-Start. Connect a capacitor from SS to GND to limit inrush current during startup.

Integrator Compensation. Connect a capacitor from COMP to VCC for integrator compensation. See

Integrator Amplifier section.

Off-Time Select Input. Sets the PMOS power switch off-time during constant-off-time operation. Connect a

resistor from TOFF to GND to adjust the PMOS switch off-time.

Feedback Input—for both preset-output and adjustable-output operating modes. Connect directly to

output for fixed-voltage operation or to a resistive divider for adjustable operating modes.

Analog Ground

Reference Output. Bypass REF to GND with a 1µF capacitor.

Feedback Select Input. Selects output voltage. See Table 3 for programming instructions.

Analog Supply Voltage Input. Supplies internal analog circuitry. Bypass VCC with a 10Ω and 2.2µF low-

pass filter. See Figure 1.

Power Ground. Internally connected to the internal NMOS synchronous-rectifier switch.

8 _______________________________________________________________________________________

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