MAX8650(2006) Ver la hoja de datos (PDF) - Maxim Integrated

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MAX8650
(Rev.:2006)

4.5V to 28V Input Current-Mode Step-Down Controller with Adjustable Frequency

Maxim Integrated 

4.5V to 28V Input Current-Mode Step-Down

Controller with Adjustable Frequency

Pin Description (continued)

PIN

NAME

FUNCTION

Output Voltage Sensing for Overvoltage Protection. Connect OVP to the center of a resistor-divider

17

OVP

from OUT to GND to set the FB independent output overvoltage trip point. Connect OVP to FB if this

independence is not desired. The OVP threshold is 115% of the nominal FB regulation voltage.

18

FB

Feedback Input. Connect FB to the center of a resistor voltage-divider between the output and GND

to set the output voltage. The FB threshold regulates at 0.7V or VREFIN.

19

COMP

Loop Compensation. Connect COMP to an external RC network to compensate the loop. COMP is

internally pulled to GND through 20Ω during shutdown.

20

SS

Soft-Start. Connect a 0.1µF to 1µF ceramic capacitor from SS to GND. This capacitor sets the soft-

start period during startup. SS is internally pulled to GND through 20Ω during shutdown.

21

REFIN

External Reference Input. Connect REFIN to AVL to use the internal 0.7V reference for the feedback

threshold.

Programmable Current-Limit Input for the Low-Side MOSFET (LX-PGND). Connect a resistor from ILIM2

22

ILIM2

to GND to set the valley current-limit threshold. ILIM2 sources 5µA through the resistor, and the voltage

at ILIM2 is attenuated 5:1 to set the final current limit. For example, a 50kΩ resistor results in 250mV at

ILIM2. This results in a current-limit threshold (VLX - VPGND) of 50mV. VILIM2 must not exceed 1V.

Programmable Slope-Compensation Input. The slope-compensation voltage rate is the voltage at

23

SCOMP SCOMP times 0.1 divided by the oscillator period (T). Connect SCOMP to AVL or GND to set to the

default of 250mV/T or 125mV/T, respectively.

Open-Drain Output that Is High Impedance when the Output Voltage Rises Above 92% of the

24

POK

Nominal Regulation Value. POK pulls low during shutdown and when the output drops below 88% of

the nominal regulation value.

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