SC4810B Ver la hoja de datos (PDF) - Semtech Corporation

Número de pieza

componentes Descripción

Fabricante

SC4810B

High Performance Current Mode PWM Controller with Complementary Output, Programmable Delay

Semtech Corporation 

SC4810B/E

POWER MANAGEMENT

Pin Descriptions (Cont.)

Pin # Pin # Pin Name

TSSOP MLPQ

Pin Function

9

7

SS

This pin serves two functions. The soft start timing capacitor connects to SS and is

charged by an internal 5µA current source. Under normal soft start SS is discharged

to less than 0.65V and then ramps positive to 1V during which time the OUT1 is held

low. As SS charges from 1V to 2.5V, soft start is implemented by an increasing

output duty cycle. If SS is taken below 0.5V, the output driver is inhibited and held low.

The user accessible 4V (A and D) or 5V (B, C and E) voltage reference also goes

low and IDD = 100µA.

10

8

CS

Current sense input is provided via the CS pin. The current sense input from a sense

resistor provides current feedback to the PWM comparator and current limit signal to

terminate the PWM pulse. When a pulse peak voltage provided at this pin exceeds

600mV, a soft-restart sequence will follow. Slope compensation is derived from the

rising voltage at the timing capacitor and can be buffered with an external small signal

PNP transistor.

11

9

FB

This pin is used to generate a reset signal when compared to CS for the PWM

comparator with an offset voltage of 600mV and 1/2 attenuation. The feedback

analog signal from the output of an error amplifier or an opto-coupler will be connected

to this pin to provide regulation.

12

10

GND Signal ground for all functions.

13

11

OUT2 This pin is the logic level drive output to the external MOSFET driver circuit (similar to

SC1302) for the complementary switch.

14

12

PGND Ground connection for the gate drivers. Connect PGND and GND at a single point.

15

13

OUT1 This pin is the logic level drive output to the external MOSFET driver circuit (similar to

SC1302) for the main switch.

16

14

VREF The 5V reference output. This reference is buffered and is available on the VREF pin.

VREF should be bypassed with a 0.47 - 1.0µF ceramic capacitor.

N/A

THERMAL Pad for heatsinking purposes only. Connect to ground plane using multiple vias. Not

PAD connected internally.

 2006 Semtech Corp.

7

www.semtech.com

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