SC2440 Просмотр технического описания (PDF) - Semtech Corporation

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SC2440

2.5 MHz Dual Switching Regulator with Integrated 2A Switches

Semtech Corporation 

SC2440

POWER MANAGEMENT

Pin Configuration

TOP VIEW

BOOST1

1

16

SW1

2

15

IN

3

14

SYNC

4

13

ROSC

5

12

IN

6

11

SW2

7

10

BOOST2

8

9

FB1

COMP1

PGOOD1

SS1

SS2

PGOOD2

COMP2

FB2

(16 Pin TSSOP-EDP)

Underside metal must be soldered to ground.

Ordering Information

Part Number

Package(1)(2)

SC2440TETRT

TSSOP-16 EDP

SC2440EVB

Evaluation Board

Notes:

(1) Only available in tape and reel packaging. A reel contains

2500 devices.

(2) Lead free product. This product is fully WEEE and RoHS

compliant.

Pin Descriptions

Pin #

Pin Name

1, 8

BOOST1,

BOOST2

2, 7

SW1, SW2

3, 6

IN

4

SYNC

5

9, 16

10, 15

ROSC

FB1, FB2

COMP1,

COMP2

11, 14

PGOOD1,

PGOOD2

12, 13

SS1, SS2

Underside

Metal

GND

© 2005 Semtech Corp.

Pin Function

Supply pins to the power transistor drivers.Tie to external diode-capacitor charge pumps to

generate drive voltages higher than VIN in order to fully saturate the internal NPN power switches.

Emitters of the internal power NPN transistors. Connect to the inductors, the freewheeling diodes

and the boost capacitors.

Input power supply pins of the SC2440 and also the common collector of the internal power

NPNs. Pins 3 and 6 are internally tied together and must be locally bypassed.

Driving the SYNC pin with an external clock synchronizes both step-down converters. The

external clock frequency must be at least twice the individual regulator set (or free-running)

frequency. Tie this pin to ground if not used.

An external resistor between this pin and the ground sets the master oscillator free-running

frequency. The set frequency is twice that of the individual switching regulator.

The inverting inputs of the error amplifiers. Each FB pin is tied to a resistive divider between its

output and the ground for setting the channel output voltage.

These are the outputs of the internal error amplifiers. The voltages on these pins control the peak

switch currents. RC networks at these pins compensate the control loops. Pulling either pin below

0.7V stops the corresponding switching regulator.

Open collector outputs of the Power Good comparators. Tie to external pull-up resistors from the

input or the output of the converter. The PGOOD outputs become valid as soon as VIN rises

above 1 VBE during power-up. PGOOD is actively pulled low until the corresponding FB pin rises

to within 10% of the final regulation voltage.

A capacitor from either SS pin to the ground provides soft-start and overload hiccup functions

for that channel. Pulling either SS pin below 0.8V with an open drain or collector transistor shuts

off the corresponding regulator. To completely shut off the SC2440 to low-current state, pull both

SS pins to the ground. Soft-start is recommended for all applications.

The exposed pad at the bottom of the package is the electrical ground connection of the

SC2440. It also provides a thermal contact to the circuit board. It is to be soldered to the ground

plane of the board.

4

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