SC1403 Просмотр технического описания (PDF) - Semtech Corporation

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SC1403

Mobile Multi-Output PWM Controller with Lossless Current Sense

Semtech Corporation 

SC1403

POWER MANAGEMENT

Pin Descriptions

Pin # Pin Name Pin Function

1

CSH3 High-side current sense input for 3.3V SMPS. Connect to the high side of the DCR RC network, or

to the inductor side of a current sense resistor.

2

CSL3 Low side current sense input for 3.3V SMPS. For adjustable mode operation, connect to the 3.3V

output, at either the low side of the DCR RC network, or the output side of a current sense resistor.

For fixed-output operation, FB3 is grounded, and CSL3 also operates as the feedback sense input

for the 3.3V SMPS.

3

FB3 Feedback Input for the 3.3V SMPS. In adjustable mode (using external feedback resistors), FB3

regulates to REF (2.5V). When FB3 is grounded, internal resistors set a fixed 3.3V output.

4

COMP3 Compensation output of the 3.3V error amplifier.

5

COMP5 Compensation output of the 5.0V error amplifier.

6

SYNC Oscillator Synchronization and Frequency Select. Tie to VL for 300kHz operation; tie to GND for

200kHz. Drive externally to synchronize between 240kHz and 350kHz.

7

ON5 5V ON/OFF Control Input. Connect a 1K - 10K ohm resistor in series with ON5 to allow 5V

shutdown.

8

GND Low noise Analog Ground and Feedback reference point.

9

REF 2.5V Reference Voltage Output. Bypass to GND with 1 µF minimum.

10 PSAVE# Logic Control Input that disables PSAVE Mode when high. Connect to GND for normal use.

11 RESET# Active Low Timed Reset Output. RESET# swings GND to VL. Goes high after a fixed 32,000 clock

cycle delay following a successful power up.

12

FB5 Feedback Input for the 5V SMPS. In adjustable mode (using external feedback resistors), FB3

regulates to REF (2.5V). When FB5 is grounded, internal resistors set a fixed 5V output.

13

CSL5 Low side current sense input for 5V SMPS. For adjustable mode operation, connect to the 5V

output, at either the low side of the DCR RC network, or the output side of a current sense resistor.

For fixed-output operation, FB5 is grounded, and CSL5 also operates as the feedback sense input

for the 5V SMPS.

14

CSH5 High-side current sense input for 5V SMPS. Connect to the high side of the DCR RC network, or to

the inductor side of a current sense resistor.

15

SEQ Input that selects SMPS sequence for RESET#.

16

DH5 Gate Drive Output for the 5V, high side N-Channel switch.

17 PHASE5 5V SMPS Switching Node (inductor) connection.

18

BST5 Boost capacitor connection for 5V high side gate drive.

Note: All logic level inputs and outputs are open collector TTL compatible.

 2004 Semtech Corp.

7

United States Patent No. 6,377,032

www.semtech.com

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