AS1860

Akros Silicon, Inc.

6399 San Ignacio Avenue, Suite 250, San Jose, CA 95119 USA

408.746.9000



http://www.AkrosSilicon.com

2

TABLE OF CONTENTS

GENERAL DESCRIPTION...........................................................................................................................................................1

TYPICAL APPLICATIONS ...........................................................................................................................................................1

SIMPLIFIED APPLICATION DIAGRAM .......................................................................................................................................1

FEATURES ..................................................................................................................................................................................1

POE PD CONTROLLER ..............................................................................................................................................................1

PRIMARY-SIDE DC-DC CONTROLLER......................................................................................................................................1

SECONDARY-SIDE POWER OUTPUTS.....................................................................................................................................1

POWER MANAGEMENT .............................................................................................................................................................1

EMC COMPLIANCE AND PROTECTION....................................................................................................................................1

FIGURES .....................................................................................................................................................................................4

TABLES........................................................................................................................................................................................5

PIN ASSIGNMENTS AND DESCRIPTIONS ................................................................................................................................6

TEST SPECIFICATIONS ...........................................................................................................................................................11

TYPICAL PERFORMANCE CHARACTERISTICS .....................................................................................................................18

FUNCTIONAL DESCRIPTION ...................................................................................................................................................19

ISOLATION ................................................................................................................................................................................19

PD CONTROLLER .....................................................................................................................................................................20

PD POWER MOSFET ................................................................................................................................................................20

UNDER-VOLTAGE LOCKOUT (UVLO) .....................................................................................................................................20

POE CURRENT LIMIT/CURRENT SENSE................................................................................................................................20

OVER-TEMPERATURE PROTECTION.....................................................................................................................................20

PD OPERATING STATES .........................................................................................................................................................20

AT DETECTION OPERATION ...................................................................................................................................................21

LOCAL POWER SOURCE .........................................................................................................................................................21

PWM CLOCK GENERATION.....................................................................................................................................................22

PWM CLOCK FREQUENCY CONFIGURATION .......................................................................................................................22

EXTERNAL CLOCK SOURCE (CLK_IN) ...................................................................................................................................22

EMI PERFORMANCE CONTROL..............................................................................................................................................22

POWER OUTPUT #1 .................................................................................................................................................................23

PRIMARY-SIDE DC-DC CONTROLLER....................................................................................................................................23

SOFT-START INRUSH CURRENT LIMIT..................................................................................................................................24

CURRENT-LIMIT AND CURRENT SENSE................................................................................................................................24

SECONDARY-SIDE SYNC CONTROLLER ...............................................................................................................................24

COMPENSATION AND LOOP FEEDBACK...............................................................................................................................24

LOW-LOAD CURRENT OPERATION - DCM.............................................................................................................................24

OVER-VOLTAGE PROTECTION...............................................................................................................................................24

POWER OUTPUTS #2 AND #3 .................................................................................................................................................24

LOOP FEEDBACK AND COMPENSATION...............................................................................................................................25

CURRENT-LIMIT AND CURRENT SENSE................................................................................................................................25

OVER-VOLTAGE PROTECTION...............................................................................................................................................25

POWER OUTPUT #4 .................................................................................................................................................................25

COMPENSATION AND LOOP FEEDBACK...............................................................................................................................26

CURRENT-LIMIT AND CURRENT SENSE................................................................................................................................27

OVER-VOLTAGE PROTECTION...............................................................................................................................................27

HARDWARE MODE OPERATION.............................................................................................................................................27

DEVICE INITIALIZATION & HARDWARE MODE SELECTION.................................................................................................27

HW MODE POWER OUTPUT CONTROLS...............................................................................................................................27

HW MODE POWER OUTPUT SEQUENCING...........................................................................................................................27

HW MODE POWER MONITORING (PGOOD) ..........................................................................................................................28

HW MODE WATCHDOG TIMER ...............................................................................................................................................28

WATCHDOG CONFIGURATION ...............................................................................................................................................28

WATCHDOG SERVICE .............................................................................................................................................................28

WATCHDOG TIMEOUT .............................................................................................................................................................28

HW MODE GENERAL-PURPOSE I/O OPERATION .................................................................................................................28

SOFTWARE MODE OPERATION .............................................................................................................................................28

DEVICE INITIALIZATION AND SOFTWARE MODE SELECTION ............................................................................................28

SW MODE POWER OUTPUT CONTROLS...............................................................................................................................29

SW MODE POWER OUTPUT SEQUENCING...........................................................................................................................29