Diodes AP3156 Manuel d'utilisateur télécharger pdf (Page 11)

AP3156

HIGH EFFICIENCY 1X/1.5X/2X CHARGE PUMP

FOR WHITE LED APPLICATIONS

AP3156 Rev. 1 11 of 15 SEPTEMBER 2009

www.diodes.com © Diodes Incorporated

SDI Command Timing Protocol

For the SDI command to be successfully received by the AP3156, all SDI timing specifications must be satisfied.

When no command is being sent, the SDI pin should be held High. If the SDI pin goes Low and stays Low for a time length between

SLO(min) and TSLO(max) and then goes High and stays High for the length between TSHI(min) and TSHI(max), one falling edge is

registered by the AP3156. The total number of falling edges registered before the SDI pin is held High for longer than the maximum

separation time T

SEP(max) identifies the command that has been received by the AP3156. The next series of falling edges before

another separation time of T

SEP represents the next command. In other words, the AP3156 counts the number of consecutive falling

edges on the SDI pin and a different number represents a different command.

Each command is executed after it is successfully received. If at any time the SDI pin is held Low for longer than the maximum chip

disable time T

OFF(max)

, then the AP3156 will be turned off and enters the shutdown mode. Setting the SDI pin switching from Low to High

will re-enable the AP3156 and leave the shutdown mode. If the SDI pin is held on for a time duration over T

SEP, then an end of a

sequence (EOS) occurs with a number of pulse conformed to specified timing.

A valid dual-sequence command occurs when one valid sequence is defined as an instruction, and the other is defined as data. Both

sequences have number of pulses less than 33. Also, a valid single-sequence command occurs when the sequence has number of

pulses greater than 32.

Channel 1 in

dimming control

SLO

SHI

SEP

SDI

Channel D2

910

Second Sequence

Channel D3

Channel D4

Channel D1

Channel Selection

Current Setting

Set Channel 1 to current level 2.

Channel D5

Channel D6

Channel 2 in

dimming control

Set Channel 2 to current level 2.

Channel 3 in

dimming control

Set Channel 3 to current level 2.

Channel 4 in

dimming control

Set Channel 4 to current level 2.

Channel 5 in

dimming control

Set Channel 5 to current level 2.

Channel 6 in

dimming control

Set Channel 6 to current level 2.

First Sequence

SEP

Figure 1: Dimming Control Selection (Dual-Sequence Command)

Serial Digital Interface

1 2 ... 6 7 8 9 10 11 12 13 14 15

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Diodes AP3156 Manuel d'utilisateur Page 11

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