AAT3141 datasheet(12/16 Pages) AAT

12 / 16 page

AAT3141

High Efficiency 1X/1.5X/2X Charge Pump

for White LED Applications

3141.2007.03.1.3

2Cwire Serial Interface

The current source output magnitude is controlled

by the AS

2Cwire serial digital input. AS2Cwire adds

addressing capability for multiple data registers

over the Simple Serial Control™ (S

2Cwire™),

which is only capable of controlling a single regis-

ter. The AAT3141 has two registers. One contains

the current level setting for outputs D1 to D3, and

the other contains the current level setting for out-

put D4.

Three addresses are used to control the two regis-

ters. Address 0 addresses both registers simulta-

neously to allow the loading of both registers with

the same data using a single write protocol.

Address 1 addresses Register 1 for D1 to D3 cur-

rent level settings. Address 2 addresses Register

2 for D4 current level settings.

As with S

2Cwire, AS2Cwire relies on the number of

rising edges of the EN/SET pin to address and load

the registers. AS

2Cwire latches data or address

after the EN/SET pin has been held high for time

LAT. Address or data is differentiated by the num-

ber of EN/SET rising edges. Since the data regis-

ters are 5 bits each, the differentiating number of

pulses is 2

5 or 32, so that Address 0 is signified by

33 rising edges, Address 1 by 34 rising edges and

Address 2 by 35 rising edges. Data is set to any

number of rising edges between 1 and including

32. A typical write protocol is a burst of EN/SET ris-

ing edges, signifying a particular address, followed

by a pause with EN/SET held high for the T

LAT time-

out period, a burst of rising edges signifying data,

and a T

LAT timeout for the data registers. Once an

address is set, then multiple writes to the corre-

sponding data register are allowed. Address 0 is

the default address on the first rising edge after the

AAT3141 has been disabled. If data is presented

on the first rising edge with no prior address, both

data registers are simultaneously loaded.

When EN/SET is held low for an amount of time

greater than T

OFF, the AAT3141 enters into shutdown

mode and draws less than 1µA from V

IN.

Data and

address registers are reset to 0 during shutdown.

Table 2: AS

2Cwire Serial Interface Addressing.

2Cwire Serial Interface Timing

Address

EN/SET Rising Edges

Data Register

1 & 2: D1-D4

D1-D3

Address

Data

EN/SET

Address

Data Reg 1

Data Reg 2

2 . . .

n <= 32

THI

TLO

TLAT

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