AAT3192_08 datasheet(10/18 Pages) ANALOGICTECH

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AAT3192

2-Channel Charge-Pump LED Driver

ChargePumpTM

PRODUCT DATASHEET

3192.2008.07.1.3

www .analogictech.com

S2Cwire Serial Interface

(AAT3192-1/-2/-3 only)

The LED output current of the AAT3192 is controlled by

AnalogicTech’s S2Cwire serial interface. Since the LED

current is programmable, no PWM or additional control

circuitry is needed to control LED brightness. This feature

greatly reduces the burden on a microcontroller or sys-

tem IC to manage LED or display brightness, allowing the

user to “set it and forget it.” With its high-speed serial

interface (1MHz data rate), the LED current can be

changed quickly and easily. Also the non-pulsating LED

current reduces system noise and improves LED reliabil-

ity. The S2Cwire interface relies on the number of rising

edges to the EN/SET pin to set the register. A typical

write protocol is a burst of EN/SET rising edges, followed

by a pause with EN/SET held high for at least tLAT (500μs).

The programmed current is then seen at the current sink

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

longer than tOFF (500μs), the AAT3192 enters into shut-

down mode and draws less than 1μA from the input and

the internal data register is reset to zero.

The AAT3192-1/2/3’s serial interface reduces the LED

current on each rising pulse of the enable input. If the

AAT3192 is in shutdown, the first rising edge of the EN/

SET input turns on the LED driver to the maximum cur-

rent. Successive rising edges decrease the LED current as

shown in Table 1 and Figure 2 for the AAT3192-1. For the

AAT3192-2, Table 2 and Figure 3 illustrate an 8-step LED

current control profile. For the AAT3192-3, Table 3 and

Figure 4 illustrate a 4-step LED current control profile.

EN/SET

n-1

n ≤ 16

Data Reg

n-1

THI

TLO

TLAT

TOFF

Figure 1: S2C Serial Interface Timing.

Data

EN Rising Edges

D1-D2 Current (mA)

18.7

17.3

14.7

13.3

10.7

9.3

6.7

5.3

2.7

1.3

0.63

Table 1: AAT3192-1 LED Current Settings.

S2Cwire Interface Data Code

0.00

5.00

10.00

15.00

20.00

3456

789

10 11 12 13 14 15 16

Figure 2: AAT3192-1 Current Control Profile.

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