AAT3170_08 datasheet(11/15 Pages) ANALOGICTECH

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AAT3170

High Current LED Flash Driver Charge Pump IC

ChargePumpTM

PRODUCT DATASHEET

3170.2007.11.1.2

www .analogictech.com

Applications Information

AS2Cwire Programming

Generally, programming the AAT3170 is achieved by

submitting bursts of address and data edges to the EN/

SET pin. However, in some cases multiple bursts of

address and data are needed to enable a particular oper-

ating mode. In other cases, only a single burst of data

edges is required.

To enable both flash channels to a current setting on the

LO scale, the user submits a single burst of address and

data edges. To enable both flash channels to a current

setting on the HI scale, the user must submit a burst of

address and data edges to program the current setting

level, and then submit a second burst of address and

data edges to program the HI/LO scale register to the HI

scale.

Shortcuts can also be used. If the device is in shutdown,

both flash channels can be enabled to a setting on the

LO scale by just giving a single burst of data edges. The

address edges are not needed because all registers are

reset during shutdown and address 0 is the default.

Further, a single burst of data edges can be used to

change from one setting to another for the last address.

The address register is not reset after each write; there-

fore, submitting address edges is only required when

changing the address.

Additional Applications

The constant voltage mode feature of the AAT3170

allows the user to combine the flash feature with addi-

tional applications. Additional applications such as auxil-

iary lighting and status LEDs can be added while elimi-

nating the need for an additional power supply, which is

normally required. Since the constant voltage mode can

supply a regulated output at up to 200mA load, it is

capable of driving ten LEDs at 20mA each. It is suitable

for keypad lighting, status lighting, and other applica-

tions where a 4.5V power supply could be used.

AAT3170

COUT

2.2μF

EN/SET

VIN

C1+

C1-

C2+

C2-

VOUT

2.7V to 5.5V

EN/SET

Flash

LED

GND

CIN

4.7μF

1μF

AUX_EN

Figure 1: Flash Plus Auxiliary Lighting.

AAT3170

COUT

2.2μF

EN/SET

VIN

C1+

C1-

C2+

VOUT

2.7V to 5.5V

EN/SET

Flash

LED

GND

CIN

4.7μF

1μF

STAT2

STAT1

Figure 2: Flash Plus Status Lighting.

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