AAT3170_08 Datasheet, PDF (11/15 Pages) Advanced Analogic Technologies – High Current LED Flash Driver Charge Pump IC

ChargePump^TM
PRODUCT DATASHEET
AAT3170
High Current LED Flash Driver Charge Pump IC
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.
C1
C2
1μF
1μF
2.7V to 5.5V
EN/SET
C1+
VIN
C1- C2+ C2-
VOUT
CIN
4.7μF
AAT 3170
EN/SET
F1
CT
F2
GND
COUT
2.2μF
Flash
LED
AUX_EN
Figure 1: Flash Plus Auxiliary Lighting.
C1
C2
1μF
1μF
2.7V to 5.5V
EN/SET
C1+ C1- C2+ C2+
VIN
VOUT
CIN
4.7μF
AAT 3170
EN/SET
F1
CT
F2
GND
COUT
2.2μF
Flash
LED
STAT1
STAT2
Figure 2: Flash Plus Status Lighting.
3170.2007.11.1.2
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