AAT1235 Datasheet, PDF (2/21 Pages) Advanced Analogic Technologies – High Efficiency White LED Drivers for Backlight and Keypad

AAT1235
High Efficiency White LED Drivers
for Backlight and Keypad
Pin Descriptions
Pin #
1
2
3
4
5
6
7
8
9
10, 11
12
13
14
15
16
EP
Symbol
VIN
OV
EN/SET
B1
B2
RSET
IN
GND
SW
N/C
AGND
A3
A2
A1
LIN
Function
Input supply for the converter. Connect a 2.2µF or larger ceramic capacitor from VIN to
GND.
Boost output over voltage detect pin. Use resistor divider to set the circuit's external over-
voltage protection. See Applications Information for details.
AS²Cwire control or enable pin.
Backlight current sink 1. Connect the cathode of the last LED in the string to B1.
Backlight current sink 2. Connect the cathode of the last LED in the string to B2.
LED current set resistor. A 22.6kΩ resistor from RSET to AGND sets the maximum LED cur-
rent in A1-A3 and B1-B2 to 20mA.
Input bias supply for the internal circuitry. Connect IN to VIN directly at the AAT1235.
Ground for the boost converter. Connect GND to AGND at a single point as close to the
AAT1235 as practical.
Boost converter switching node. A 2.2µH inductor, connected between SW and LIN, sets the
boost converter's switching frequency.
Not connected.
Ground pin. Connect AGND to GND at a single point as close to the AAT1235 as practical.
Auxiliary current sink 3. Connect the cathode of the last LED in the string to A3.
Auxiliary current sink 2. Connect the cathode of the last LED in the string to A2.
Auxiliary current sink 1. Connect the cathode of the last LED in the string to A1.
Switched power input. Connect LIN to the external power inductor.
Exposed paddle (bottom) Connected internally to SW. Connect to SW or leave floating.
Pin Configuration
TDFN34-16
(Top View)
VIN ¹
OV ²
EN/SET ³
B1 ⁴
B2 ⁵
RSET ⁶
IN ⁷
GND ⁸
16 _LIN
15 _A1
14 _A2
13 _A3
12 _AGND
11 N/C
10 _N/C
9 _SW
2
1235.2007.02.1.1