AAT1236 Analogic Corporation, AAT1236 Datasheet - Page 10

• Manufacturer Part Number: AAT1236
• Manufacturer: Analogic Corporation

Functional Block Diagram
Functional Description
The AAT1236 consists of a controller for the step-up
switching converter and its power switch, and five
regulated current sinks programmable over 16 lev-
els into two groups, which can be turned on/off indi-
vidually. An external Schottky diode, a power induc-
tor, an output capacitor, and a resistor divider are
required to complete the solution.
The AAT1236's boost controller is designed to
deliver 100mA up to 24V. The AAT1236 is capable
of driving a total of five channels divided into two
groups with four white LEDs connected in series at
each channel.
The output load current can be programmed by the
current sink magnitudes. I
ming allows independent control of two groups of
10
SDA
SCL
VIN
OV
EN
IN
2
C interface program-
I
Converter
2
C Interface
Control
Boost
LIN
GND
V
V
V
V
(A1, A2, A3)
REF
(B1, B2)
REF
AGND
SW
High Efficiency White LED Drivers
current sinks (A1 to A3 and B1 to B2) and control
on/off with a different configuration on each chan-
nel. Unused sink channels should be connected to
AGND to prevent over voltage protection (OVP).
Control Loop
The AAT1236 provides the benefits of current
mode control with a simple hysteretic output cur-
rent loop providing exceptional stability and fast
response with minimal design effort. The device
maintains exceptional constant current regulation,
transient response, and cycle-by-cycle current limit
without additional compensation components.
The AAT1236 modulates the power MOSFET
switching current to maintain the programmed sink
current through each channel. The sink voltage at
each channel is monitored and the controller pro-
Max Current
Adjustment
ROM
ROM
for Backlight and Keypad
RSET
D/A
D/A
D/A
D/A
D/A
A1
A2
A3
B1
B2
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