AAT3114AISN-20-T1 AAT [Advanced Analog Technology, Inc.], AAT3114AISN-20-T1 Datasheet - Page 8

• Manufacturer Part Number: AAT3114AISN-20-T1
• Description: High Efficiency 1.5X Fractional Charge Pumps For White LED Applications
• Manufacturer: AAT [Advanced Analog Technology, Inc.]

Functional Block Diagram
Functional Description
The AAT3113 and AAT3114/14A devices are high
efficiency 1.5X fractional charge pumps intended
for white LED backlight applications. The fraction-
al charge pump consists of a linear regulator fol-
lowed by a 1.5X charge pump. The AAT3113 and
AAT3114/14A require only four external compo-
nents: two 1µF ceramic capacitors for the charge
pump flying capacitors (C1 and C2),
ceramic capacitor for C
ceramic capacitor for C
put is converted into four or six constant current
outputs (D1 to D4 or D6) to drive four or six indi-
vidual LEDs with a maximum of 20mA each. The
current source output magnitude is controlled by
the EN/SET serial data S
interface records rising edges of the EN/SET pin
8
EN/SET
OUT
IN
, and one 0.33µF to 1µF
. The charge pump out-
2
Cwire interface.
Interface
S
2
Cwire
GND
one 1µF
5
The
Reference
Soft Start
Oscillator
600kHz
Voltage
32x8 bit
ROM
High Efficiency 1.5X Fractional Charge
Pumps For White LED Applications
and decodes them into 32 individual current level
settings each 1dB apart (see Table 1, Current
Level Settings). Code 32 is full scale, and Code 1
is full scale attenuated by 31dB. The modulo 32
interface wraps states back to state 1 after the
32nd clock. With each EN/SET pulse, the output
current increases by 1dB. To decrease the output
current by 1dB, 31 EN/SET clock pulses are
required. The counter can be clocked at speeds up
to 1MHz, so intermediate states are not visible.
The first rising edge of EN/SET enables the IC and
initially sets the output LED current to -31dB, the
lowest setting equal to 525µA. Once the final clock
cycle is input for the desired brightness level, the
EN/SET pin is held high to maintain the device out-
put current at the programmed level. The device is
disabled 500µs after the EN/SET pin transitions to
a logic low state.
8
Charge
Pump
1.5X
VIN
* AAT3114/14A only
Current
Mode
DAC
C2+
C1+
C2-
OUT
D1
D2
D3
D4
D5*
D6*
C1-
3113.2006.07.1.9