AAT2856_08 Datasheet, PDF(14/18 Page) Advanced Analogic Technologies – High Current Charge Pump with Dual LDO for Backlight Applications

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AAT2856_08 Datasheet, PDF (14/18 Pages) Advanced Analogic Technologies – High Current Charge Pump with Dual LDO for Backlight Applications

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PRODUCT DATASHEET

AAT2856

ChargePumpTM High Current Charge Pump with Dual LDO for Backlight Applications

Figure 3: Example PCB Layout.

Evaluation Board User Interface

The user interface for the AAT2856 evaluation board is

provided through 4 buttons and a number of connection

terminals. The board is operated by supplying external

power and pressing individual buttons or button combi-

nations. The table below indicates the function of each

button or button combination.

To power-on the board, connect a power supply or bat-

tery to the DC- and DC+ terminals. Make the boardâs

supply connection by positioning the J1 jumper to the

ON position. A red LED indicates that power is applied.

The Enables of both LDOs are connected with jumpers J3

and J4. These terminals must be connected to the exter-

nal source to turn on/off the LDOs.

When applying external enable signals, consideration

must be given to the voltage levels. The externally

applied voltages cannot exceed the supply voltage that

is applied to the IN pins of the device (DC+).

The LDO loads can be connected directly to the evalua-

tion board. For adequate performance, be sure to con-

nect the load between OUTA/OUTB and DC- as opposed

to some other GND in the system.

Button(s)

Pushed

SW1

SW2

SW3

Description

[Push/Release once] Increment the number

of EN/SET edges, but the backlight current

is decreased (dimmer). If held down, auto-

cycle through the settings.

[Push/Release once] Decrement the number

of EN/SET edges, but the backlight current

is increased (brighter). If held down, auto-

cycle through the settings.

[Push/Release once] Toggle between 20mA

and 30mA maximum current.

Table 9: AAT2856 Evaluation Board User Interface1.

Evaluation Board Layout

Figure 4: AAT2856 Evaluation Board

Layout Top Side.

Figure 5: AAT2856 Evaluation Board

Layout Bottom Side.

1. The enable for LDOA and LDOB are manually set externally.

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2856.2008.02.1.3

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