V

R1 ) R2

R2

R1 + R2

V

OUT

V

DEFDCDCx

* R2

V

R5 ) R6

R6

R5 + R6

V

OUT

V

FBLDOx

* R6

TPS650241-Q1

TPS650243-Q1

Voltage Change on VDCDC3

The output voltage of VDCDC3 can be changed during operation from, for example, 0.9V to 1.375V

(TPS650241) and back. While the output voltage at VDCDC1 and VDCDC2 is fixed after the device exits

undervoltage lockout (UVLO), the status of the DEFDCDC3 pin is sensed during operation and the voltage is

changed as soon as the logic level on this pin changes from low to high or vice versa. Therefore it is not possible

to connect a resistor divider to DEFDCDC3 and set a voltage different from the predefined voltages.

Vdd_alive Output

The Vdd_alive LDO is typically connected to the Vdd_alive input of the Samsung application processor. It

provides an output voltage of 1.2V at 30mA. For the TPS650245, the output voltage is 1.1V. It is recommended

to add a capacitor of 2.2

μF minimum to the Vdd_alive pin. The LDO can be disabled by pulling the

EN_Vdd_alive pin to GND.

LDO1 and LDO2

The LDOs in the TPS65024x are general purpose LDOs which are stable using ceramics capacitors. The

minimum output capacitor required is 2.2

μF. The LDOs output voltage can be changed to different voltages

between 1.0V and Vin using an external resistor divider. Therefore they can also be used as general purpose

LDOs in the application. The supply voltage for the LDOs needs to be connected to the VINLDO pin, giving the

flexibility to connect the lowest voltage available in the system and therefore providing the highest efficiency.

The total resistance (R5+R6) of the voltage divider should be kept in the 1M

Ω range in order to maintain high

Vcc-Filter

An RC filter connected at the Vcc input is used to keep noise from the internal supply for the bandgap and other

analog circuitry. A typical value of 1

Ω and 1μF is used to filter the switching spikes, generated by the DC/DC

converters. A larger resistor than 10

Ω should not be used because the current into Vcc of up to 2.5mA causes a

voltage drop at the resistor causing the undervoltage lockout circuitry connected at Vcc internally to switch off too

early.

Copyright © 2009, Texas Instruments Incorporated

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Product Folder Link(s): TPS650241-Q1 TPS650243-Q1