LM3243

SW

FB

EN

VCON

PGND

SGND

BP

ACB

GPIO

GPIO

MODE

PDM Output

DAC

10 µF

10 µF

4.7 µF

1.5 µH

BGND

LM3243

SNVS782B – OCTOBER 2010 – REVISED FEBRUARY 2013

www.ti.com

APPLICATION INFORMATION

Setting the Output Voltage

DAC Control

An analog voltage to the VCON pin can dynamically program the output voltage from 0.4V (typ.) to 3.6V (typ.) in

both PFM and PWM modes of operation, without the need for external resistors. The output voltage is governed

by Table 2.

Table 2. Output Voltage Selection

VCON (V)

VCON = 0.16V to 1.44V

2.5 x VCON

Figure 21. Dynamic Adjustment of Output Voltage with DAC or PDM

PDM-Based VCON Signal

Figure 21 shows the application circuit that enables the LM3243 to dynamically adjust the output voltage using a

GPIO pin from the system controller. Figure 22 shows the waveforms when adjusted dynamically. The PDM

signal of the GPIO is filtered using a low-pass filter and fed to the VCON pin. As the bitstream of the PDM signal

changes, the voltage on the VCON pin changes. Thus, the GPIO pin can be used to dynamically adjust the

output voltage. The double low-pass filter reduces the ripple at VCON to avoid any excessive VCON-induced

ripple at the output voltage.

14

Submit Documentation Feedback

Copyright © 2010–2013, Texas Instruments Incorporated

Product Folder Links: LM3243