u-boot/arch/arm/dts/am335x-boneblack.dts

/*
 * Copyright (C) 2012 Texas Instruments Incorporated - http://www.ti.com/
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 */
/dts-v1/;

#include "am33xx.dtsi"
#include "am335x-bone-common.dtsi"

&ldo3_reg {
	regulator-min-microvolt = <1800000>;
	regulator-max-microvolt = <1800000>;
	regulator-always-on;
};