The voltage regulation loop in the LM2674 regulates output voltage by maintaining the voltage on FB pin (VFB) to be the same as the internal REF voltage (VREF). A resistor divider pair is required to program the ratio from output voltage VOUT to VFB. The resistor is connected from the VOUT of the LM2674 to ground with the mid-point connecting to the FB pin. The voltage reference system produces a precise voltage reference over temperature. The internal REF voltage is 1.21 V typically. To program the output voltage of the LM2674 to be a certain value VOUT, R1 can be calculated with a selected R2 (see Adjustable Output Voltage Typical Application). R2 is in the range from 10 kΩ to 100 kΩ is recommended for most applications. If the resistor divider is not connected properly, output voltage cannot be regulated because the feedback loop is broken. If the FB pin is shorted to ground, the output voltage is driven close to VIN, because the regulator sees very low voltage on the FB pin and tries to regulator it up. The load connected to the output can be damaged under such a condition. Do not short FB pin to ground when the LM2674 is enabled. It is important to route the feedback trace away from the noisy area of the PCB. For more layout recommendations, see Layout.