LM2670

SNVS036J – APRIL 2000 – REVISED APRIL 2013

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This is the input to a two-stage high gain amplifier, which drives the PWM controller. It is necessary to connect

pin 6 to the actual output of the power supply to set the dc output voltage. For the fixed output devices (3.3V, 5V

and 12V outputs), a direct wire connection to the output is all that is required as internal gain setting resistors are

provided inside the LM2670. For the adjustable output version two external resistors are required to set the dc

output voltage. For stable operation of the power supply it is important to prevent coupling of any inductor flux to

the feedback input.

ON/OFF

This input provides an electrical ON/OFF control of the power supply. Connecting this pin to ground or to any

voltage less than 0.8V will completely turn OFF the regulator. The current drain from the input supply when OFF

is only 50

μA. Pin 7 has an internal pull-up current source of approximately 20μA and a protection clamp zener

diode of 7V to ground. When electrically driving the ON/OFF pin the high voltage level for the ON condition

should not exceed the 6V absolute maximum limit. When ON/OFF control is not required pin 7 should be left

open circuited.

DAP (VSON PACKAGE)

The Die Attach Pad (DAP) can and should be connected to PCB Ground plane/island. For CAD and assembly

guidelines

refer

to

Application

Note

AN-1187

SNOA401

at

www.ti.com/lsds/ti/analog/powermanagement/power_portal.page.

10

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