© National Instruments Corporation

13

NI USB-622x/625x/628x OEM User Guide

Power Switch

The power switch on the USB-622x/625x/628x OEM device powers the

device on and off. Figure 11 shows the pins on the power switch and

circuitry.

Figure 11. Schematic for the Power Switch

Pin 1, VDC In, is connected to VDC through the fuse (reference designator

XF1). The VDC is the voltage provided by the power supply through the

20 W.

Pin 2, VDC Out, provides power to the circuitry on the device. When the

switch is in the On position, the VDC power supply from pin 1 is routed to

pin 2.

Pin 3, 100 k

Ω to Ground, connects pin 2 to ground through a 100 kΩ

resistor when the switch is in the Off position.

USB-6251/6259/6281/6289 OEM devices.

J4/J6/J8

VDC Out

VDC In

Switch

1

2

3

NC

NC

100 k

Ω

SW1

Outer

Shell

SW1

XF1

FUSE

3

Power to

Device

J4/J6/J8

Power

Connector

1

2

100 k

Ω

100 k

Ω

to Ground