National Instruments USB device 628x - Manual (Page 14)

NI USB-622x/625x/628x OEM User Guide 14 ni.com
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
power connector (reference designator J4/J6/J8
1 ) and must be 11–30 VDC,
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.
1 The power connector is designated as J4 on USB-6225/6255 OEM devices, J6 on USB-6221/6229 OEM devices, and J8 on
USB-6251/6259/6281/6289 OEM devices.
J4/J6/J8
VDC Out VDC In
XF1
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